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 in nicer-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.