1. lіver. gall bladder. pancreas
2. perіtoneum n(visceral and parietal sheets).
3. External nose. nasal cavity. larynx
Lesson No 13
Theme 1. lіver. gall bladder. npancreas
The liver, the largest gland in the body, also nperforms important exocrine and metabolic functions:
· nThe secretion of nbile.
· nThe protective nrole by detoxifying substances.
· nThe storehouse nfor various substances.
· nMetabolising the products nof digestion.
· nThe synthesis of nproteins.
· nThe metabolism nof carbohydrates and the regulation of blood glucose.
· nThe metabolism nof fats and the regulation of blood lipids.
· nThe conjugatioof substances.
· nThe ntransformation of substances.
· nThe productioof carbohydrates from proteins.
· nThe haemopoietic nfunction – especially during foetal life the liver is a centre for haemopoiesis nand new-born.
· nThe productioof thrombolitic agents.
· nThe synthesis of nprocoagulants.
Topography of the liver. Holotopy: Liver occupies nright hypochondriac region, proper epigastric region and small part of left nhypochondriac region. Skeletotopy: The upper edge of the liver projects iright 10th intercostal space (middle axillar line). Than it lifts to level of n4th rib (middle clavicular line) and passes across the sternum a bit upper from nxiphoid process, terminates in left 5th intercostal space (between middle nclavicular line and parasternal lines). The lower edge of the nliver passes along the costal arch from right 10th intercostal space (middle naxillar line). Than it crosses cartilage of right 9th rib and runs iepigastrium 1,5 cm nlower from xiphoid process to cartilage of left 8th rib and meets the upper nmargin.
Inferior surface of the liver
We distinguish the convex diaphragmatic surface of the liver and nlower visceral surface. Visceral surface adjoins to the organs, which nform on surface of the liver suitable ‘tracks’: renal, adrenal, gastric, nduodenal, oesophageal and colic impressions. Diaphragmatic surface ncarries cardiac impression.
Liver nis almost entirely covered with peritoneum except posteriorly positioned ‘area nnuda’. The superior surface is attached to the diaphragm and anterior abdominal nwall by a fold of peritoneum, the falciform ligament, in the free margiof which is a rounded cord, the ligamentum teres (obliterated umbilical nvein). The liver is connected to the lower surface of the diaphragm by the coronal nligament and the right and left triangular ligaments. The falciform nligament conventionally separates greater right lobe of liver and nlesser left lobe of liver.
The nporta hepatis, the entrance into the liver forms a ncross-connection between the sagittal grooves which together are shaped like aH. Visceral surface carries furrows: right nsagittal sulcus and left sagittal sulcus, which communicate by ntransversal sulcus (is called ‘porta hepatis’). Left sagittal nsulcus anteriorly contain fissure of teres ligament, where umbilical nvein in foetus passes. It obliterates in adult and forms teres liver nligament. Posterior portion of left sagittal sulcus is formed by fissura nof venous ligament (obliterated venous duct of Arantii). Right sagittal nsulcus anteriorly contains fossa of gall bladder, and behind – sulcus nof inferior vena cava. Vena portae, proper hepatic artery and nerves enter nthrough the porta hepatis into liver, common hepatic duct and lymphatic nvessels leave the parenchyma in this place. Sagittal and transversal sulcuses nlimit the quadrate lobe, positioned ventrally and caudate lobe, ndisposed dorsally. Caudate lobe carries papillary and caudate nprocesses.
The nliver is held together by a tense connective tissue capsule Glisson ‘s capsule. nAt the porta it separates the lobules of liver. The lobules form the nchief mass of the hepatic substance. Branches of portal vein, hepatic artery nand biliary duct form a hepatic triad are situated in stratums betweeliver lobules.
Unlike nall other organs a liver obtains arterial blood from proper hepatic artery nand venous – from portal vein. Entering into liver porta, a nportal vein and hepatic artery disintegrate into right and left lobar, nsegmental and lobular veins and arteries, which pass along interlobular nbile duct. Capillaries from these vessels joining together form sinusoid ncapillaries that receive mixed blood and empty into a central vein, nwhich occupies the centre of the lobule. Central vein drains into hepatic nveins, which leave the liver to end in the inferior vena cava. This nsystem is called as wonderful venous liver net.
Hepatic ncells ‘hepatocytes’ excrete the bile, which get into bile canaliculi. nLast pass to periphery emtpy into interlobular ductuli that form right nhepatic duct and left hepatic duct (from right and left hepatic nlobes). Common hepatic duct, which originated in porta, passes ihepatoduodenal ligament, meets the cystic duct and forms ductus ncholedochus. It flows together with pancreatic duct and forms commohepalopancreatic ampulla, which opens on major duodenal papilla. nThe ampulla may itself be closed by its own sphincter muscle, the sphincter ampullae n(Oddi).
The liver, the largest gland in the nbody, has both external and internal secretions, which are formed in the nhepatic cells. Its external secretion, the bile, is collected after npassing through the bile capillaries by the bile ducts, which join like the ntwigs and branches of a tree to form two large ducts that unite to form the nhepatic duct. The bile is either carried to the gall-bladder by the cystic duct nor poured directly into the duodenum by the common bile duct where it aids in digestion. nThe internal secretions are concerned with the metabolism of both nitrogenous nand carbohydrate materials absorbed from the intestine and carried to the liver nby the portal vein. The carbohydrates are stored in the hepatic cells in the nform of glycogen which is secreted in the form of sugar directly into the blood nstream. Some of the cells lining the blood capillaries of the liver are nconcerned in the destruction of red blood corpuscles. It is situated in the nupper and right parts of the abdominal cavity, occupying almost the whole of nthe right hypochondrium, the greater part of the epigastrium, and not nuncommonly extending into the left hypochondrium as far as the mammillary line. nIn the male it weighs from 1.4 to 1.6 kilogm., in the female from 1.2 to 1.4 nkilogm. It is relatively much larger in the fetus than in the adult, nconstituting, in the former, about one-eighteenth, and in the latter about one nthirty-sixth of the entire body weight. Its greatest transverse measurement is nfrom 20 to
To nobtain a correct idea of its shape it must be hardened in situ, and it nwill then be seen to present the appearance of a wedge, the base of which is ndirected to the right and the thin edge toward the left. Symington describes nits shape as that “of a right-angled triangular prism with the right angle nrounded off.”
Surfaces.—The nliver possesses three surfaces, viz., superior, inferior and posterior. nA sharp, well-defined margin divides the inferior from the superior in front; nthe other margins are rounded. The superior surface is attached to the diaphragm nand anterior abdominal wall by a triangular or falciform fold of peritoneum, nthe falciform ligament, in the free margin of which is a rounded cord, nthe ligamentum teres (obliterated umbilical vein). The line of nattachment of the falciform ligament divides the liver into two parts, termed nthe right and left lobes, the right being much the larger. The ninferior and posterior surfaces are divided into four lobes by five fossae, nwhich are arranged in the form of the letter H. The left limb of the H marks othese surfaces the division of the liver into right and left lobes; it is knowas the left sagittal fossa, and consists of two parts, viz., the fossa nfor the umbilical vein in front and the fossa for the ductus venosus nbehind. The right limb of the H is formed in front by the fossa for the ngall-bladder, and behind by the fossa for the inferior vena cava; nthese two fossae are separated from one another by a band of liver substance, ntermed the caudate process. The bar connecting the two limbs of the H is nthe porta (transverse fissure); in front of it is the quadrate nlobe, behind it the caudate lobe.
The nsuperior surface (facies superior) comprises a part of both nlobes, and, as a whole, is convex, and fits under the vault of the diaphragm nwhich in front separates it on the right from the sixth to the tenth ribs and ntheir cartilages, and on the left from the seventh and eighth costal ncartilages. Its middle part lies behind the xiphoid process, and, in the angle nbetween the diverging rib cartilage of opposite sides, is in contact with the nabdominal wall. Behind this the diaphragm separates the liver from the lower npart of the lungs and pleurae, the heart and pericardium and the right costal narches from the seventh to the eleventh inclusive. It is completely covered by nperitoneum except along the line of attachment of the falciform ligament.
The nsuperior surface of the liver
The ninferior surface (facies inferior; visceral surface)is uneven, nconcave, directed downward, backward, and to the left, and is in relation with nthe stomach and duodenum, the right colic flexure, and the right kidney and nsuprarenal gland. The surface is almost completely invested by peritoneum; the nonly parts devoid of this covering are where the gall-bladder is attached to nthe liver, and at the porta hepatis where the two layers of the lesser omentum nare separated from each other by the bloodvessels and ducts of the liver. The ninferior surface of the left lobe presents behind and to the left the gastric nimpression, moulded over the antero-superior surface of the stomach, and to nthe right of this a rounded eminence, the tuber omentale, which fits ninto the concavity of the lesser curvature of the stomach and lies in front of nthe anterior layer of the lesser omentum. The under surface of the right lobe nis divided into two unequal portions by the fossa for the gall-bladder; the nportion to the left, the smaller of the two, is the quadrate lobe, and nis in relation with the pyloric end of the stomach, the superior portion of the nduodenum, and the transverse colon. The portion of the under surface of the nright lobe to the right of the fossa for the gall-bladder presents two nimpressions, one situated behind the other, and separated by a ridge. The nanterior of these two impressions, the colic impression, is shallow and nis produced by the right colic flexure; the posterior, the renal impression, nis deeper and is occupied by the upper part of the right kidney and lower part nof the right suprarenal gland. Medial to the renal impression is a third and nslightly marked impression, lying between it and the neck of the gall-bladder. nThis is caused by the descending portion of the duodenum, and is known as the duodenal nimpression. Just in front of the inferior vena cava is a narrow strip of nliver tissue, the caudate process, which connects the right inferior nangle of the caudate lobe to the under surface of the right lobe. It forms the nupper boundary of the epiploic foramen of the peritoneum.
Posterior nand inferior surfaces of the liver.
The nposterior surface (facies posterior) is rounded and broad behind nthe right lobe, but narrow on the left. Over a large part of its extent it is nnot covered by peritoneum; this uncovered portion is about
The nanterior border (margo anterior) is thin and sharp, and marked nopposite the attachment of the falciform ligament by a deep notch, the umbilical nnotch, and opposite the cartilage of the ninth rib by a second notch for nthe fundus of the gall-bladder. In adult males this border generally ncorresponds with the lower margin of the thorax in the right mammillary line; nbut in women and children it usually projects below the ribs.
The nleft extremity of the liver is thin and flattened from above downward.
Fossae.—The left sagittal fossa (fossa sagittalis nsinistra; longitudinal fissure) is a deep groove, which extends from the nnotch on the anterior margin of the liver to the upper border of the posterior nsurface of the organ; it separates the right and left lobes. The porta joins nit, at right angles, and divides it into two parts. The anterior part, or fossa nfor the umbilical vein, lodges the umbilical vein in the fetus, and its nremains (the ligamentum teres) in the adult; it lies between the quadrate lobe nand the left lobe of the liver, and is often partially bridged over by a nprolongation of the hepatic substance, the pons hepatis. The posterior npart, or fossa for the ductus venosus, lies between the left lobe and the ncaudate lobe; it lodges in the fetus, the ductus venosus, and in the adult a nslender fibrous cord, the ligamentum venosum, the obliterated remains of nthat vessel.
The nporta or transverse fissure (porta hepatis) is a short but ndeep fissure, about
The nfossa for the gall-bladder (fossa vesicae felleae) is a shallow, noblong fossa, placed on the under surface of the right lobe, parallel with the nleft sagittal fossa. It extends from the anterior free margin of the liver, nwhich is notched by it, to the right extremity of the porta.
The nfossa for the inferior vena cava (fossa venae cavae) is a short ndeep depression, occasionally a complete canal in consequence of the substance nof the liver surrounding the vena cava. It extends obliquely upward on the nposterior surface between the caudate lobe and the bare area of the liver, and nis separated from the porta by the caudate process. On slitting open the ninferior vena cava the orifices of the hepatic veins will be seen opening into nthis vessel at its upper part, after perforating the floor of this fossa.
Lobes.—The nright lobe (lobus hepatis dexter) is much larger than the left; nthe proportion between them being as six to one. It occupies the right nhypochondrium, and is separated from the left lobe on its upper surface by the nfalciform ligament; on its under and posterior surfaces by the left sagittal nfossa; and in front by the umbilical notch. It is of a somewhat quadrilateral nform, its under and posterior surfaces being marked by nthree fossae: the porta and the fossae for the gall-bladder and inferior vena ncava, which separate its left part into two smaller lobes; the quadrate nand caudate lobes. The impressions on the right lobe have already beedescribed.
The nquadrate lobe (lobus quadratus) is situated on the under surface nof the right lobe, bounded in front by the anterior margin of the liver; behind nby the porta; on the right, by the fossa for the gall-bladder; and on the left, nby the fossa for the umbilical vein. It is oblong in shape, its nantero-posterior diameter being greater than its transverse.
The ncaudate lobe (lobus caudatus; Spigelian lobe) is situated upothe posterior surface of the right lobe of the liver, opposite the tenth and neleventh thoracic vertebrae. It is bounded, below, by the porta; on the right, nby the fossa for the inferior vena cava; and, on the left, by the fossa for the nductus venosus. It looks backward, being nearly vertical in position; it is nlonger from above downward than from side to side, and is somewhat concave ithe transverse direction. The caudate process is a small elevation of nthe hepatic substance extending obliquely lateralward, from the lower extremity nof the caudate lobe to the under surface of the right lobe. It is situated nbehind the porta, and separates the fossa for the gall-bladder from the ncommencement of the fossa for the inferior vena cava.
The nleft lobe (lobus hepatis sinister) is smaller and more flattened nthan the right. It is situated in the epigastric and left hypochondriac regions. nIts upper surface is slightly convex and is moulded on to the diaphragm; its nunder surface presents the gastric impression and omental tuberosity, already nreferred to page 1189.
Ligaments.—The nliver is connected to the under surface of the diaphragm and to the anterior nwall of the abdomen by five ligaments; four of these—the falciform, the coronary, nand the two lateral—are peritoneal folds; the fifth, the round nligament, is a fibrous cord, the obliterated umbilical vein. The liver is also nattached to the lesser curvature of the stomach by the hepatogastric and to the nduodenum by the hepatoduodenal ligament.
The nfalciform ligament (ligamentum falciforme hepatis) is a broad and nthin antero-posterior peritoneal fold, falciform in shape, its base being ndirected downward and backward, its apex upward and backward. It is situated ian antero-posterior plane, but lies obliquely so that one surface faces forward nand is in contact with the peritoneum behind the right Rectus and the ndiaphragm, while the other is directed backward and is in contact with the left nlobe of the liver. It is attached by its left margin to the under surface of nthe diaphragm, and the posterior surface of the sheath of the right Rectus as nlow down as the umbilicus; by its right margin it extends from the notch on the nanterior margin of the liver, as far back as the posterior surface. It is ncomposed of two layers of peritoneum closely united together. Its base or free nedge contains between its layers the round ligament and the parumbilical veins.
The ncoronary ligament (ligamentum coronarium hepatis) consists of aupper and a lower layer. The upper layer is formed by the reflection of nthe peritoneum from the upper margin of the bare area of the liver to the under nsurface of the diaphragm, and is continuous with the right layer of the nfalciform ligament. The lower layer is reflected from the lower margiof the bare area on to the right kidney and suprarenal gland, and is termed the nhepatorenal ligament.
The ntriangular ligaments (lateral ligaments) are two iumber, right nand left. The right triangular ligament (ligamentum triangulare ndextrum) is situated at the right extremity of the bare area, and is a nsmall fold which passes to the diaphragm, being formed by the apposition of the nupper and lower layers of the coronary ligament. The left triangular nligament (ligamentum triangulare sinistrum) is a fold of some nconsiderable size, which connects the posterior part of the upper surface of nthe left lobe to the diaphragm; its anterior layer is continuous with the left nlayer of the falciform ligament.
The nround ligament (ligamentum teres hepatis) is a fibrous cord nresulting from the obliteration of the umbilical vein. It ascends from the numbilicus, in the free margin of the falciform ligament, to the umbilical notch nof the liver, from which it may be traced in its proper fossa on the inferior nsurface of the liver to the porta, where it becomes continuous with the ligamentum nvenosum.
Fixatioof the Liver.—Several factors contribute to maintain the liver nin place. The attachments of the liver to the diaphragm by the coronary and ntriangular ligaments and the intervening connective tissue of the uncovered narea, together with the intimate connection of the inferior vena cava by the nconnective tissue and hepatic veins would hold up the posterior part of the nliver. Some support is derived from the pressure of the abdominal viscera which ncompletely fill the abdomen whose muscular walls are always in a state of tonic ncontraction. The superior surface of the liver is perfectly fitted to the under nsurface of the diaphragm so that atmospheric pressure alone would be enough to nhold it against the diaphragm. The latter in turn is held up by the negative npressure in the thorax. The lax falciform ligament certainly gives no support nthough it probably limits lateral displacement.
Liver nwith the septum transversum. Human embryo
Vessels nand Nerves.—The vessels connected nwith the liver are: the hepatic artery, the portal vein, and the hepatic nveins.
The nhepatic artery and portal vein, accompanied by numerous nerves, nascend to the porta, between the layers of the lesser omentum. The bile duct nand the lymphatic vessels descend from the porta between the layers of the same nomentum. The relative positions of the three structures are as follows: the nbile duct lies to the right, the hepatic artery to the left, and the portal nvein behind and between the other two. They are enveloped in a loose areolar ntissue, the fibrous capsule of Glisson, which accompanies the vessels itheir course through the portal canals in the interior of the organ.
The nhepatic veins convey the blood from the liver, and are described on page n680. They have very little cellular investment, and what there is binds their nparietes closely to the walls of the canals through which they run; so that, osection of the organ, they remain widely open and are solitary, and may be neasily distinguished from the branches of the portal vein, which are more or nless collapsed, and always accompanied by an artery and duct.
The nlymphatic vessels of the liver are described on page 711.
The nnerves of the liver, derived from the left vagus and sympathetic, enter nat the porta and accompany the vessels and ducts to the interlobular spaces. nHere, according to Korolkow, the medullated fibers are distributed almost nexclusively to the coats of the bloodvessels; while the non-medullated enter nthe lobules and ramify between the cells and even within them.
Structure nof the Liver.—The substance of the liver is composed of nlobules, held together by an extremely fine areolar tissue, in which ramify the nportal vein, hepatic ducts, hepatic artery, hepatic veins, lymphatics, and nnerves; the whole being invested by a serous and a fibrous coat.
The nserous coat (tunica serosa) is derived from the peritoneum, and ninvests the greater part of the surface of the organ. It is intimately adherent nto the fibrous coat.
The nfibrous coat (capsula fibrosa [Glissoni]; areolar coat) nlies beneath the serous investment, and covers the entire surface of the organ. nIt is difficult of demonstration, excepting where the serous coat is deficient. nAt the porta it is continuous with the fibrous capsule of Glisson, and on the nsurface of the organ with the areolar tissue separating the lobules.
The nlobules (lobuli hepatis) form the chief mass of the hepatic nsubstance; they may be seen either on the surface of the organ, or by making a nsection through the gland, as small granular bodies, about the size of a nmillet-seed, measuring from 1 to
A nsingle lobule of the liver
If none of the sublobular veins be laid open, the bases of the lobules may be seethrough the thin wall of the vein on which they rest, arranged in a form resembling na tesselated pavement, the center of each polygonal space presenting a minute naperture, the mouth of an intralobular vein .
Microscopic nAppearance—Each lobule consists of a mass of cells, hepatic cells, narranged in irregular radiating columns between which are the blood channels (sinusoids). nThese convey the blood from the circumference to the center of the lobule, and nend in the intralobular vein, which runs through its center, to open at nits base into one of the sublobular veins. Between the cells are also nthe minute bile capillaries. Therefore, in the lobule there are all the nessentials of a secreting gland; that is to say: (1) cells, by which the nsecretion is formed; (2) bloodvessels, in close relation with the cells, ncontaining the blood from which the secretion is derived; (3) ducts, by nwhich the secretion, when formed, is carried away.
The nhepatic artery, entering the liver at the porta with the portal vein and nhepatic duct, ramifies with these vessels through the portal canals. It gives noff vaginal branches, which ramify in the fibrous capsule of Glisson, nand appear to be destined chiefly for the nutrition of the coats of the vessels nand ducts. It also gives off capsular branches, which reach the surface nof the organ, ending in its fibrous coat in stellate plexuses. Finally, it ngives off interlobular branches, which form a plexus outside each nlobule, to supply the walls of the interlobular veins and the accompanying bile nducts. From this plexus lobular branches enter the lobule and end in the nnet-work of sinusoids between the cells.
The nportal vein also enters at the porta, and runs through the portal ncanals, enclosed in Glisson’s capsule, dividing in its course into branches, nwhich finally break up into a plexus, the interlobular plexus, in the ninterlobular spaces. These branches receive the vaginal and capsular veins, ncorresponding to the vaginal and capsular branches of the hepatic artery. Thus nit will be seen that all the blood carried to the liver by the portal vein and nhepatic artery finds its way into the interlobular plexus. From this plexus the nblood is carried into the lobule by fine branches which converge from the ncircumference to the center of the lobule, and are connected by transverse nbranches. The walls of these small vessels are incomplete so that the blood is nbrought into direct relationship with the liver cells. The lining endothelium nconsists of irregularly branched, disconnected cells (stellate cells of nKupffer). Moreover, according to Herring and Simpson, minute channels npenetrate the liver cells themselves, conveying the constituents of the blood ninto their substance. It will be seen that the blood capillaries of the liver nlobule differ structurally from capillaries elsewhere. Developmentally they are nformed by the growth of the columns of liver cells into large blood spaces or nsinuses, and hence they have received the name of “sinusoids.” Arrived at the ncenter of the lobule, the sinusoids empty themselves into one vein, of nconsiderable size, which runs down the center of the lobule from apex to base, nand is called the intralobular vein. At the base of the lobule this veiopens directly into the sublobular vein, with which the lobule is nconnected. The sublobular veins unite to form larger and larger trunks, and end nat last in the hepatic veins, these converge to form three large trunks which nopen into the inferior vena cava while that vessel is situated in its fossa othe posterior surface of the liver.
3. nThe bile ducts commence by little passages in the liver cells which ncommunicate with canaliculi termed intercellular biliary passages (bile ncapillaries). These passages are merely little channels or spaces left nbetween the contiguous surfaces of two cells, or in the angle where three or more nliver cells meet, and they are always separated from the blood capillaries by nat least half the width of a liver cell. The channels thus formed radiate to nthe circumference of the lobule, and open into the ninterlobular bile ducts which run in Glisson’s capsule, accompanying the portal nvein and hepatic artery. These joiwith other ducts to form two main trunks, which leave the liver at the ntransverse fissure, and by their union form the hepatic duct.
Structure nof the Ducts.—The walls of the biliary ducts consist of a connective-tissue ncoat, in which are muscle cells, arranged both circularly and longitudinally, nand an epithelial layer, consisting of short columnar cells resting on a ndistinct basement membrane.
Excretory nApparatus of the Liver.—The excretory apparatus of the liver nconsists of (1) the hepatic duct, formed by the junction of the two maiducts, which pass out of the liver at the porta; (2) the gall-bladder, nwhich serves as a reservoir for the bile; (3) the cystic duct, or the nduct of the gall-bladder; and (4) the common bile duct, formed by the njunction of the hepatic and cystic ducts.
The nHepatic Duct (ductus hepaticus).—Two maitrunks of nearly equal size issue from the liver at the porta, one from the nright, the other from the left lobe; these unite to form the hepatic duct, nwhich passes downward and to the right for about
The nGall-bladder (vesica fellea) is a conical or pear-shaped nmusculomembranous sac, lodged in a fossa on the under surface of the right lobe nof the liver, and extending from near the right extremity of the porta to the nanterior border of the organ. It is from 7 to
The ngall-bladder and bile ducts laid open.
Relations.—The nbody is in relation, by its upper surface, with the liver; by its under nsurface, with the commencement of the transverse colon; and farther back usually nwith the upper end of the descending portion of the duodenum, but sometimes nwith the superior portion of the duodenum or pyloric end of the stomach. The fundus nis completely invested by peritoneum; it is in relation, in front, with the nabdominal parietes, immediately below the ninth costal cartilage; behind with nthe transverse colon. The neck is narrow, and curves upon itself like nthe letter S; at its point of connection with the cystic duct it presents a nwell-marked constriction.
Structure—The ngall-bladder consists of three coats: serous, fibromuscular, and mucous.
The nexternal or serous coat (tunica serosa vesicae felleae) is nderived from the peritoneum; it completely invests the fundus, but covers the nbody and neck only on their under surfaces.
The nfibromuscular coat (tunica muscularis vesicae felleae), a thibut strong layer forming the frame-work of the sac, consists of dense fibrous ntissue, which interlaces in all directions, and is mixed with plain muscular nfibers, disposed chiefly in a longitudinal direction, a few running ntransversely.
The ninternal or mucous coat (tunica mucosa vesicae felleae) is nloosely connected with the fibrous layer. It is generally of a yellowish-browcolor, and is elevated into minute rugae. Opposite the neck of the gall-bladder nthe mucous membrane projects inward in the form of oblique ridges or folds, nforming a sort of spiral valve.
The nmucous membrane is continuous through the hepatic duct with the mucous membrane nlining the ducts of the liver, and through the common bile duct with the mucous nmembrane of the duodenum. It is covered with columnar epithelium, and secretes nmucin; in some animals it secretes a nucleoprotein instead of mucin.
The nCystic Duct (ductus cysticus).—The cystic duct about
The nCommon Bile Duct (ductus choledochus).—The common bile duct is nformed by the junction of the cystic and hepatic ducts; it is about
It ndescends along the right border of the lesser omentum behind the superior nportion of the duodenum, in front of the portal vein, and to the right of the nhepatic artery; it then runs in a groove near the right border of the posterior nsurface of the head of the pancreas; here it is situated in front of the ninferior vena cava, and is occasionally completely imbedded in the pancreatic nsubstance. At its termination it lies for a short distance along the right side nof the terminal part of the pancreatic duct and passes with it obliquely nbetween the mucous and muscular coats. The two ducts unite and open by a commoorifice upon the summit of the duodenal papilla, situated at the medial side of nthe descending portion of the duodenum, a little below its middle and about 7 nto
Structure.—The ncoats of the large biliary ducts are an external or fibrous, and nan internal or mucous. The fibrous coat is composed of nstrong fibroareolar tissue, with a certain amount of muscular tissue, arranged, nfor the most part, in a circular manner around the duct. The mucous coat nis continuous with the lining membrane of the hepatic ducts and gall-bladder, nand also with that of the duodenum; and, like the mucous membrane of these nstructures, its epithelium is of the columnar variety. It is provided with nnumerous mucous glands, which are lobulated and open by minute orifices nscattered irregularly in the larger ducts.
The nGallbladder is na pear-shaped, thin-walled bag, which collects up to 30–50 nml bile. We distinguish fundus, body and neck of gallbladder, nwhich continues into cystic duct. The gallbladder lies in a fossa in the nliver to which it is attached by connective tissue and covered by peritoneum nfrom below (mesoperitoneal position). The lumen of the neck of the gallbladder nand of its connections with the cystic duct is incompletely subdivided by nspiral fold of mucosa, known as the spiral fold (Heisler’s valve).
The npancreas nis the most important intestinal gland. The pancreas is shaped like a nhorizontal wedge with its thin end on the left. The head is the thickest npart, fills into the duodenal loop to the right of the spine. The horizontal body ncontinues into tail. The pancreatic duct runs right through the nlength of the gland. It receives short, vertical tributaries from the lobules nand has owns sphincter muscle of pancreatic duct. The pancreatic nduct ends together with the common bile duct on the major duodenal npapilla. If present, the accessory pancreatic duct ends above the nbile duct on the minor duodenal papilla.
Topography nof the pancreas. Pancreas lies in upper abdominal region behind the peritoneum n(retroperitoneal position) at the level of the from 1st to 3d nlumbar vertebrae. Along the upper margin of the pancreas runs the splenic nartery. The right kidney and adrenal gland adjoin to body of pancreas. Anterior nsurface of gland touches the stomach, posterior surface – inferior vena cava nand aorta. Tail adjoins to splenic hilus.
Endocrine part of pancreas is represented by nislets of Langerhans. They produce insulin and glucagon nthat regulate metabolism of carbohydrates, regulative a sugar contents iorganism. Attached to insufficient production of these hormonal disease sugar ndiabetes arises.
Theme 2. perіtoneum n(visceral and parietal sheets)
The Peritoneum (Tunica Serosa)—The peritoneum is the largest serous membrane in the body, nand consists, in the male, of a closed sac, a part of which is applied against nthe abdominal parietes, while the remainder is nreflected over the contained viscera. In the female the peritoneum is not a nclosed sac, since the free ends of the uterine tubes open directly into the nperitoneal cavity. The part which lines the parietes is named the parietal nportion of the peritoneum; that which is reflected over the contained nviscera constitutes the visceral portion of the peritoneum. The free nsurface of the membrane is smooth, covered by a layer of flattened nmesothelium, and lubricated by a small quantity of serous fluid. Hence the nviscera can glide freely against the wall of the cavity or upon one another nwith the least possible amount of friction. The attached surface is nrough, being connected to the viscera and inner surface of the parietes by nmeans of areolar tissue, termed the subserous areolar tissue. The nparietal portion is loosely connected with the fascial lining of the abdomeand pelvis, but is more closely adherent to the under surface of the diaphragm, nand also in the middle line of the abdomen.
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Vertical disposition of the nperitoneum. Main cavity, red; omental bursa, blue.
The space between the parietal and visceral layers of the nperitoneum is named the peritoneal cavity; but under normal conditions nthis cavity is merely a potential one, since the parietal and visceral layers nare in contact. The peritoneal cavity gives off a large diverticulum, the omental nbursa, which is situated behind the stomach and adjoining structures; the nneck of communication between the cavity and the bursa is termed the epiploic nforamen (foramen of Winslow). Formerly the main portion of the ncavity was described as the greater, and the omental bursa as the lesser sac.
The peritoneum differs from the other serous membranes of nthe body in presenting a much more complex arrangement, and one that can be nclearly understood only by following the changes which take place in the ndigestive tube during its development.
To trace the membrane from one viscus to another, and from nthe viscera to the parietes, it is necessary to follow its continuity in the nvertical and horizontal directions, and it will be found simpler to describe nthe main portion of the cavity and the omental bursa separately.
The PERITONEUM is nserous membrane that covers the walls of abdominal cavity and viscera iabdomen and pelvis. It may be subdivided into parietal peritoneum and visceral nperitoneum. Transition of parietal peritoneum into visceral peritoneum realizes nby derivatives: ligament, mesentery and omentum. If organ covered nby peritoneum from all sides, such position is called intraperitoneal; if from nthree sides – mesoperitoneal position; if only one side – extraperitoneal or retroperitoneal.
Abdominal ncavity is limited:
· above n- by diaphragm
· anteriorly nand laterally – by muscles, fasciae, skin
· behind n- by lumbar and sacral portions of backbone and lumbar muscles
· from nbelow – by bones, ligaments and muscles of pelvis.
Abdominal cavity contains the norgans of digestive and urogenital systems and spleen.
Peritoneal ncavity is complex of fissure betweeabdominal organs and walls lined by parietal and visceral sheets that contaiserous liquid. It can be subdivided into superior storey and inferior storey, nalso cavity of lesser pelvis.
The nabdomen is the largest cavity in the body. It is of an oval shape, the nextremities of the oval being directed upward and downward. The upper extremity nis formed by the diaphragm which extends as a dome over the abdomen, so that nthe cavity extends high into the bony thorax, reaching on the right side, ithe mammary line, to the upper border of the fifth rib; on the left side it nfalls below this level by about
The nabdomen proper differs from the other great cavities of the body ibeing bounded for the most part by muscles and fasciae, so that it can vary icapacity and shape according to the condition of the viscera which it contains; nbut, in addition to this, the abdomen varies in form and extent with age and nsex. In the adult male, with moderate distension of the viscera, it is oval ishape, but at the same time flattened from before backward. In the adult nfemale, with a fully developed pelvis, it is ovoid with the narrower pole upward, nand in young children it is also ovoid but with the narrower pole downward.
Boundaries.—It nis bounded in front and at the sides by the abdominal muscles and nthe Iliacus muscles; behind by the vertebral column and the Psoas and nQuadratus lumborum muscles; above by the diaphragm; below by the nplane of the superior aperture of the lesser pelvis. The muscles forming the nboundaries of the cavity are lined upon their inner surfaces by a layer of nfascia.
The nabdomen contains the greater part of the digestive tube; some of the accessory norgans to digestion, viz., the liver and pancreas; the spleen, the kidneys, and nthe suprarenal glands. Most of these structures, as well as the wall of the ncavity in which they are contained, are more or less covered by an extensive nand complicated serous membrane, the peritoneum.
Front nview of the thoracic and abdominal viscera. a. Median plane. b b. nLateral planes. c c. Trans tubercular plane. d d. Subcostal nplane. e e. Transpyloric plane.
The npelvis is that portion of the abdominal cavity which lies below and nbehind a plane passing through the promontory of the sacrum, lineae terminales nof the hip bones, and the pubic crests. It is bounded behind by the sacrum, ncoccyx, Piriformes, and the sacrospinous and sacrotuberous ligaments; in front nand laterally by the pubes and ischia and Obturatores interni; above it ncommunicates with the abdomen proper; below it is closed by the Levatores ani nand Coccygei and the urogenital diaphragm. The pelvis contains the urinary nbladder, the sigmoid colon and rectum, a few coils of the small intestine, and nsome of the generative organs.
Whethe anterior abdominal wall is removed, the viscera are partly exposed as nfollows: above and to the right side is the liver, situated chiefly under the nshelter of the right ribs and their cartilages, but extending across the middle nline and reaching for some distance below the level of the xiphoid process. To nthe left of the liver is the stomach, from the lower border of which aapron-like fold of peritoneum, the greater omentum, descends for a nvarying distance, and obscures, to a greater or lesser extent, the other nviscera. Below it, however, some of the coils of the small intestine cagenerally be seen, while in the right and left iliac regions respectively the ncecum and the iliac colon are partly exposed. The bladder occupies the anterior npart of the pelvis, and, if distended, will project above the symphysis pubis; nthe rectum lies in the concavity of the sacrum, but is usually obscured by the ncoils of the small intestine. The sigmoid colon lies between the rectum and the nbladder.
Whethe stomach is followed from left to right it is seen to be continuous with the nfirst part of the small intestine, or duodenum, the point of continuity being nmarked by a thickened ring which indicates the position of the pyloric valve. nThe duodenum passes toward the under surface of the liver, and then, curving ndownward, is lost to sight. If, however, the greater omentum be thrown upward nover the chest, the inferior part of the duodenum will be observed passing nacross the vertebral column toward the left side, where it becomes continuous nwith the coils of the jejunum and ileum. These measure some
The nspleen lies behind the stomach in the left hypochondriac region, and may be ipart exposed by pulling the stomach over toward the right side.
The nglistening appearance of the deep surface of the abdominal wall and of the nsurfaces of the exposed viscera is due to the fact that the former is lined, nand the latter are more or less completely covered, by a serous membrane, the peritoneum.
Transitioof parietal peritoneum into visceral peritoneum realizes by derivatives: ligament, nmesentery and omentum. If organ covered by peritoneum from all nsides, such position is called intraperitoneal; if from three sides – nmesoperitoneal position; if only one side n– extraperitoneal or retroperitoneal.
Abdominal ncavity is limited:
· nabove – by diaphragm
· nanteriorly and laterally – by muscles, fasciae, skin
· nbehind – by lumbar and sacral portions of backbone and lumbar muscles
· nfrom below – by bones, ligaments and muscles of pelvis.
Abdominal ncavity contains the organs of digestive and urogenital systems and spleen.
Regions.—For convenience of description of nthe viscera, as well as of reference to the morbid conditions of the contained nparts, the abdomen is artificially divided into nine regions by imaginary nplanes, two horizontal and two sagittal, passing through the cavity, the edges nof the planes being indicated by lines drawn on the surface of the body. Of the nhorizontal planes the upper or transpyloric is indicated by a line nencircling the body at the level of a point midway between the jugular notch nand the symphysis pubis, the lower by a line carried around the trunk at the nlevel of a point midway between the transpyloric and the symphysis pubis. The nlatter is practically the intertubercular plane of Cunningham, who npointed out 163 that its level corresponds with the prominent and easily defined ntubercle on the iliac crest about
The middle region of the upper zone is called the epigastric; nand the two lateral regions, the right and left hypochondriac. nThe central region of the middle zone is the umbilical; and the two nlateral regions, the right and left lumbar. The middle region of nthe lower zone is the hypogastric or pubic region; and the lateral nregions are the right and left iliac or inguinal.
The pelvis is that portion of the abdominal cavity nwhich lies below and behind a plane passing through the promontory of the nsacrum, lineae terminales of the hip bones, and the pubic crests. It is bounded nbehind by the sacrum, coccyx, Piriformes, and the sacrospinous and nsacrotuberous ligaments; in front and laterally by the pubes and ischia and nObturatores interni; above it communicates with the abdomen proper; below it is nclosed by the Levatores ani and Coccygei and the urogenital diaphragm. The npelvis contains the urinary bladder, the sigmoid colon and rectum, a few coils nof the small intestine, and some of the generative organs.
When the anterior abdominal wall is removed, the viscera are npartly exposed as follows: above and to the right side is the liver, situated nchiefly under the shelter of the right ribs and their cartilages, but extending nacross the middle line and reaching for some distance below the level of the nxiphoid process. To the left of the liver is the stomach, from the lower border nof which an apron-like fold of peritoneum, the greater omentum, descends nfor a varying distance, and obscures, to a greater or lesser extent, the other nviscera. Below it, however, some of the coils of the small intestine cagenerally be seen, while in the right and left iliac regions respectively the ncecum and the iliac colon are partly exposed. The bladder occupies the anterior npart of the pelvis, and, if distended, will project above the symphysis pubis; nthe rectum lies in the concavity of the sacrum, but is usually obscured by the ncoils of the small intestine. The sigmoid colon lies between the rectum and the nbladder.
When the stomach is followed from left to right it is seeto be continuous with the first part of the small intestine, or duodenum, the npoint of continuity being marked by a thickened ring which indicates the nposition of the pyloric valve. The duodenum passes toward the under surface of nthe liver, and then, curving downward, is lost to sight. If, however, the ngreater omentum be thrown upward over the chest, the inferior part of the nduodenum will be observed passing across the vertebral column toward the left nside, where it becomes continuous with the coils of the jejunum and ileum. These nmeasure some
The spleen lies behind the stomach in the left hypochondriac nregion, and may be in part exposed by pulling the stomach over toward the right nside.
The glistening appearance of the deep surface of the nabdominal wall and of the surfaces of the exposed viscera is due to the fact nthat the former is lined, and the latter are more or less completely covered, nby a serous membrane, the peritoneum.
the Peritoneum (Tunica Serosa)—The nperitoneum is the largest serous membrane in the body, and consists, in the nmale, of a closed sac, a part of which is applied against the abdominal nparietes, while the remainder is reflected over the contained viscera. In the nfemale the peritoneum is not a closed sac, since the free ends of the uterine ntubes open directly into the peritoneal cavity. The part which lines the nparietes is named the parietal portion of the peritoneum; that which is nreflected over the contained viscera constitutes the visceral portion of nthe peritoneum. The free surface of the membrane is smooth, covered by a nlayer of flattened mesothelium, and lubricated by a small quantity of serous nfluid. Hence the viscera can glide freely against the wall of the cavity or nupon one another with the least possible amount of friction. The attached nsurface is rough, being connected to the viscera and inner surface of the nparietes by means of areolar tissue, termed the subserous areolar tissue. nThe parietal portion is loosely connected with the fascial lining of the nabdomen and pelvis, but is more closely adherent to the under surface of the ndiaphragm, and also in the middle line of the abdomen.
The space between the parietal and visceral layers of the nperitoneum is named the peritoneal cavity; but under normal conditions nthis cavity is merely a potential one, since the parietal and visceral layers nare in contact. The peritoneal cavity gives off a large diverticulum, the omental nbursa, which is situated behind the stomach and adjoining structures; the nneck of communication between the cavity and the bursa is termed the epiploic nforamen (foramen of Winslow). Formerly the main portion of the ncavity was described as the greater, and the omental bursa as the lesser sac.
The peritoneum differs from the other serous membranes of nthe body in presenting a much more complex arrangement, and one that can be nclearly understood only by following the changes which take place in the ndigestive tube during its development.
To trace the membrane from one viscus to another, and from nthe viscera to the parietes, it is necessary to follow its continuity in the nvertical and horizontal directions, and it will be found simpler to describe nthe main portion of the cavity and the omental bursa separately.
Vertical Disposition of the Main Peritoneal Cavity (greater sac)—It is convenient to trace this from the back of the abdominal wall at nthe level of the umbilicus. On following the peritoneum upward from this level nit is seen to be reflected around a fibrous cord, the ligamentum teres (obliterated numbilical vein), which reaches from the umbilicus to the under surface of nthe liver. This reflection forms a somewhat triangular fold, the falciform nligament of the liver, attaching the upper and anterior surfaces of the nliver to the diaphragm and abdominal wall. With the exception of the line of nattachment of this ligament the peritoneum covers the whole of the under nsurface of the anterior part of the diaphragm, and is continued from it on to nthe upper surface of the right lobe of the liver as the superior layer of nthe coronary ligament, and on to the upper surface of the left lobe as the superior nlayer of the left triangular ligament of the liver. Covering the upper and nanterior surfaces of the liver, it is continued around its sharp margin on to nthe under surface, where it presents the following relations: (a) It ncovers the under surface of the right lobe and is reflected from the back part nof this on to the right suprarenal gland and upper extremity of the right nkidney, forming in this situation the inferior layer of the coronary nligament; a special fold, the hepatorenal ligament, is frequently npresent between the inferior surface of the liver and the front of the kidney. nFrom the kidney it is carried downward to the duodenum and right colic flexure nand medialward in front of the inferior vena cava, where it is continuous with nthe posterior wall of the omental bursa. Between the two layers of the coronary nligament there is a large triangular surface of the liver devoid of peritoneal ncovering; this is named the bare area of the liver, and is attached to nthe diaphragm by areolar tissue. Toward the right margin of the liver the two nlayers of the coronary ligament gradually approach each other, and ultimately nfuse to form a small triangular fold connecting the right lobe of the liver to nthe diaphragm, and named the right triangular ligament of the liver. The napex of the triangular bare area corresponds with the point of meeting of the ntwo layers of the coronary ligament, its base with the fossa for the inferior nvena cava. (b) It covers the lower surface of the quadrate lobe, the nunder and lateral surfaces of the gall-bladder, and the under surface and nposterior border of the left lobe; it is then reflected from the upper surface nof the left lobe to the diaphragm as the inferior layer of the left ntriangular ligament, and from the porta of the liver and the fossa for the nductus venosus to the lesser curvature of the stomach and the first
Peritoneal ncavity is complex of fissure betweeabdominal organs and walls lined by parietal and visceral sheets that contaiserous liquid. It can be subdivided into superior storey and inferior storey, nalso cavity of lesser pelvis.
Superior nstorey of peritoneal cavity positioned between diaphragm and nlevel of mesocolon of transverse colon. It contains:
• hepatic nbursa surrounds right hepatic lobe and gallbladder;
• pregastric nbursa accommodates left hepatic lobe and anterior wall of stomach;
• omental nbursa is situated behind lesser omentum and it is in touch with posterior nstomach surface.
Lesser nomentum is formed by double peritoneal sheet that forms of hepatogastric nligament and hepatoduodenal ligament. Lesser omentum carries commobile duct, portal vein and proper hepatic artery (DVA).
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Vertical disposition of nthe peritoneum. Main cavity, red; omental bursa, blue
Hepatic nbursa communicates with omental bursa by the medium of epiploic foramen (of nWinslow). Last limited from above by caudate lobe of the liver, from below – by nsuperior part of duodenum, anteriorly – hepatoduodenal ligament, behind – by nparietal sheet of peritoneum.
Greater nomentum develops from 4 peritoneal sheets, which ncontinue from gastrocolic ligament and, freely hanging down, covers the nabdominal organs in front. The gastrocolic ligament connects the ntransverse colon with the greater curvature of the stomach.
Inferior nfloor of peritoneal cavity extends from mesocolon of ntransverse colon to entrance into lesser pelvis.
Root nof small intestine mesentery divides the inferior storey into right and nleft mesenteric sinuses. They naccommodate the loops of small intestine. Right mesenteric sinus is bordered by nmesenteric root and ascending colon. In place, where ileum continues into cecum nsuperior and inferior ileocecal recesses are situated. One casee retrocecal recess behind cecum. Right paracolic sulcus runs nbetween ascending colon and parietal peritoneum of lateral abdominal wall. nMesenteric root, descending colon and sigmoid colon border left mesenteric nsinus. Superior and inferior duodenal recesses are positioned nin area of duodenojejunal junction. Mesocolon of sigmoid forms intersigmoidal nrecess. Left paracolic sulcus runs between descending colon and nparietal peritoneum of left abdominal wall.
Parietal nsheet of peritoneum covering back surface of anterior abdominal form plicae n(folds) and fossae. The median umbilical nfold contains the remnant of the embryonic urachus; the medial umbilical nfolds carry obliterated umbililal arteries; lateral umbilical folds ncontain inferior epigastric arteries. Supravesical fossae positioned nbetween median and medial umbilical folds. Medial umbilical fossae nlocated between medial and lateral umbilical folds. Lateral umbilical fossae nlocated laterally from lateral umbilical folds. Medial and lateral umbilical nfossae can be projected into superficial inguinal ring and deep inguinal nring.
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Posterior view of the nanterior abdominal wall in its lower half. The peritoneum is in place, and the nvarious cords are shining through
Cavity nof lesser pelvis
Peritoneal cavity in the male pelvis ncontains rectovesical excavation (pouch). Peritoneum in the female nbetween uterus and urinary bladder form vesicouterinae excavation. Behind nthe uterus peritoneum descends into the rectouterine pouch (pouch of Douglas ), which is the lowest point of the peritoneal ncavity. That is why some liquid from all peritoneal cavity can collect here nduring some pathology. The entrance into the rectouterine pouch is narrowed by nthe rectouterine folds, in which the rectouterine muscles run.
Theme 3. External nose. nasal cavity. larynx.
The respiratory apparatus consists of the nose, nasal cavity, larynx, ntrachea, bronchi, lungs, and pleurae.
The head and neck of a human embryo nthirty-two days old, seen from the ventral surface. The floor of the mouth and npharynx have been removed
Lungs of a human embryo more advanced idevelopment.
External nose and the nasal cavity, which is divided by a septum into right nand left nasal chambers.
External Nose (Nasus Externus; Outer Nose) is pyramidal iform, and its upper angle or root is connected directly with the nforehead; its free angle is termed the apex. Its base is nperforated by two elliptical orifices, the nares, separated from each nother by an antero-posterior septum, the columna. The margins of the nnares are provided with a number of stiff hairs, or vibrissae, which narrest the passage of foreign substances carried with the current of air nintended for respiration. The lateral surfaces of the nose form, by their unioin the middle line, the dorsum nasi, the direction of which varies nconsiderably in different individuals; the upper part of the dorsum is supported nby the nasal bones, and is named the bridge. The lateral surface ends nbelow in a rounded eminence, the ala nasi.
Structure.—The frame-work of the nexternal nose is composed of bones and cartilages; it is covered by the nintegument, and lined by mucous membrane.
The bony frame-work occupies the upper part of the norgan; it consists of the nasal bones, and the frontal processes of the maxillae.
The cartilaginous frame-work (cartilagines nasi) nconsists of five large pieces, viz., the cartilage of the septum, the two nlateral and the two greater alar cartilages, and several smaller npieces, the lesser alar cartilages. The various cartilages are connected nto each other and to the bones by a tough fibrous membrane.
The cartilage of the septum (cartilago septi nasi) nis somewhat quadrilateral in form, thicker at its margins than at its center, nand completes the separation between the nasal cavities in front. Its anterior nmargin, thickest above, is connected with the nasal bones, and is continuous nwith the anterior margins of the lateral cartilages; below, it is connected to nthe medial crura of the greater alar cartilages by fibrous tissue. Its nposterior margin is connected with the perpendicular plate of the ethmoid; its ninferior margin with the vomer and the palatine processes of the maxillae.
It may be prolonged backward (especially in children) as a nnarrow process, the sphenoidal process, for some distance between the nvomer and perpendicular plate of the ethmoid. The septal cartilage does not nreach as far as the lowest part of the nasal septum. This is formed by the nmedial crura of the greater alar cartilages and by the skin; it is freely nmovable, and hence is termed the septum mobile nasi.
The lateral cartilage (cartilago nasi lateralis; nupper lateral cartilage) is situated below the inferior margin of the nasal nbone, and is flattened, and triangular in shape. Its anterior margin is thicker nthan the posterior, and is continuous above with the cartilage of the septum, nbut separated from it below by a narrow fissure; its superior margin is nattached to the nasal bone and the frontal process of the maxilla; its inferior nmargin is connected by fibrous tissue with the greater alar cartilage.
The greater alar cartilage (cartilago alaris nmajor; lower lateral cartilage) is a thin, flexible plate, situated nimmediately below the preceding, and bent upon itself in such a manner as to nform the medial and lateral walls of the naris of its own side. The portiowhich forms the medial wall (crus mediale) is loosely connected nwith the corresponding portion of the opposite cartilage, the two forming, ntogether with the thickened integument and subjacent tissue, the septum nmobile nasi. The part which forms the lateral wall (crus laterale) nis curved to correspond with the ala of the nose; it is oval and flattened, nnarrow behind, where it is connected with the frontal process of the maxilla by na tough fibrous membrane, in which are found three or four small cartilaginous nplates, the lesser alar cartilages (cartilagines alares minores; nsesamoid cartilages). Above, it is connected by fibrous tissue to the nlateral cartilage and front part of the cartilage of the septum; below, it nfalls short of the margin of the naris, the ala being completed by fatty and nfibrous tissue covered by skin. In front, the greater alar cartilages are nseparated by a notch which corresponds with the apex of the nose.
Cartilages of the nose. Side view.
Cartilages of the nose, seen from below.
Bones and cartilages of septum of nose. nRight side.
The muscles acting on the external nose have been described nin the section on Myology.
The integument of the dorsum and sides of the nose is nthin, and loosely connected with the subjacent parts; but over the tip and alae nit is thicker and more firmly adherent, and is furnished with a large number of nsebaceous follicles, the orifices of which are usually very distinct.
Nasal Cavity (Cavum Nasi; Nasal Fossa)—The nasal chambers are situated one on either side of the nmedian plane. They open in front through the nares, and communicate behind nthrough the choanae with the nasal part of the pharynx. The nares are nsomewhat pear-shaped apertures, each measuring about
Inside the aperture of the nostril is a slight ndilatation, the vestibule, bounded laterally by the ala and lateral crus nof the greater alar cartilage, and medially by the medial crus of the same ncartilage. It is lined by skin containing hairs and sebaceous glands, and nextends as a small recess toward the apex of the nose. Each nasal cavity, above nand behind the vestibule, is divided into two parts: an olfactory region, nconsisting of the superior nasal concha and the opposed part of the septum, and na respiratory region, which comprises the rest of the cavity.
Lateral wall of nasal cavity.
Lateral Wall—On nthe lateral wall are the superior, middle, and inferior nasal conchae, nand below and lateral to each concha is the corresponding nasal passage or nmeatus. Above the superior concha is a narrow recess, the sphenoethmoidal nrecess, into which the sphenoidal sinus opens. The superior meatus nis a short oblique passage extending about half-way along the upper border of nthe middle concha; the posterior ethmoidal cells open into the front part of nthis meatus. The middle meatus is below and lateral to the middle nconcha, and is continued anteriorly into a shallow depression, situated above nthe vestibule and named the atrium of the middle meatus. On raising or nremoving the middle concha the lateral wall of this meatus is fully displayed. nOn it is a rounded elevation, the bulla ethmoidalis, and below and ifront of this is a curved cleft, the hiatus semilunaris.
The bulla ethmoidalis is caused by the bulging of the middle nethmoidal cells which open on or immediately above it, and the size of the nbulla varies with that of its contained cells.
The hiatus semilunaris is bounded inferiorly by the nsharp concave margin of the uncinate process of the ethmoid bone, and leads ninto a curved channel, the infundibulum, bounded above by the bulla nethmoidalis and below by the lateral surface of the uncinate process of the nethmoid. The anterior ethmoidal cells open into the front part of the ninfundibulum, and this in slightly over 50 per cent. of subjects is directly ncontinuous with the frontonasal duct or passage leading from the frontal air nsinus; but when the anterior end of the uncinate process fuses with the front npart of the bulla, this continuity is interrupted and the frontonasal duct theopens directly into the anterior end of the middle meatus.
Below the bulla ethmoidalis, and partly hidden by the ninferior end of the uncinate process, is the ostium maxillare, or nopening from the maxillary sinus; in a frontal section this opening is seen to nbe placed near the roof of the sinus. An accessory opening from the sinus is nfrequently present below the posterior end of the middle nasal concha. The inferior nmeatus is below and lateral to the inferior nasal concha; the nasolacrimal nduct opens into this meatus under cover of the anterior part of the inferior nconcha.
Medial Wall or septum is nfrequently more or less deflected from the median plane, thus lessening the nsize of one nasal cavity and increasing that of the other; ridges or spurs of nbone growing into one or other cavity from the septum are also sometimes npresent. Immediately over the incisive canal at the lower edge of the cartilage nof the septum a depression, the nasopalatine recess, is seen. In the nseptum close to this recess a minute orifice may be discerned; it leads nbackward into a blind pouch, the rudimentary vomeronasal organ of Jacobson, nwhich is supported by a strip of cartilage, the vomeronasal cartilage. nThis organ is well-developed in many of the lower animals, where it apparently nplays a part in the sense of smell, since it is supplied by twigs of the nolfactory nerve and lined by epithelium similar to that in the olfactory regioof the nose.
The roof of the nasal cavity is narrow from side to nside, except at its posterior part, and may be divided, from behind forward, ninto sphenoidal, ethmoidal, and frontonasal parts, after the bones which form nit.
The floor is concave from side to side and almost nhorizontal antero-posteriorly; its anterior three-fourths are formed by the npalatine process of the maxilla, its posterior fourth by the horizontal process nof the palatine bone. In its anteromedial part, directly over the incisive nforamen, a small depression, the nasopalatine recess, is sometimes seen; nit points downward and forward and occupies the position of a canal which nconnected the nasal with the buccal cavity in early fetal life.
The Mucous Membrane (membrana mucosa nasi).—The nasal mucous membrane lines the nasal cavities, and is intimately nadherent to the periosteum or perichondrium. It is continuous with the skithrough the nares, and with the mucous membrane of the nasal part of the npharynx through the choanae. From the nasal cavity its continuity with the nconjunctiva may be traced, through the nasolacrimal and lacrimal ducts; and nwith the frontal, ethmoidal, sphenoidal, and maxillary sinuses, through the nseveral openings in the meatuses. The mucous membrane is thickest, and most nvascular, over the nasal conchae. It is also thick over the septum; but it is nvery thin in the meatuses on the floor of the nasal cavities, and in the nvarious sinuses.
Owing to the thickness of the greater part of this membrane, nthe nasal cavities are much narrower, and the middle and inferior nasal conchae nappear larger and more prominent than in the skeleton; also the various napertures communicating with the meatuses are considerably narrowed.
The olfactory, the special nerve of the sense of nsmell, is distributed to the olfactory region. Its fibers arise from the nbipolar olfactory cells and are destitute of medullary sheaths. They unite ifasciculi which form a plexus beneath the mucous membrane and then ascend igrooves or canals in the ethmoid bone; they pass into the skull through the nforamina in the cribriform plate of the ethmoid and enter the under surface of nthe olfactory bulb, in which they ramify and form synapses with the dendrites nof the mitral cells.
Nerves of septum of nose. Right side
The Accessory Sinuses of the Nose (Sinus Paranasales)
The accessory sinuses or air cells of the nose nare the frontal, ethmoidal, sphenoidal, and maxillary; they vary nin size and form in different individuals, and are lined by ciliated mucous nmembrane directly continuous with that of the nasal cavities.
The Frontal Sinuses (sinus frontales), nsituated behind the superciliary arches, are rarely symmetrical, and the septum nbetween them frequently deviates to one or other side of the middle line. Their naverage measurements are as follows: height,
Coronal section of nasal cavities.
The Ethmoidal Air Cells (cellulae ethmoidales) nconsist of numerous thin-walled cavities situated in the ethmoidal labyrinth nand completed by the frontal, maxilla, lacrimal, sphenoidal, and palatine. They nlie between the upper parts of the nasal cavities and the orbits, and are nseparated from these cavities by thin bony laminae. On either side they are narranged in three groups, anterior, middle, and posterior. The nanterior and middle groups open into the middle meatus of the nose, the former nby way of the infundibulum, the latter on or above the bulla ethmoidalis. The nposterior cells open into the superior meatus under cover of the superior nasal nconcha; sometimes one or more opens into the sphenoidal sinus. The ethmoidal ncells begin to develop during fetal life.
The Sphenoidal Sinuses (sinus sphenoidales) ncontained within the body of the sphenoid vary in size and shape; owing to the nlateral displacement of the intervening septum they are rarely symmetrical. The nfollowing are their average measurements: vertical height,
Specimen from a child eight days old. By nsagittal sections removing the lateral portion of frontal bone, lamina npapyracea of ethmoid, and lateral portion of nmaxilla—the sinus maxillaris, cellulae ethmoidales, anterior and posterior, ninfundibulum ethmoidale, and the primitive sinus frontalis are brought into nview.
Specimen from a child one year, four nmonths, and seven days old. Lateral view of frontal, ethmoidal, and maxillary nsinus areas.
The Maxillary Sinus (sinus maxillaris; antrum of nHighmore), the largest of the accessory sinuses of the nose, is a pyramidal ncavity in the body of the maxilla. Its base is formed by the lateral wall of nthe nasal cavity, and its apex extends into the zygomatic process. Its roof or norbital wall is frequently ridged by the infra-orbital canal, while its floor nis formed by the alveolar process and is usually 1/2 to
Specimen from a child eight years, eight months, and one day old. nLateral view of frontal, ethmoidal and maxillary sinus areas, the lateral nportion of each having been removed by sagittal cuts. Note that the sinus nfrontalis developed directly from the infundibulum ethmoidale.
Note also the incomplete septa in the sinus maxillaris.
The Larynx is nsituated in anterior neck area on level IV-VI cervical vertebrae. At the front ninfrahyoid muscles of neck cover it. Vessels and nervous bundles and lobes of nthyroid gland lie from sides of larynx. Laryngeal part of pharynx adjoins nbehind it.
Larynx nskeleton consists of pair and odd cartilages.
Odd ncartilages:
• Thyroid ncartilage, which consists of right and left plates (lamina dextra et nsinistra), and also has superior horns and inferior horns; the plates converge nforming laryngeal prominence (Adam’s apple);
• Cricoid ncartilage which has anteriorly arch behind – plate of cricoid cartilage;
• Epiglottis ncartilage.
The cartilages of the larynx. Posterior view.
Paired ncartilages:
• Arytenoid ncartilage, which has a base and apex, muscular process and vocal process. These ncartilage lie on plate of cricoid cartilage;
• Corniculate ncartilage lies in aryepiglottic fold on top of arytenoid cartilages;
• Cuneiform ncartilage lies in aryepiglottic fold front of corniculate cartilages.
Ilarynx they distinguish such articulations:
• Cricoid-thyroid njoint is between inferior cornu of thyroid cartilage and arch of cricoid ncartilage; in this joint movement is possible around transversal axis;
• Cricoid-arytenoid njoint is situated between base of arytenoid cartilages and plate of cricoid ncartilage. Arytenoid cartilage can rotate slide to meet one another.
Ligaments nof the larynx:
• nThyro-hyoid membrane, which hangs larynx to hyoid bone;
• nCrico-thyroid ligament;
• nThyro-epiglottic ligament;
• nHyoepiglottic ligament;
• nVestibular ligaments, which are situated over vocal ligaments.
The ligaments of the larynx. Antero-lateral view.
Fibroelastic nmembrane the larynx:
· Elastic ncone contains iits superior margin vocal ligament;
· Quadrangular nmembrane, which is situated over elastic cone and in its ninferior margin contains vestibular ligament.
Fibroelastic nmembranes together with laryngeal cartilages form a laryngeal skeleton.
The nlaryngeal Muscles subdivide on muscles that narrow/broaden the glottis, muscles nthat change tension of vocal ligament.
Constrictors nof the glottis:
· lateral ncricoarytenoid muscle;
· thyroarytenoid nmuscle;
· transverse narytenoid muscle;
· oblique narytenoid muscles.
Muscles-dilators nof the glottis
• thyro-arytenoid nmuscle has thyro-epiglottic part. Action: it raises the epiglottis and nbroadens an entrance into larynx and vestibule.
• posterior ncricoid-arytenoid muscle.
Muscles nchanging tension of vocal ligament:
• crico-thyroid nmuscle stretches a vocal ligament.
• vocal nmuscle is situated in thickness of vocal fold and changes an tension degree nof vocal cords.
Laryngeal ncavity has aditus laryngis [entrance], vestibule, ninterventricular space, glottis and infraglottic cavity.
Larynx nhas true vocal folds and glottis. Larynx begins by entrance ninto larynx, which is limited at the front, by epiglottis, behind – by arytenoid ncartilages, and laterally – by arytenoepiglottic folds, where cuneiform and ncorniculate tubercles are situated (places of the same name cartilages). Glottis nis a most narrow place in laryngeal cavity; it is situated between right and nleft vocal plicae. Laryngeal ventricle is fissure disposed between vocal nand vestibular plicae.
Infraglottic ncavity is inferior broadened part of larynx, which continues ninto trachea.
The larynx or organ of voice is placed at the upper part of nthe air passage. It is situated between the trachea and the root of the tongue, nat the upper and forepart of the neck, where it presents a considerable nprojection in the middle line. It forms the lower part of the anterior wall of nthe pharynx, and is covered behind by the mucous lining of that cavity; oeither side of it lie the great vessels of the neck. Its vertical extent ncorresponds to the fourth, fifth, and sixth cervical vertebrae, but it is nplaced somewhat higher in the female and also during childhood. Symington found nthat in infants between six and twelve months of age the tip of the epiglottis nwas a little above the level of the fibrocartilage between the odontoid process nand body of the axis, and that between infancy and adult life the larynx descends nfor a distance equal to two vertebral bodies and two intervertebral nfibrocartilages. According to Sappey the average measurements of the adult nlarynx are as follows:
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Until puberty the larynx of the male differs little in size from that of nthe female. In the female its increase after puberty is only slight; in the nmale it undergoes considerable increase; all the cartilages are enlarged and nthe thyroid cartilage becomes prominent in the middle line of the neck, while nthe length of the rima glottidis is nearly doubled.
The larynx is broad above, where it presents the form of a triangular nbox flattened behind and at the sides, and bounded in front by a prominent nvertical ridge. Below, it is narrow and cylindrical. It is composed of ncartilages, which are connected together by ligaments and moved by numerous nmuscles. It is lined by mucous membrane continuous above with that of the npharynx and below with that of the trachea.
The Cartilages of the Larynx (cartilagines laryngis) are nnine iumber, three single and three paired, as follows:
Thyroid.
Cricoid.
Two Arytenoid.
Two Corniculate.
Two Cuneiform. Epiglottis
The Thyroid Cartilage (cartilago thyreoidea) is the nlargest cartilage of the larynx. It consists of two laminae the anterior nborders of which are fused with each other at an acute angle in the middle line nof the neck, and form a subcutaneous projectioamed the laryngeal nprominence (pomum Adami). This prominence is most distinct at its nupper part, and is larger in the male than in the female. Immediately above it nthe laminae are separated by a V-shaped notch, the superior thyroid notch. nThe laminae are irregularly quadrilateral in shape, and their posterior angles nare prolonged into processes termed the superior and inferior cornua.
The outer surface of each lamina presents an oblique line nwhich runs downward and forward from the superior thyroid tubercle situated nnear the root of the superior cornu, to the inferior thyroid tubercle on the nlower border. This line gives attachment to the Sternothyreoideus, nThyreohyoideus, and Constrictor pharyngis inferior.
The inner surface is smooth; above and behind, it is slightly nconcave and covered by mucous membrane. In front, in the angle formed by the njunction of the laminae, are attached the stem of the epiglottis, the nventricular and vocal ligaments, the Thyreoarytaenoidei, Thyreoepiglottici and nVocales muscles, and the thyroepiglottic ligament.
The upper border is concave behind and convex in front; it gives nattachment to the corresponding half of the hyothyroid membrane.
The lower border is concave behind, and nearly straight in front, nthe two parts being separated by the inferior thyroid tubercle. A small part of nit in and near the middle line is connected to the cricoid cartilage by the nmiddle cricothyroid ligament.
The posterior border, thick and rounded, receives the insertions nof the Stylopharyngeus and Pharyngopalatinus. It ends above, in the superior ncornu, and below, in the inferior cornu. The superior cornu is long and nnarrow, directed upward, backward, and medialward, and ends in a conical nextremity, which gives attachment to the lateral hyothyroid ligament. The inferior ncornu is short and thick; it is directed downward, with a slight ninclination forward and medialward, and presents, on the medial side of its ntip, a small oval articular facet for articulation with the side of the cricoid ncartilage.
During infancy the laminae of the thyroid cartilage are joined to each nother by a narrow, lozenge-shaped strip, named the intrathyroid cartilage. nThis strip extends from the upper to the lower border of the cartilage in the nmiddle line, and is distinguished from the laminae by being more transparent nand more flexible.
The Cricoid Cartilage (cartilago cricoidea) is smaller, nbut thicker and stronger than the thyroid, and forms the lower and posterior nparts of the wall of the larynx. It consists of two parts: a posterior nquadrate lamina, and a narrow anterior arch, one-fourth or one-fifth nof the depth of the lamina.
The lamina (lamina cartilaginis cricoideae; posterior portion) nis deep and broad, and measures from above downward about 2 or
The arch (arcus cartilaginis cricoideae; anterior portion) nis narrow and convex, and measures vertically from 5 to
On either side, at the junction of the lamina with the arch, is a small nround articular surface, for articulation with the inferior cornu of the nthyroid cartilage.
The lower border of the cricoid cartilage is horizontal, and nconnected to the highest ring of the trachea by the cricotracheal ligament.
The upper border runs obliquely upward and backward, owing to the ngreat depth of the lamina. It gives attachment, in front, to the middle ncricothyroid ligament; at the side, to the conus elasticus and the Cricoarytaenoidei nlaterales; behind, it presents, in the middle, a shallow notch, and on either nside of this is a smooth, oval, convex surface, directed upward and nlateralward, for articulation with the base of an arytenoid cartilage.
The inner surface of the cricoid cartilage is smooth, and lined nby mucous membrane.
The Arytenoid Cartilages (cartilagines arytaenoideae) are ntwo iumber, and situated at the upper border of the lamina of the cricoid ncartilage, at the back of the larynx. Each is pyramidal in form, and has three nsurfaces, a base, and an apex.
The posterior surface is a triangular, smooth, concave, and gives nattachment to the Arytaenoidei obliquus and transversus.
The antero-lateral surface is somewhat convex and rough. On it, nnear the apex of the cartilage, is a rounded elevation (colliculus) from nwhich a ridge (crista arcuata) curves at first backward and thedownward and forward to the vocal process. The lower part of this crest nintervenes between two depressions or foveae, an upper, triangular, and na lower oblong in shape; the latter gives attachment to the Vocalis muscle.
The medial surface is narrow, smooth, and flattened, covered by nmucous membrane, and forms the lateral boundary of the intercartilaginous part nof the rima glottidis.
The base of each cartilage is broad, and on it is a concave nsmooth surface, for articulation with the cricoid cartilage. Its lateral angle nis short, rounded, and prominent; it projects backward and lateralward, and is ntermed the muscular process; it gives insertion to the Cricoarytaenoideus nposterior behind, and to the Cricoarytaenoideus lateralis in front. Its nanterior angle, also prominent, but more pointed, projects horizontally nforward; it gives attachment to the vocal ligament, and is called the vocal nprocess.
The apex of each cartilage is pointed, curved backward and nmedialward, and surmounted by a small conical, cartilaginous nodule, the corniculate ncartilage.
The Corniculate Cartilages (cartilagines corniculatae; ncartilages of Santorini) are two small conical nodules consisting of yellow nelastic cartilage, which articulate with the summits of the arytenoid ncartilages and serve to prolong them backward and medialward. They are situated nin the posterior parts of the aryepiglottic folds of mucous membrane, and are nsometimes fused with the arytenoid cartilages.
The Cuneiform Cartilages (cartilagines cuneiformes; cartilages nof Wrisberg) are two small, elongated pieces of yellow elastic cartilage, nplaced one on either side, in the aryepiglottic fold, where they give rise to nsmall whitish elevations on the surface of the mucous membrane, just in front nof the arytenoid cartilages.
The Epiglottis (cartilago epiglottica) is a thin lamella nof fibrocartilage of a yellowish color, shaped like a leaf, and projecting nobliquely upward behind the root of the tongue, in front of the entrance to the nlarynx. The free extremity is broad and rounded; the attached part or stem is nlong, narrow, and connected by the thyroepiglottic ligament to the angle nformed by the two laminae of the thyroid cartilage, a short distance below the nsuperior thyroid notch. The lower part of its anterior surface is connected to nthe upper border of the body of the hyoid bone by an elastic ligamentous band, nthe hyoepiglottic ligament.
The anterior or lingual surface is curved forward, and ncovered on its upper, free part by mucous membrane which is reflected on to the nsides and root of the tongue, forming a median and two lateral glossoepiglottic nfolds; the lateral folds are partly attached to the wall of the pharynx. nThe depressions between the epiglottis and the root of the tongue, on either nside of the median fold, are named the valleculae. The lower part of the nanterior surface lies behind the hyoid bone, the hyothyroid membrane, and upper npart of the thyroid cartilage, but is separated from these structures by a mass nof fatty tissue.
The posterior or laryngeal surface is smooth, concave from nside to side, concavo-convex from above downward; its lower part projects nbackward as an elevation, the tubercle or cushion. When the nmucous membrane is removed, the surface of the cartilage is seen to be indented nby a number of small pits, in which mucous glands are lodged. To its sides the naryepiglottic folds are attached.
Structure.—The corniculate and ncuneiform cartilages, the epiglottis, and the apices of the arytenoids at first nconsist of hyaline cartilage, but later elastic fibers are deposited in the nmatrix, converting them into yellow fibrocartilage, which shows little tendency nto calcification. The thyroid, cricoid, and the greater part of the arytenoids nconsist of hyaline cartilage, and become more or less ossified as age advances. nOssification commences about the twenty-fifth year in the thyroid cartilage, nand somewhat later in the cricoid and arytenoids; by the sixty-fifth year these ncartilages may be completely converted into bone.
Ligaments.—The ligaments of the nlarynxare extrinsic, i. e., those connecting the thyroid ncartilage and epiglottis with the hyoid bone, and the cricoid cartilage with the ntrachea; and intrinsic, those which connect the several cartilages of nthe larynx to each other.
Extrinsic Ligaments.—The ligaments nconnecting the thyroid cartilage with the hyoid bone are the hyothyroid nmembrane, and a middle and two lateral hyothyroid ligaments.
The Hyothyroid Membrane (membrana hyothyreoidea; thyrohyoid nmembrane) is a broad, fibro-elastic layer, attached below to the upper nborder of the thyroid cartilage and to the front of its superior cornu, and nabove to the upper margin of the posterior surface of the body and greater ncornua of the hyoid bone, thus passing behind the posterior surface of the body nof the hyoid, and being separated from it by a mucous bursa, which facilitates nthe upward movement of the larynx during deglutition. Its middle thicker part nis termed the middle hyothyroid ligament (ligamentum hyothyreoideum nmedium; middle thyrohyoid ligament), its lateral thinner portions are npierced by the superior laryngeal vessels and the internal branch of the nsuperior laryngeal nerve. Its anterior surface is in relation with the nThyreohyoideus, Sternohyoideus, and Omohyoideus, and with the body of the hyoid nbone.
The Lateral Hyothyroid Ligament (ligamentum hyothyreoideum nlaterale; lateral thyrohyoid ligament) is a round elastic cord, which forms nthe posterior border of the hyothyroid membrane and passes between the tip of nthe superior cornu of the thyroid cartilage and the extremity of the greater ncornu of the hyoid bone. A small cartilaginous nodule (cartilago triticea), nsometimes bony, is frequently found in it.
Ligaments of the larynx. Posterior view.
The Epiglottis is connected with the hyoid bone by an elastic nband, the hyoepiglottic ligament (ligamentum hyoepiglotticum), nwhich extends from the anterior surface of the epiglottis to the upper border nof the body of the hyoid bone. The glossoepiglottic folds of mucous membrane n(page 1075) may also be considered as extrinsic ligaments of the epiglottis.
The Cricotracheal Ligament (ligamentum cricotracheale) nconnects the cricoid cartilage with the first ring of the trachea. It resembles nthe fibrous membrane which connects the cartilaginous rings of the trachea to neach other.
Intrinsic Ligaments.—Beneath the mucous nmembrane of the larynx is a broad sheet of fibrous tissue containing many nelastic fibers, and termed the elastic membrane of the larynx. It is nsubdivided on either side by the interval between the ventricular and vocal nligaments, the upper portion extends between the arytenoid cartilage and the nepiglottis and is often poorly defined; the lower part is a well-marked nmembrane forming, with its fellow of the opposite side, the conus elasticus nwhich connects the thyroid, cricoid, and arytenoid cartilages to one another. nIn addition the joints between the individual cartilages are provided with nligaments.
The Conus Elasticus (cricothyroid membrane) is composed nmainly of yellow elastic tissue. It consists of an anterior and two lateral nportions. The anterior part or middle cricothyroid ligament (ligamentum ncricothyreoideum medium; central part of cricothyroid membrane) is thick nand strong, narrow above and broad below. It connects together the front parts nof the contiguous margins of the thyroid and cricoid cartilages. It is noverlapped on either side by the Cricothyreoideus, but between these is nsubcutaneous; it is crossed horizontally by a small anastomotic arterial arch, nformed by the junction of the two cricothyroid arteries, branches of which npierce it. The lateral portions are thinner and lie close under the nmucous membrane of the larynx; they extend from the superior border of the ncricoid cartilage to the inferior margin of the vocal ligaments, with which nthey are continuous. These ligaments may therefore be regarded as the free nborders of the lateral portions of the conus elasticus, and extend from the nvocal processes of the arytenoid cartilages to the angle of the thyroid ncartilage about midway between its upper and lower borders.
An articular capsule, strengthened posteriorly by a well-marked nfibrous band, encloses the articulation of the inferior cornu of the thyroid nwith the cricoid cartilage on either side.
Each arytenoid cartilage is connected to the cricoid by a capsule and a nposterior cricoarytenoid ligament. The capsule (capsula articularis ncricoarytenoidea) is thin and loose, and is attached to the margins of the narticular surfaces. The posterior cricoarytenoid ligament (ligamentum ncricoarytenoideum posterius) extends from the cricoid to the medial and back npart of the base of the arytenoid.
The thyroepiglottic ligament (ligamentum thyreoepiglotticum) nis a long, slender, elastic cord which connects the stem of the epiglottis with nthe angle of the thyroid cartilage, immediately beneath the superior thyroid nnotch, above the attachment of the ventricular ligaments.
Movements.—The articulatiobetween the inferior cornu of the thyroid cartilage and the cricoid cartilage non either side is a diarthrodial one, and permits of rotatory and gliding nmovements. The rotatory movement is one in which the cricoid cartilage rotates nupon the inferior cornua of the thyroid cartilage around an axis passing ntransversely through both joints. The gliding movement consists in a limited nshifting of the cricoid on the thyroid in different directions.
The articulation between the arytenoid cartilages and the cricoid is nalso a diarthrodial one, and permits of two varieties of movement: one is a nrotation of the arytenoid on a vertical axis, whereby the vocal process is nmoved lateralward or medialward, and the rima glottidis increased or ndiminished; the other is a gliding movement, and allows the arytenoid ncartilages to approach or recede from each other; from the direction and slope nof the articular surfaces lateral gliding is accompanied by a forward and ndownward movement. The two movements of gliding and rotation are associated, nthe medial gliding being connected with medialward rotation, and the lateral ngliding with lateralward rotation. The posterior cricoarytenoid ligaments limit nthe forward movement of the arytenoid cartilages on the cricoid.
Interior of the Larynx—The cavity of the nlarynx (cavum laryngis) extends from the laryngeal entrance to the nlower border of the cricoid cartilage where it is continuous with that of the ntrachea. It is divided into two parts by the projection of the vocal folds, nbetween which is a narrow triangular fissure or chink, the rima glottidis. nThe portion of the cavity of the larynx above the vocal folds is called the vestibule; nit is wide and triangular in shape, its base or anterior wall presenting, nhowever, about its center the backward projection of the tubercle of the nepiglottis. It contains the ventricular folds, and between these and the vocal nfolds are the ventricles of the larynx. The portion below the vocal nfolds is at first of an elliptical form, but lower down it widens out, assumes na circular form, and is continuous with the tube of the trachea.
The entrance of the larynx is a triangular opening, wide ifront, narrow behind, and sloping obliquely downward and backward. It is nbounded, in front, by the epiglottis; behind, by the apices of the arytenoid ncartilages, the corniculate cartilages, and the interarytenoid notch; and oeither side, by a fold of mucous membrane, enclosing ligamentous and muscular nfibers, stretched between the side of the epiglottis and the apex of the narytenoid cartilage; this is the aryepiglottic fold, on the posterior npart of the margin of which the cuneiform cartilage forms a more or less ndistinct whitish prominence, the cuneiform tubercle.
Sagittal section of the larynx and upper part of the trachea
The Ventricular Folds (plicœ ventriculares; superior or nfalse vocal cords) are two thick folds of mucous membrane, each enclosing a nnarrow band of fibrous tissue, the ventricular ligament which is nattached in front to the angle of the thyroid cartilage immediately below the nattachment of the epiglottis, and behind to the antero-lateral surface of the narytenoid cartilage, a short distance above the vocal process. The lower border nof this ligament, enclosed in mucous membrane, forms a free crescentic margin, nwhich constitutes the upper boundary of the ventricle of the larynx.
The Vocal Folds (plicœ vocales; inferior or true vocal ncords) are concerned in the production of sound, and enclose two strong nbands, named the vocal ligaments (ligamenta vocales; inferior nthyroarytenoid). Each ligament consists of a band of yellow elastic tissue, nattached in front to the angle of the thyroid cartilage, and behind to the nvocal process of the arytenoid. Its lower border is continuous with the thilateral part of the conus elasticus. Its upper border forms the lower boundary nof the ventricle of the larynx. Laterally, the Vocalis muscle lies parallel nwith it. It is covered medially by mucous membrane, which is extremely thin and nclosely adherent to its surface.
Coronal section of larynx and upper part of trachea.
The Ventricle of the Larynx (ventriculus laryngis [Morgagnii]; nlaryngeal sinus) is a fusiform fossa, situated between the ventricular nand vocal folds on either side, and extending nearly their entire length. The nfossa is bounded, above, by the free crescentic edge of the ventricular nfold; below, by the straight margin of the vocal fold; laterally, nby the mucous membrane covering the corresponding Thyreoarytaenoideus. The nanterior part of the ventricle leads up by a narrow opening into a cecal pouch nof mucous membrane of variable size called the appendix.
The appendix of the laryngeal ventricle (appendix ventriculi nlaryngis; laryngeal saccule) is a membranous sac, placed between the nventricular fold and the inner surface of the thyroid cartilage, occasionally nextending as far as its upper border or even higher; it is conical in form, and ncurved slightly backward. On the surface of its mucous membrane are the nopenings of sixty or seventy mucous glands, which are lodged in the submucous nareolar tissue. This sac is enclosed in a fibrous capsule, continuous below nwith the ventricular ligament. Its medial surface is covered by a few delicate nmuscular fasciculi, which arise from the apex of the arytenoid cartilage nand become lost in the aryepiglottic fold of mucous membrane; laterally it is nseparated from the thyroid cartilage by the Thyreoepiglotticus. These muscles ncompress the sac, and express the secretion it contains upon the vocal folds to nlubricate their surfaces.
The entrance to the larynx, viewed from behind.
The Rima Glottidis is the elongated fissure or chink between the nvocal folds in front, and the bases and vocal processes of the arytenoid ncartilages behind. It is therefore subdivided into a larger anterior nintramembranous part (glottis vocalis), which measures about nthree-fifths of the length of the entire aperture, and a posterior nintercartilaginous part (glottis respiratoria). Posteriorly it is nlimited by the mucous membrane passing between the arytenoid cartilages. The nrima glottidis is the narrowest part of the cavity of the larynx, and its level ncorresponds with the bases of the arytenoid cartilages. Its length, in the nmale, is about
Laryngoscopic view of interior of larynx.)
Muscles.—The muscles of the larynx are extrinsic, npassing between the larynx and parts around—these have been described in the nsection on Myology; and intrinsic, confined entirely to the larynx.
The intrinsic muscles are:
Cricothyreoideus.
Cricoarytaenoideus lateralis.
Cricoarytaenoideus posterior.
Arytaenoideus.
Thyroarytaenoideus.
The Cricothyreoideus (Cricothyroid) Triangular in form, arises nfrom the front and lateral part of the cricoid cartilage; its fibers diverge, nand are arranged in two groups. The lower fibers constitute a pars obliqua nand slant backward and lateralward to the anterior border of the inferior ncornu; the anterior fibers, forming a pars recta, run upward, backward, nand lateralward to the posterior part of the lower border of the lamina of the nthyroid cartilage.
The medial borders of the two muscles are separated by a triangular ninterval, occupied by the middle cricothyroid ligament.
The Cricoarytaenoideus posterior (posterior cricoarytenoid) narises from the broad depression on the corresponding half of the nposterior surface of the lamina of the cricoid cartilage; its fibers run upward nand lateralward, and converge to be inserted into the back of the nmuscular process of the arytenoid cartilage. The uppermost fibers are nearly nhorizontal, the middle oblique, and the lowest almost vertical.
The Cricoarytaenoideus lateralis (lateral cricoarytenoid) is nsmaller than the preceding, and of an oblong form. It arises from the nupper border of the arch of the cricoid cartilage, and, passing obliquely nupward and backward, is inserted into the front of the muscular process of the narytenoid cartilage.
Side view of the larynx, showing muscular attachments.
Muscles of larynx. Side view. Right lamina of thyroid cartilage removed.
The Arytaenoideus is a single muscle, filling up the posterior nconcave surfaces of the arytenoid cartilages. It arises from the nposterior surface and lateral border of one arytenoid cartilage, and is ninserted into the corresponding parts of the opposite cartilage. It consists of noblique and transverse parts. The Arytaenoideus obliquus, the more nsuperficial, forms two fasciculi, which pass from the base of one cartilage to nthe apex of the opposite one, and therefore cross each other like the limbs of nthe letter X; a few fibers are continued around the lateral margin of the ncartilage, and are prolonged into the aryepiglottic fold; they are sometimes ndescribed as a separate muscle, the Aryepiglotticus. The Arytaenoideus ntransversus crosses transversely between the two cartilages.
The Thyreoarytaenoideus (Thyroarytenoid) is a broad, thin, muscle which lies parallel with and lateral nto the vocal fold, and supports the wall of the ventricle and its appendix. It arises nin front from the lower half of the angle of the thyroid cartilage, and nfrom the middle cricothyroid ligament. Its fibers pass backward and nlateralward, to be inserted into the base and anterior surface of the narytenoid cartilage. The lower and deeper fibers of the muscle can be ndifferentiated as a triangular band which is inserted into the vocal process of nthe arytenoid cartilage, and into the adjacent portion of its anterior surface; nit is termed the Vocalis, and lies parallel with the vocal ligament, to nwhich it is adherent.
Muscles of larynx. Posterior view.
Muscles of larynx. Side view. Right lamina of thyroid cartilage removed.
A considerable number of the fibers of the Thyreoarytaenoideus are nprolonged into the aryepiglottic fold, where some of them become lost, while nothers are continued to the margin of the epiglottis. They have received a ndistinctive name, Thyreoepiglotticus, and are sometimes described as a nseparate muscle. A few fibers extend along the wall of the ventricle from the nlateral wall of the arytenoid cartilage to the side of the epiglottis and nconstitute the Ventricularis muscle.
Actions.—In considering the actions of the nmuscles of the larynx, they may be conveniently divided into two groups, vix.: n1. Those which open and close the glottis. 2. Those which regulate the degree nof tension of the vocal folds.
The Cricoarytœnoidei posteriores separate the vocal folds, nand, consequently, open the glottis, by rotating the arytenoid cartilages noutward around a vertical axis passing through the cricoarytenoid joints; so nthat their vocal processes and the vocal folds attached to them become widely nseparated.
The Cricoarytœnoidei laterales close the glottis by rotating nthe arytenoid cartilages inward, so as to approximate their vocal processes.
The Arytœnoideus approximates the arytenoid cartilages, and nthus closes the opening of the glottis, especially at its back part.
The Cricothyreoidei produce tension and elongation of the vocal nfolds by drawing up the arch of the cricoid cartilage and tilting back the nupper border of its lamina; the distance between the vocal processes and the nangle of the thyroid is thus increased, and the folds are consequently nelongated.
The Thyreoarytœnoidei, consisting of two parts having ndifferent attachments and different directions, are rather complicated as nregards their action. Their main use is to draw the arytenoid cartilages nforward toward the thyroid, and thus shorten and relax the vocal folds. But, nowing to the connection of the deeper portion with the vocal fold, this part, nif acting separately, is supposed to modify its elasticity and tension, while nthe lateral portion rotates the arytenoid cartilage inward, and thus narrows nthe rima glottidis by bringing the two vocal folds together.
Muscles of the larynx, seen from above.
Mucous Membrane.—The mucous membrane of nthe larynx is continuous above with that lining the mouth and pharynx, and is nprolonged through the trachea and bronchi into the lungs. It lines the nposterior surface and the upper part of the anterior surface of the epiglottis, nto which it is closely adherent, and forms the aryepiglottic folds which bound nthe entrance of the larynx. It lines the whole of the cavity of the larynx; nforms, by its reduplication, the chief part of the ventricular fold, and, from nthe ventricle, is continued into the ventricular appendix. It is then reflected nover the vocal ligament, where it is thin, and very intimately adherent; covers nthe inner surface of the conus elasticus and cricoid cartilage; and is nultimately continuous with the lining membrane of the trachea. The anterior nsurface and the upper half of the posterior surface of the epiglottis, the nupper part of the aryepiglottic folds and the vocal folds are covered by nstratified squamous epithelium; all the rest of the laryngeal mucous membrane nis covered by columnar ciliated cells, but patches of stratified squamous nepithelium are found in the mucous membrane above the glottis.
Prepared nby
Reminetskyy nB.Y.
