Employment 5. Topographical Anatomy and Operative Surgery of Anterior and Lateral Abdominal Wall. Topographical Anatomy of Inguinal Region. Surgical Anatomy and Operative Treatment of Inguinal Herniae. Surgical Anatomy and Operative Treatment of Femoral, Umbilical Herniae and Herniae of Alba Line.
ANTERIOR ABDOMINAL WALL BOUNDARIES
The anterior abdominal wall is bounded above by the costal margins and the xiphoid process of the sternum; only the costal cartilages of ribs 7, 8, 9 and 10 take part in this boundary, for the 11th and the 12th ribs do not reach the margin. It is bounded below and on each side by the portion of the iliac crest lying between the iliac tubercle and the anterior superior iliac spine, by the inguinal ligament, the pubic crests and the upper end of the pubic symphysis. The xiphoid process lies at the bottom of the depression between the two 7th costal cartilages; its edges and
tip afford attachment for the aponeurosis of the transversus abdominis muscle. Since it is painful and at times difficult to palpate the xiphoid, the lower end of the body of the sternum serves as a preferable landmark.
SURFACE ANATOMY The lines of tension of the abdominal skin are nearly tranverse; therefore, vertical scars tend to stretch, but transverse incisions become less conspicuous with time. The skin of the abdomen is loosely attached to the underlying structures except at the umbilicus where it is normally firmly adherent. The linea alba extends in the midline from
FIG. The 9 regions of the anterolateral abdominal wall.
the xiphoid to the symphysis pubis; it is divided by the umbilicus into a supraumbilical portion, which is a band about 1/2 inch wide, and an infra-umbilical part, which is so narrow that the recti almost touch. This is important surgically, since a midline incision placed above the umbilicus comes directly onto this broad band, but in an infraumbilical midline incision it is difficult to find the threadlike midline. The linea alba is a fibrous raphe formed by the decussation of the 3 lateral abdominal muscles; since it contains few or no blood vessels, it can be incised with very little bleeding. Clinically, the anterolateral abdominal wall has been divided into 9 regions created by 2 horizontal and 2 vertical lines. The 2 horizontal lines are constructed in the following way: the upper line is placed at the level of the 9th costal cartilages, and the lower at the top of the iliac crests. The 2 vertical lines extend upward from the middle of the inguinal (Poupart’s) ligament to the cartilage of the 8th rib. The 9 regions thus constructed are: 3 upper regions—left hypochondriac, epigastric and right hypochondriac; 3 middle regions—left lumbar, umbilical and right lumbar; 3 lower regions —left iliac, hypogastric and right iliac. Identifying the regions in this way aids in the description and the location of the viscera and the abdominal masses. The umbilicus, or navel, is located in the linea alba, a little nearer the symphysis than the xiphoid. Usually its level is between the disks of the 3rd and the 4th lumbar vertebrae, but since it may vary in position, it is not too reliable a landmark. It is a puckered scar which marks the site of the umbilical cord, through which 4 tubes ,
FIG. The superficial nerve distribution of the anterolateral abdominal wall.
FIG. Side view of trunk
FIG. Distribution and attachments of Scarpa’s fascia.
FIG. The superficial veins and lymphatics of the anterolateral abdominal wall.
passed in fetal life; they are the urachus, the right and the left umbilical arteries and the left umbilical vein. They are situated in the properitoneal fat layer of the anterior abdominal wall and produce peritoneal folds. When the peritoneal aspect is studied in the adult, these 4 tubes are present as 4 atrophic fibrous cords. In the embryo, a structure called the vitello-intestinal duct is present; this connects the small bowel withthe umbilicus. If this structure is not obliterated at the time of birth, feces will discharge at the umbilicus; if the urachus is not completely obliterated at birth, urine will be noted at the same site. The hypogastric arteries of the fetus become the obliterated hypogastric arteries of the adult and pass over the lower abdominal wall as they proceed from the internal iliac arteries to the umbilicus; they may remain open and supply superior vesical branches to the urinary bladder. The umbilical vein becomes the round ligament, or ligamentum teres, of the liver. The physiologic communication between the peritoneal cavity and the umbilical cord may persist, resulting in umbilical hernias. The umbilicus may be the site for the collection and the discharge of bile and pus and may be the location of new growths such as papillomas or metastases from astrointestinal carcinomas. The well-known but infrequently seen caput medusae is located in this region and is the result of the communication between the portal and the systemic circulations when the former is impaired. The rectus abdominis muscle stands out on each side of the median line in the well-developed individual and forms a longitudinal prominence which is broader above than below; its lateral margin, which is slightly convex, is indicated by a groove on the skin known as the linea semilunaris. This line extends from the pubic tubercle to the costal margin of the 9th costal cartilage. NERVES AND SUPERFICIAL FASCIA Nerves. The skin of the anterior abdominal wall is supplied by the lower 6 thoracic and 1st lumbar nerves. The lower 6 thoracic nerves give off anterior and lateral branches, but the lateral branch of the last thoracic nerve crosses the iliac crest to supply the skin of the buttocks. The first lumbar nerve becomes the iliohypogastric nerve, which pierces the external oblique aponeurosis about
The superficial layer contains small blood vessels and nerves. This fatty connective tisse gives roundness to the body, thus preventing unsightly angularity. The deep layer of superficial fascia is quite devoid of fat and blood vessels and descends on each side in front of the inguinal ligament to blend with the fascia lata of the thigh immediately below and nearly parallel with the ligament. In the region of the pubic bone it is carried downward over the spermatic cords, the penis and the scrotum into the perineum, where it is known as Colles’ fascia. Tobin and Benjamin are of the opinion that the subcutaneous tissue is made up of only one layer and that the concept of an outer fatty and inner membranous layer is not justified.
ARTERIES, VEINS AND LYMPHATICS The superficial arteries accompany the cutaneous nerves; those which accompany the lateral cutaneous nerves are branches of the posterior intercostal arteries, while those which travel with the anterior cutaneous nerves are derived from the superior and the inferior epigastric vessels. In addition to these, 3 small branches of the femoral artery are found in the superficial fascia of the groin. They are the superficial external pudendal, the superficial epigastric and the superficial circumflex iliac arteries. The superficial veins on each side of the anterior abdominal wall are divided into 2 groups: an upper and a lower. The upper group returns the blood via the lateral thoracic and the internal mammary veins to the superior vena cava; the lower group returns its blood via the femoral vein to the inferior vena cava. Both groups anastomose freely through the thoraco-epigastric vein; the superficial veins may dilate and compensate for an obstruction of either the superior or the inferior vena cava or for an obstruction of the external or the common iliac veins. The para-umbilical veins communicate with both of these groups and constitute an important connection between the portal and the systemic venous systems. The superficial lymph vessels are divided into supra-umbilical and infra-umbilical groups. The supra-umbilical vessels drain into the pectoral lymph glands, and the infraumbilical into the superficial inguinal glands.
MUSCLES In addition to the 3 lateral flat muscles of the anterior abdominal wall (external and internal obliques and transversus abdominis), there are the recti and the pyramidalis. The 3 lateral muscles have been discussed elsewhere. Rectus Abdominis Muscle. This appears as a long, broad, muscular band, which
stretches between the pubis and the thorax on each side of the linea alba. It originates by tendinous fibers from the pubic crest and the anterior pubic ligament. As it ascends it widens and becomes thinner; it inserts on the thorax as fleshy muscular fibers. This insertion takes place along the anterior surfaces of the 5th, the 6th and the 7th costal cartilages and the xiphoid process. The insertion which is onto the front of the chest can be visualized along a horizontal line that extends from the xiphoid process to the end of the 5th rib; it is approximately 3 times as broad (
1. Above the Rib Margin. This part of the sheath is incomplete. The anterior wall is made up of the aponeurosis of the external oblique, since this is the only one of the
lateral abdominal muscles which extends above the costal margin. The posterior wall is absent and as a result of this, the rectus muscle lies directly on the cartilages.
2. From the Rib Margin Down to Mid-
way Between the Umbilicus and the Pubis. This part of the sheath is complete. The internal oblique aponeurosis divides at the lateral border of the rectus muscle into an anterior layer and a posterior layer. The anterior wall of the sheath consists of the aponeurosis of the external oblique plus the anterior layer of the aponeurosis of the internal oblique. The posterior wall consists of the posterior layer of aponeurosis of the internaloblique, the aponeurosis of the transverses abdominis and the transversalis fascia. The transversus, where it extends behind the rectus, is muscular almost to the midline. Where the posterior sheath ends, midway between the umbilicus and the pubis, an arched lower border, which is called the linea semicircularis (
ferior epigastric artery enters the sheath by crossing this edge.
3. From Midway Between the Umbilicus and the Pubis to the Pubis. The anterior wall is formed by the aponeuroses of the external and the internal obliqui and the transversus; here all the aponeuroses pass in front of the rectus. The transversus and the internal oblique are fused, but the external oblique does not fuse until it nearly reaches the midline. The posterior wall is formed by the transversalis fascia. The contents of the rectus sheath are: (1) the rectus and the pyramidalis muscles, (2) the superior and the inferior epigastric vessels, (3) the termination of the lower 5 intercostals and the 12th thoracic nerves with their accompanying vessels. The nerves enter the sheath by piercing the posterior wall near the lateral margin and then run for a short distance between the posterior sheath and the rectus before entering the muscle proper. The superior epigastric artery enters the rectus sheath behind the 7th costal cartilage and anastomoses with the inferior epigastric artery, which enters in front of the arcuate line. In this way the vessels of the upper and the lower limbs are brought into communication. Their branches are cutaneous, muscular and anastomotic. Pyramidalis Muscle. This triangular muscle lies in front of the rectus; it is frequently absent. It arises from the front of the pubis and is inserted into the lower part of the linea alba between the rectus and the anterior wall of its sheath. It is supplied by the last thoracic nerve and acts as a tensor of the linea alba.
SURGICAL CONSIDERATIONS
ABDOMINAL INCISIONS Numerous abdominal incisions have been described, but only those which are commonly used will be discussed. They may onveniently be divided in the following way.
1. Rectus
A. Paramedian
B. Pararectus
C. Transrectus (muscle-splitting)
2. Oblique
A. McBurney
B. Kocher’s subcostal
C. Iliac
FIG. Abdominal incisions. The incisions most commonly used are the rectus, the oblique, the vertical and the transverse. Examples of each are depicted in the illustration.
FIG. The pararectus incision. (A) The 11th and the 12th intercostal nerves are shown passing along the retracted lateral border of the rectus muscle. (B) Cross section, showing the lateral border of the rectus muscle retracted medially.
3. Vertical: Midline
A. Above the umbilicus
B. Below the umbilicus
4. Transverse
A. Epigastric
B. Pfannenstiel
Rectus Incisions. Incisions through the rectus sheath and muscle may be used either above or below the umbilicus. The paramedian incision is made about
A transrectus (muscle-splitting) incision is performed in the same manner as the other 2 rectus incisions but differs in that the muscle is divided longitudinally through its medial third. The medial third is chosen in order to minimize injury to the nerve fibers. The muscle is divided in the line of its fibers, the tendinous inscriptions are clamped and Iigated, and the posterior sheath and the peritoneum are incised. The incision is closed in layers.
Oblique Incisions. These have been utilized, especially in surgery on the appendix and the gallbladder. The McBurney incision is an oblique muscle-splitting incision which passes through the lateral abdominal musculature and is supposed to minimize postoperative weakness of the abdominal wall by incising the individual muscles in the direction of their fibers. The level and the length of this incision will vary according to the position of the appendix and the size of the patient. In a general way, however, it may be stated that it is made at the junction of the middle and the outer thirds and at right angles to an imaginary line joining the anterior superior iliac spine with the umbilicus. One third of the incision is placed above this line, and two thirds below it; the incision is usually about
incision may be placed on the left side for operations on the spleen or the cardiac end of the stomach. The incision is made parallel with and about
Vertical Incisions. The midline incision above the umbilicus is made directly in the linea alba, which can be located easily by the depression or pigmentation present. It begins just below the xiphoid cartilage, extends to the umbilicus and is usually 4 to
fascia are incised to the aponeurosis. The advantages of this incision are that it is almost bloodless, no muscle fibers are encountered, no nerves are injured, and it gives access to both sides of the abdomen. However, it has a disadvantage in that only one layer is available for repair because of the fusion of the aponeuroses in the midline; therefore, it cannot be relied upon and may result in weakness and herniation. The midline incision below the umbilicus is employed almost routinely in gynaecologic operations. Since the recti below the umbilicus are so close together, and because the linea alba is only a fine line, the right or the left rectus sheath is entered routinely, and the muscle is retracted laterally. Because of this, it is not exactly in the midline, and the repair is made in layers. Such a repair will result in a strong abdominal wall and does not have the disadvantage of weakness that a midline incision above the umbilicus would have.
Transverse Incisions. These abdominal incisions give excellent exposure but entail more time in execution and repair. They result iicer-looking scars and produce less injury to the nerves and the blood vessels, since they run parallel with them. The transverse epigastic incision extends from the lateral edge of one rectus to the lateral edge of the other. The underlying anterior rectus sheath, the rectus muscles, the posterior rectus sheath and the peritoneum are divided transversely on each side. If further exposure is required, the incision may be extended laterally beyond the lateral edge of the recti by splitting the oblique muscles. The individual layers of the abdominal wall are sutured separately, but it is to be recalled that only one fused layer is found in the region of the linea alba. This same incision has been modified by Sanders, who utilizes lateral retraction of the recti rather than division of these muscles. The Pfannenstiel incision is a suprapubic transverse incision which is placed at or in the upper pubic hair line and in this way becomes concealed. The skin, the subcutaneous tissue and the right and the left anterior rectus sheaths are divided transversely. The cut edges of the sheaths are dissected upward and downward for a short distance; this exposes the recti and the pyramidalis when the latter is present. The exposed recti are freed from the underlying transversalis fascia and then are retracted laterally. The transversalis fascia, the properitoneal fat and the peritoneum are incised longitudinally. In closing the wound, the layers are sutured separately in the line of their division. INCISIONAL HERNIAS Cattell has described a method which results in a 5-layer repair in which the various components of the abdominal wall are not separated at the hernial ring. It has the advantage that no dissection is carried out at a point where it is most difficult to identify the layers, and its repair results in great strength at the point of greatest potential weakness. The old scar is excised by an elliptical incision, and the sac which usually lies immediately subcutaneous is identified; this is freed down to the hernial ring. The fascia is exposed. The sac is opened, and the contents are freed carefully and reduced; frequently, resection of the omentum is necessary. The first suture line includes the hernial ring and the inner side of the peritoneum. By everting the peritoneum, a smooth peritoneal surface remains in the peritoneal cavity. The redundant part of the sac is resected, but about
INGUINAL REGION
The 9 Abdominal Layers. This region has been called the inguino-abdominal region and the inguinal trigone, the trigone being bounded by the inguinal ligament, the lateral margin of the rectus muscle and a horizontal line drawn from the anterior superior iliac spine to the rectus margin. Nine abdominal
FIG. Repair of incisional hernia. This method results in a 5-layer repair (Cattell). (A) Excision of old scar by means of an elliptical incision. (B) Identification and freeing of sac. (C) The sac has been opened, and the first suture line placed, which includes the hernial ring and the inner surface of peritoneum. All but an inch of redundant sac is removed; this constitutes suture layer Number 2. (D) and (E) show the utilization of the rectus sheath and muscle in layers 3, 4 and 5.
layers make up this region; these layers appear and are discussed in the following order:
1. Skin
2. Superficial fascia (Camper’s layer)
3. Superficial fascia (Scarpa’s layer)
4. External oblique muscle
5. Internal oblique muscle
6. Trans versus abdominis muscle
7. Transversalis fascia
8. Properitoneal fat
9. Peritoneum
The skin of this region is smooth and movable and presents 3 particular landmarks for surface anatomy. They are: the anterior superior iliac spine, which is readily palpable; the pubic tubercle, which is less easily palpated, especially in the obese; and the umbilicus.
The superficial fascia is divided into 2 layers: a superficial layer of superficial fascia and a deep layer of superficial fascia. The superficial layer is known as Camper’s fascia, and the deep layer as Scarpa’s fascia. They usually are separable below the umbilicus but are fused above this point.
FIG. The 9 layers that make up the anterolateral abdominal wall.
Camper’s fascia is the fatty layer which is continuous with the adipose tissue covering the body generally. It is also called the panniculus adiposus, its thickness depending on the amount of fat present; the cutaneous vessels and nerves run in this layer. The arteries found here are derived from the femoral artery and ascend from the thigh. They are: the superficial epigastric, which bisects the inguinal ligament and runs toward the navel; the superficial external pudendal, which runs medially across the spermatic cord and supplies the scrotum; the superficial circumflex iliac artery, which passes laterally below the inguinal ligament. Scarpa’s fascia is the membranous layer of superficial fascia; it contains no fat. The attachments of this fascia are clinically important because it is under this layer that extravasations of urine and blood take place. Scarpa’s fascia passes over the inguinal ligament and attaches to the deep fascia of the thigh (fascia lata). This attachment takes place about a finger’s breadth below and parallel with the inguinal ligament. Medially, it attaches along a line that passes with, but lateral to, the spermatic cord; this line extends from the pubic tubercle to the pubic arch. The fixation occurs lateral to the pubic tubercle. Urine, blood or an exploring finger cannot extend beyond this attachment. Medial to the tubercle, Scarpa’s fascia does not attach but continues over the penis and the scrotum; it continues as Colles’ fascia, which covers the superficial compartment of the perineum.
The external abdominal oblique muscle arises from the lower 8 ribs; its
FIG. The external abdominal oblique muscle.
fibers are directed downward, forward and medial. It interdigitates with the serratus anterior above; a continuous sheet of fascia covers both muscles. The most posterior fibers run vertically downward and insert into the anterior half of the iliac crest. Between the last ribs and the iliac crest a free border forms the lateral boundary of the lumbar (Petit’s) triangle. The muscle fibers become tendinous below the line joining the anterior superior iliac spine to the umbilicus. From the anterior superior iliac spine to the pubic spine the aponeurosis forms a free border which is called the inguinal (Poupart’s) ligament, under which vessels, nerves and muscles pass from the abdomen to the thigh.
The external oblique aponeurosis forms the inguinal, the lacunar, Cooper’s and the reflected inguinal ligaments and.
The inguinal ligament (Poupart’s) is a tendinous part of the external oblique aponeurosis which extends from the anterior superior iliac spine to the pubic tubercle. The muscles which lie below it are the iliac, the psoas major and the pectineus. The ligament folds back on itself, forming a groove; the lateral half of this is not seen because it is obscured by the origin of the internal oblique and the transversus muscles. However, the medial half forms the gutterlike floor of the inguinal canal.
The lacunar ligament (Gimbernat’s) is that part of the inguinal ligament which is reflected downward, backward and lateral. It attaches to the pectineal line, and its free crescentic margin forms the medial boundary of the femoral ring. It is the pectineal part of the inguinal ligament.
Cooper’s ligament is the lateral continuation of the lacunar ligament. It extends from the base of the lacunar ligament laterally along the pectineal line to which it is attached.
The reflected inguinal ligament (triangular ligament) consists of reflected fibers which take their origin from the inferior crus of the superficial inguinal ring and the lacunar ligament. They pass medially behind the spermatic cord and continue medially between the superior crus of the superficial inguinal ring and the conjoined tendon; they insert into the linea alba. Because of its triangular shape, this ligament has been called the triangular fascia. Arson and McVay found it unilaterally in only 3 per cent of bodies and bilaterally in less than 1 per cent.
The superficial inguinal “ring” (subcutaneous inguinal “ring,” external abdominal “ring”) has had the term “ring” applied to it, but this is unfortunate. In reality, it is a triangular thinned-out part of the aponeurosis of the external oblique muscle through which the spermatic cord in the male and the round ligament in the female pass. The apex of the triangle lies lateral to the pubic tubercle; its base, formed by the lateral half of the pubic crest, lies medial to the tubercle. The 2 sides are called the crura. The inferior crus (external pillar) is the medial end of the inguinal ligament; it attaches to the pubic tubercle. The superior crus (internal pillar) is that part of the aponeurosis which attaches to the pubic crest and the symphysis. The “ring” is not an open defect, since it is covered by the intercrural (intercolumnar) fibers which pass from one crus to the other. As the testicle made its descent, it encountered these intercrural fibers at the external “ring.” The fibers were
FIG. The ligaments in the inguinal region. (A) Poupart’s ligament and its relations to Cooper’s ligament and the lacunar ligaments. (B) The reflected inguinal ligament. The aponeurosis of the external oblique has been reflected laterally.
FIG. The superficial inguinal “ring.” The external oblique aponeurosis has been severed and retracted, but the “ring” remains intact.
pushed ahead by the descending testicle and formed a covering for the cord which is known as the external spermatic fascia.
The internal abdominal oblique muscle lies between the external oblique and the transversus abdominis muscles. This fan-shaped muscle has a narrow origin and a broad insertion. It originates from the outer half of the inguinal ligament, from the intermediate line on the iliac crest and from the posterior lamella of the lumbodorsal fascia through which it gains attachment to the lumbar spines. Because of this last fact, the muscle has no free posterior border. The uppermost fibers run almost vertically upward and are inserted into the lower 4 ribs and their cartilages. The intermediate fibers form an aponeurosis which divides above the semicircular line (of
FIG. The transversus abdominis muscle.
abandoned. In place of this the transversalis fascia is considered to be a more important structure. It is interesting to ask various surgeons to demonstrate the so-called “conjoined tendon.” Invariably, they have great trouble in identifying a true tendon and almost always point to a part of the rectus fascia in the region of the symphysis pubis. It should be emphasized that, although the fibers of the internal oblique arch over the spermatic cord, they insert behind it.
The transversus abdominis (transversalis) muscle is the deepest of the 3 lateral abdominal muscles. Only a little areolar tissue exists between it and the internal oblique muscle. It arises from the outer third of the inguinal ligament, from the inner lip of the iliac crest, from the middle layer of the lumbodorsal fascia and from the inner surface of the lower 6 costal cartilages where it interdigitates with the fleshy slips of the diaphragm. It is inserted into the linea alba and through the conjoined tendon into the pubic crest. Its aponeurosis passes behind the rectus muscle to the level of the linea semicircularis, but from this level downward it passes in front of that muscle. Most of the fibers pass in a horizontal direction; hence, its name transversus. Since the internal oblique originates from the lateral half of the inguinal ligament and the transversus abdominis originates from the lateral third of the ligament, the testicle in its descent misses the transversus fibers but comes in contact with the internal oblique fibers, dragging some of the latter downward. These form muscle loops along the spermatic cord which are known as the cremaster muscle. The action of this muscle is to draw the testicles upward. The nerves in this region are found in the interval between the internal oblique and the transversus abdominis muscles and then enter the rectus sheath. The 7th and 8th thoracic nerves pierce the posterior lamella of the internal oblique aponeurosis at the costal margin and then pass upward and medially. The 9th nerve passes medially and slightly downward. The 10th, the 11th and the 12th nerves take a more downward course as they travel medially. The last 4 nerves pierce the posterior layer of the internal oblique aponeurosis at the lateral edge of the rectus sheath, continue medially behind the rectus muscle and then pierce its substance. All these nerves supply the 3 lateral muscles as well as the rectus abdominis. They finally pass through the anterior rectus sheath and end by supplying the overlying skin. The 3 flat abdominal muscles form an elastic muscular corset which helps to maintain intra-abdominal pressure; this is of importance in retaining the viscera in place. By contracting simultaneously with the diaphragm they aid in urination, defecation, vomiting and parturition. By contracting alternately with the diaphragm (as an antagonist) they aid in exhalation. In the inguinal region these muscles form an arcade traversed by the spermatic cord. Grant has used the phrase “inguinal arcade” to describe this. When the inguinal portions of the internal oblique and transversus muscles contract, their arched fleshy fibers become straighter; this results in the lowering of the roof of the arcade and the constriction of the passage. The contraction of the external oblique approximates the anterior wall to the posterior wall, and a sphincterlike action results.
The transversaiis fascia, also called the endo-abdominal fascia, is a connective tissue layer which covers the entire internal surface of the abdomen. This fascia covers certain muscles and in each case assumes the name of the muscle which it accompanies, such as the diaphragmatic fascia, the iliac fascia, etc. Its thickness is variable, but that part which is below the inferior margins of the internal oblique and transversus abdominis muscles usually is well developed. It is in this unprotected area that it forms the floor of Hesselbach’s triangle and, when torn or weakened, predisposes to the development of a direct inguinal hernia. The fascia lies between the transversus abdominis muscle and the properitoneal fat layer. In certain areas, especially in those people where the fat layer is wanting, a fusion may result between the transversaiis fascia and the peritoneum. In a situation such as this the two layers cannot be separated, and the peritoneal cavity must be entered as if through one layer. This fascia is applied to the posterior surface of
FIG. The inguinal arcade. Grant has used this phrase to describe the muscular arcade traversed by the spermatic cord. Note the lowering of the roof of this arcade when the transversus abdominis and the internal oblique muscles contract.
the rectus sheath, and where the latter terminates at the semicircular line, it lies in direct contact with the posterior surface of the rectus muscle. Inferiorly, it is attached to the outer half of the inguinal ligament and to the iliac crest, where it becomes continuous with the iliac fascia. Over the inner half of the inguinal ligament it covers the femoral vesselsupon which it passes, behind the ligament and downward into the thigh, forming part of the anterior wall of the femoral sheath. Medial to the femoral vessels it is attached to the pectineal line and the pubic crest. Anson and Daseler have suggested that the abdominal fasciae in the adult be divided into three layers: an internal layer for the gastrointestinal tract with its vessels and nerves; an intermediate layer for the urogenital system, the adrenals and their associated vessels and nerves, together with the aorta and the vena cava; and an external layer for the parietal musculature (body wall) with its nerves and vessels. The last-mentioned outer stratum is what the majority of modern textbooks refer to as the transversaiis fascia. Tobin verified this work and states that these strata are clinically important as surgical guides and as barriers to or pathways for the spread of infection or extravasations of blood or urine.
Descent of the Testicle. The factors responsible for this descent are not understood. In the early months of intra-uterine life the scrotum is undeveloped, and the testis is located in the abdomen (lumbar region). The testicle develops between the transversalis fascia and the peritoneum in the stratum of the properitoneal fat. In the 3rd month of intra-uterine life it descends from the loin to the iliac fossa and from the 4th to the 7th months it rests at the site of the internal (abdominal) inguinal ring. During the 7th month it passes through the inguinal canal into the scrotum, preceded by a peritoneal diverticulum called the processus vaginalis; its vessels, nerves and duct are dragged after it. The gubernaculum testis is a triangular structure, the base of which is attached to the testis (epididymis), and the apex to the bottom of the scrotum. Some authors have suggested the theory that the testicle passes through the inguinal canal as a result of its being pulled into the scrotum by the contraction (or atrophy) of the musculature of the gubernaculum. Others are of the opinion that this is fallacious. Wells believes the gubernaculum to be associated with an “inguinal bursa,” thereby guiding the testis in its descent.
FIG. The descent of the testicle. (A) Early development in the lumbar region. (B) The testicle at a later stage of development in the lumbar region; it lies between the transversalis fascia and the peritoneum. The vaginal process has formed. (C) At the end of the 3rd month of intra-uterine life the testicle reaches the pelvic brim. (D) As the testicle descends in the scrotum, the vaginal process becomes differentiated into a funicular portion which is applied to the spermatic cord and a vaginal portion which is applied to the testicle. (E) The testicle has reached the base of the scrotum. Normally, the funicular portion becomes obliterated, and the vaginal portion remains patent.
FIG. Schematic drawing of the descent of the testicle. The relations between the abdominal wall, the inguinal canal, the spermatic cord and the scrotum have been stressed. As the testicle descends, it encounters certain layers of the anterior abdominal wall which it pushes ahead of it. This results in certain coverings of the spermatic cord and layers of the scrotum. The numbers indicating the layers in the scrotum and the coverings of the cord correspond to the same numbers which identify the layers of the anterior abdominal wall.
The remnants of the gubernaculum become the scrotal ligament; this is a short band which connects the inferior pole of the testicle to the bottom of the scrotum. Prior to the descent of the testicle, the vaginal process of peritoneum extends into the scrotum. This applies itself to the cord and the testicle; it forms an incomplete covering, but at no point does the processus vaginalis completely surround them. That part of the vaginal process which is applied to the testicle is the tunica vaginalis testis (vaginal portion); it remains patent. That part of the vaginal process which is applied to the spermatic cord, between the tunica vaginalis testis and the abdominal (deep) inguinal ring, becomes the funicular process; it loses its patency and becomes a fibrous cord known as the vaginal ligament. As the testicle descends, it contacts the transversalis fascia; it does not force a hole through it, but instead pushes or evaginates this fascia. In this way it acquires a tubular covering called the internal spermatic fascia (infundibuliform fascia). Therefore, the internal spermatic fascia is that evaginated portion of the transversalis fascia which supplies a covering for the spermatic cord. At that point where the testicle meets the transversalis fascia and pushes it forward, the internal inguinal ring is formed. Hence, the internal ring is a thinned-out part of the transversalis fascia. As the descent of the testicle continues, it passes below the curved border of the internal oblique muscle. It does not come in contact with the transversus abdominis muscle, since this structure lies on a higher level and therefore offers no resistance to the descent of the gland. As the testicle touches the lower border of the internal oblique muscle it drags some of its lowermost muscle fibers with it, thus forming a series of loops; in this way a second covering of the cord, the cremaster muscle, is acquired. The next layer that the gland comes in contact with is the aponeurosis of the external abdominal oblique muscle; it arrives at this point at the 8th month. It evaginates this aponeurosis and acquires another covering of the spermatic cord called the external spermatic fascia. Thus the testis and the cord have acquired 3 coverings: (1) the internal spermatic fascia from the transversalis fascia, (2) the cremaster muscle from the internal oblique and (3) the external spermatic fascia from the aponeurosis of the external abdominal oblique aponeurosis. The so-called “rings” are not true rings or defects. The internal “ring” is a thinned-out portion of transversalis fascia, and the external “ring” is a thinned-out portion of the aponeurosis of the external abdominal oblique aponeurosis. The testicle pushes Scarpa’s fascia ahead of it; it becomes the Colles’ fascia of the perineum. Camper’s fascia (panniculus adiposus) is a fatty layer and, since there is no fat in the scrotum, it is replaced by the dartos muscle. At the 9th month the testicle reaches the scrotum.
The Inguinal Canal. The fully developed inguinal canal is not a canal in the true sense of the word but is a cleft which takes an oblique course through the inguinoabdominal region. In the adult its length is about 4 to
FIG. The formation of the external spermatic fascia, cremaster muscle and the internal spermatic fascia.
ligament and the transversalis fascia. The cord rests on this groove.
Types of Indirect Inguinal Hernias. Soon after birth, the processus vaginalis, a peritoneal diverticulum, becomes occluded at two points. First, at the internal abdominal ring and, second, directly above the testis. That part of the vaginal process which is situated between these two points, the funicular process, becomes obliterated. If the vaginal process remains patent throughout its entire course and the opening above is wide enough, bowel or omentum may enter this process and pass into the scrotum. This condition is known as a vaginal (congenital) indirect inguinal hernia. When only the proximal or funicular portion of the vaginal process remains open, a funicular indirect hernia results. An encysted hernia is the same as a vaginal type plus a process of peritoneum which lies in front of the sac and extends up to the external ring. This is due to the catching of a diverticulum of the processus vaginalis at the external ring during development. In the infantile type, the conditions are exactly the same as are found in the funicular type, plus a process of peritoneum which is found in front of the hernia as high as the external ring. Therefore, at operation a peritoneal sac is found in front of the hernial sac; this may be very confusing unless they are identified properly. The interstitial types of hernias are due to a diverticulum of the processus vaginalis which becomes caught between the layers of the developing abdominal wall. These types of hernias are rare and usually are found associated with imperfectly descended testicles. The sac may be:
FIG. Types of indirect inguinal hernias.
1. Proparietal (extraparietal), between the superficial fascia and the external oblique muscle.
2. Interparietal (intramuscular), between the internal and the external oblique muscles.
3. Retroparietal (intraparietal) between the transversalis fascia and the peritoneum.
Types of Hydroceles. In the true hydrocele there is a collection of fluid in some part of the processus vaginalis; the types may be vaginal, congenital, infantile and hydroceles of the cord. The vaginal type presents a collection of fluid, not due to any fault of development, in the tunica vaginalis. Since it is acquired, it becomes important to determine whether it is the so-called common “idiopathic” variety or secondary to some disease of the testis or the epididymis, such as a malignancy or tuberculosis. The congenital type is also known as an intermittent hydrocele; it is due to a tiny communication between the processus vaginalis and the peritoneal cavity which permits the escape of fluid. It may be confused with a congenital hernia. In the infantile type, the processus vaginalis is occluded only at the internal abdominal ring. In hydrocele of the cord, the funicular process fails to shrink to a fibrous cord so that a tubular cavity results. This is shut off
FIG. Types of hydroceles.
from the peritoneum above and the tunica vaginalis below. As it becomes distended with fluid it forms one or more swellings which are separated from the testicle.
SURGICAL CONSIDERATIONS
INGUINAL HERNIAS, INDIRECT AND DIRECT
Indirect Hernias. Many methods exist for the repair of an indirect inguinal hernia. An exhaustive and exhausting literature is accessible to any one interested in special studies of this problem. However, in considering herniorrhaphies, certain points should be stressed, such as the modern concept of the conjoined tendon (doubting the existence of such a structure), the importance of the transversalis fascia, and the management of the sac. A method which emphasizes these points will be described. The incision is made from a point which joins the middle and the outer thirds of a line between the anterior superior iliac spine and the umbilicus to a point which marks the pubic tubercle. It is difficult actually to feel this tubercle, since the spermatic cord passes over it; hence, the pubic bulge which is produced by the spermatic cord is the landmark used. The incision is deepened through Camper’s and Scarpa’s fascia until the aponeurosis of the external abdominal oblique is exposed. The external inguinal ring is identified, and the continuation of the external abdominal oblique over this ring, namely, the external spermatic fascia, is incised. Then the external oblique aponeurosis is incised, and its edges are held apart and dissected free from the underlying internal oblique muscle. The iliohypogastric and the ilio-inguinal nerves usually can be demonstrated at this point. The lower border of the internal oblique becomes visible, and its continuation, the cremaster muscle loops, should be elevated. These are severed, and the internal oblique is freed from the underlying transversalis fascia. The transversus abdominis muscle is not seen because it is not situated this low. A small blunt retractor is placed under the dissected free edge of the internal oblique, and this muscle is retracted cephalad. The lateral cut edge of the external oblique aponeurosis is retracted outward, thus exposing Poupart’s ligament. The finger or a blunt instrument is placed on this ligament and passed downward to the pubic spine. This elevates the spermatic cord, which then is retracted laterally. Since the hernial sac is found at the upper inner quadrant of the cord, lateral traction on the cord tenses the transversalis fascia which overlies the sac. It is at this quadrant that the transversalis fascia should be opened. Then the properitoneal fat layer is identified; it serves as an excellent guide, since the peritoneum (sac) lies immediately subjacent to this fat. However, the transversalis fascia, the properitoneal fat and the peritoneum may be fused into one layer, especially in thin
individuals, so that the sac is entered immediately when an attempt is made to dissect the transversalis fascia.
The sac is dissected free from the surrounding structures, it is opened, and its contents are reduced. Its neck should be freed as high as possible, which anatomically implies on a level with the deep epigastric vessels. In indirect inguinal hernias these vessels lie medial to the neck of the sac. With downward traction on the sac and upward traction on the internal oblique and the transversalis fascia, a high ligation becomes possible. The sac is transfixed and ligated, and the redundant tissue distal to the ligature is cut away. The defect in the transversalis fascia, which the surgeon has created, must be repaired properly to prevent the development of a direct hernia. This closure is accomplished by means of a purse-string suture which incorporates the fascia overlying the spermatic cord. Then the free edge of transversalis fascia is sutured to Poupart’s ligament. No sutures are placed in the internal oblique muscle, since this would interfere with its sphincteric or shutterlike action. The cut edges of the aponeurosis of the external abdominal oblique are sutured, thus reconstructing the roof of the inguinal canal. Scarpa’s fascia and the skin are closed as separate layers. Direct Hernias. Since the underlying cause of a direct inguinal hernia is a weakness of or defect in the transversalis fascia, the method of repair becomes the most important feature. The operation is essentially the same as that described for an indirect hernia. When the bulge of a direct hernia has been located, the thinned transversalis fascia is opened and the underlying properitoneal fat and the hernial sac are freed. The sac usually is not opened but is reduced by means of a purse-string suture. One attempts to repair the defect in the thin transversalis fascia by means of mattress sutures which imbricate it. The resulting free edge of trans-
Fig. Embryology of the umbilical region. The cloaca, a part of the hindgut, separates into a dorsal part (rectum) and a ventral part. The ventral part divides into a cranial part (the urachus), a middle part (the bladder) and a caudal part (the urethra).
versalis fascia then is sutured to Poupart’s ligament. If the fascia is too thin and will not hold the sutures, a flap of the anterior rectus sheath (internal oblique aponeurosis) is freed and sewed to Poupart’s ligament. Numerous modifications, including cutis grafts, wire mesh and fascia lata have been used to strengthen this defect.
Embryology. The cloaca is a part of the hindgut which ultimately separates into a dorsal part (rectum) and a ventral part. The ventral section divides into 3 components: (1) a cranial component which becomes the urachus (allantois), (2) a middle part which becomes the bladder and (3) a caudal part which becomes the urethra and, in the female, part of the vagina. The upper part of the allantois is continued into the umbilicus and the umbilical cord; the intraabdominal portion of the allantois is called the urachus. The urachus and the allantois become a solid cord, which may develop cystlike dilatations. These dilatations are characteristic of this cord and may be found at any period in the development of the embryo. They persist in many adults and account for the small cysts found at operation. If the urachus remains patent at birth, a urinary umbilical fistula results. If the peritoneal surface of the umbilical region is examined, 4 fibrous cords are seen radiating from it. These are the remains of 4 tubes which pass through the umbilical cord in fetal life; they are the urachus, the right and the left umbilical arteries and the left umbilical vein. They are situated in the extraperitoneal fatty layer of the anterior abdominal wall and produce peritoneal folds. In the early human embryo the alimentary tract communicates with the yolk sac by means of a vitello-intestinal (omphalomesenteric) duct. This structure usually disappears when the embryo is between 6 and
region pass in the subcutaneous fat and drain in 4 directions. The upper set passes to the axillary lymph glands, and the lower ones to the superficial inguinal group. These channels dip a little deeper and may rest on the muscular aponeurosis. Those from the upper umbilical region pass to either side of the falciform ligament of the liver, pierce the diaphragm and drain into the anterior mediastinal glands. Small lymph channels are found along the course of the round ligament of the liver; along this channel carcinoma of
FIG. The umbilicus. (A) Tn the fetus, 4 structures radiate from the umbilicus: the umbilical vein above and the 2 umbilical arteries and the urachus below. (B) The umbilicus seen from within, in the adult. The obliterated umbilical vein becomes the round ligament of the liver. The urachus becomes the median umbilical ligament, and the 2 obliterated
umbilical arteries become the lateral umbilical ligaments. the gastrointestinal tract (stomach and gallbladder) reaches the telltale umbilical lymph node. The lateral channels at first pass laterally, then curve downward to reach the deep inguinal glands. Thus, the lymph channels from the lower portion of the umbilicus may pass directly downward to the deep inguinal set. Therefore, it is possible to find carcinomatous metastases at the umbilicus; a primary malignant tumor from the ovaries and the adnexae spreads by means of the lower set, and carcinoma from the gastrointestinal tract from the upper set. Types of Umbilical Hernias. Hernias may occur in this region, and, owing to the persistence of the embryologic communication between the peritoneal cavity and the umbilical cord, a congenital umbilical hernia may develop. Umbilical hernias have been classified as follows: (1) hernia of the umbilical cord, (2) umbilical hernia in adults and (3) umbilical hernia in children. Hernias of the umbilical cord may contain a considerable portion of the abdominal viscera. The coverings of such a hernia are amnion, Wharton’s jelly and peritoneum. These coverings are so thin that the hernial contents may be seen through these diaphanous coverings. There is no skin over such a protrusion except at its edges. The condition has also been referred to as exomphalos and may be subdivided into complete or partial. The umbilical hernia of adults is the acquired umbilical hernia. The umbilical cicatrix becomes greatly stretched, allowing a process of peritoneum with coils of gut or omentum to escape through it. It is usually large and requires surgical repair. It should be recalled that the fibers of the rectus sheath run transversely; hence, Mayo has devised a procedure in which the incision follows the course of these transverse fibers. The congenital hernia of children usually is due to one of two causes, namely, the persistence of a small peritoneal process into the umbilical cord or an imperfect closure in the linea alba immediately above the umbilicus. Straining at stool and coughing may be additional predisposing factors.
REPAIR OF UMBILICAL HERNIAS An umbilical hernia rarely protrudes directly through the umbilical ring, but rather appears above or below it. A wide, elliptical, transverse incision is made, including the umbilicus at its central point. The incision is deepened to the rectus sheaths, and the neck of the sac is defined and freed from all adjacent tissues. Horizontal incisions are made at each end of the rectus sheaths; these enlarge the neck of the sac and aid in the reduction of its contents. The sac is opened at its neck; the contents are freed and returned to the peritoneal cavity. Some surgeons prefer to close the peritoneum as a separate layer but since this is usually very difficult to define, because of the great amount of scarring, a repair is effected which includes fascia, scar and peritoneum together. The repair is made by imbricating the upper flap over the lower with interrupted mattress sutures. This is followed by interrupted sutures placed between the free margin of the overlapping sheath and the lower flap. line erected at the anterior superior iliac spine. The superficial fascia is arranged in two layers between which a large amount of fat usually is deposited. To understand the arrangement of the musculature in this region, reference should be made to the lumbodorsal (lumbar) fascia.
