ments of the trunk during normal sitting and standing; these move- Attachments Rectus abdominis arises by two tendons. The larger,
ments are controlled predominantly by the paravertebral and spinal lateral tendon is attached to the pubic crest and may extend beyond the
muscles. However, movements of the trunk against resistance or when pubic tubercle to the pectineal line. The medial tendon interlaces with
the individual is supine require the anterolateral abdominal muscles. the contralateral muscle and blends with ligamentous fibres covering
Rectus abdominis is the most important in these situations, producing the front of the pubic symphysis. Additional fibres may arise from the
anterior flexion of the trunk. If the pelvic girdle is fixed, flexion of the lower part of the linea alba. The pubic attachment of the tendon of
thoracic girdle occurs. With a fixed thoracic cage, contraction of rectus rectus abdominis and its anterior sheath run over the anterior surface
abdominis causes the pelvis to tilt and lift. Lateral flexion and rotation of the pubic symphysis and become continuous with the attachments
of the trunk against resistance is provided by unilateral contraction of of gracilis and adductor longus (Norton-Old et al 2013). Superiorly,
the oblique muscles. rectus abdominis is attached by three slips of muscle to the fifth, sixth
and seventh costal cartilages. The most lateral fibres are usually attached
Rectus abdominis
to the anterior end of the fifth rib; occasionally, this slip is absent or it
Rectus abdominis is a paired, long, strap-like muscle that extends along extends to the fourth and third ribs. The most medial fibres are occa-
the entire length of the anterior abdominal wall on either side of the sionally connected to the costoxiphoid ligaments and the side of the
linea alba (Fig. 61.6). It is widest in the upper abdomen. The muscle xiphoid process.
fibres of rectus abdominis are partially interrupted by three fibrous
bands or tendinous intersections, which pass transversely or obliquely Vascular supply Rectus abdominis is supplied principally by the


across the muscle. One is usually situated at the level of the umbilicus, superior and inferior epigastric arteries, the latter being the dominant
another opposite the free end of the xiphoid process and a third about supply. Small terminal branches from the lower three posterior inter-
midway between the other two. They are rarely full-thickness and costal arteries, the subcostal artery, the lumbar arteries and the deep
usually extend only half-way through the anterior thickness of the circumflex iliac artery may contribute, particularly at the lateral edges


Anterior AbdominAl wAll
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Fig. 61.5 The cutaneous branches of
the lower intercostal and lumbar
Serratus anterior
nerves. Portions of the muscles of
the anterior abdominal wall have
been removed, including most of the
Latissimus dorsi anterior layer of the rectus sheath
and parts of rectus abdominis.
Sixth intercostal nerve Lateral cutaneous branches
of intercostal nerve
Innermost intercostal
Lateral cutaneous branches
Tenth intercostal nerve
Rectus abdominis (cut)
External oblique (cut)
Transversus abdominis
Eleventh intercostal nerve
Anterior cutaneous branch
Subcostal nerve
Arcuate line Iliohypogastric nerve
Ilioinguinal nerve
Transversalis fascia
Rectus abdominis (cut) Internal oblique (cut)
Anterior lamina of Inguinal ligament
rectus sheath
Spermatic cord
and the lower parts of the muscle, where they anastomose with small from all three anterior leaves run obliquely upwards, whereas the pos-
lateral branches of the epigastric arteries. Rectus abdominis provides a terior leaves run obliquely downwards at right angles to the anterior
reliable and versatile myocutaneous flap, either pedicled or free, because leaves. Above the arcuate line, the anterior rectus sheath is composed
of the excellent vascularity provided by the epigastric vessels and of both leaves of the aponeurosis of external oblique and the anterior
because the muscle belly can be separated relatively easily from its leaf of the aponeurosis of internal oblique fused together. The poste-
surrounding sheath. The upper half of the muscle may be used for rior rectus sheath is composed of the posterior leaf of the aponeurosis
breast reconstruction, and the lower half may be transposed to the of internal oblique and both leaves of the aponeurosis of transversus
groin and upper thigh or rotated on its lower attachments and delivered abdominis. Thus, both the anterior and posterior layers of the rectus
into the perineum for reconstruction after radical pelvic and perineal sheath consist of three layers of fibres with the middle layer running


resections. at right angles to the other two. At the midline, the anterior and pos-
terior layers are closely approximated. Fibres from each layer decussate
Innervation Rectus abdominis is innervated segmentally by the ter- to the opposite side of the sheath, forming a continuous aponeurosis
minal branches of the ventral rami of the lower six or seven thoracic with the contralateral muscles. Fibres also decussate anteroposteriorly,
spinal nerves. It may also receive a branch from the ilioinguinal nerve crossing from the anterior sheath to the posterior sheath. The dense
(Rozen et al 2008). fibrous line caused by this decussation is called the linea alba. The
external oblique, internal oblique and transversus abdominis muscles
Actions The recti contribute to flexion of the trunk and the mainte- can therefore be regarded as digastric muscles with a central tendon
nance of abdominal wall tone required during straining. comprising the linea alba (Rizk 1980). The decussating fibres at the
linea alba can be used to identify the midline during surgical incisions.
rectus sheath Below the arcuate line, all three aponeuroses from the oblique and
Rectus abdominis on each side is enclosed by a fibrous sheath (Figs transversus abdominis muscles pass into the anterior rectus sheath (see
61.7–61.10). The anterior portion of this sheath extends the entire Fig. 61.7).
length of the muscle and fuses with periosteum and ligaments at sites
of the muscle’s attachments. The posterior part of the sheath is complete linea alba and umbilicus
behind the upper two-thirds of the muscle but absent below this level, The linea alba is a tendinous raphe extending from the xiphoid process
which corresponds to approximately one-third of the distance between to the pubic symphysis and pubic crest. It lies between the two recti and
the umbilicus and the pubis (Loukas et al 2008). The termination of is formed by the interlacing and decussating aponeurotic fibres of exter-
the posterior rectus sheath is usually gradual but may be abrupt and nal oblique, internal oblique and transversus abdominis. At its lower


marked by a clearly visible curved horizontal line known as the arcuate end, the linea alba has two attachments to the pubis: superficial fibres
line (of Douglas). Below this level, rectus abdominis lies on the trans- are attached to the pubic symphysis, and deeper fibres form a triangular
versalis fascia and extraperitoneal connective tissue. lamella that is attached behind rectus abdominis to the posterior
The rectus sheath is formed from the aponeuroses of all three surface of both pubic crests (adminiculum lineae albae). The fundiform
lateral abdominal muscles: namely, external oblique, internal oblique ligament of the penis and pyramidalis are attached to the suprapubic
and transversus abdominis. Each aponeurosis is bilaminar; the fibres part of the linea alba. The linea alba is visible externally in those who


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muscles
Fig. 61.6 Muscles of the left side of
the trunk. External oblique has been
Pectoralis major (cut) removed to show internal oblique,
but its digitations from the ribs have
been preserved. The sheath of rectus
abdominis has been opened and its
anterior layer removed.
Latissimus dorsi
Linea alba
Digitations of external oblique
Internal intercostal muscle of
tenth intercostal space
Tendinous intersections
Internal oblique
Aponeurosis of internal oblique
Rectus abdominis
Cut edge of aponeurosis
of external oblique
Anterior superior iliac spine
Gluteus medius
Inguinal ligament
Gluteus maximus
Pyramidalis
Spermatic cord
Tensor fasciae latae
Sartorius Rectus femoris
A Rectus abdominis Linea alba External oblique Fig. 61.7 Transverse
sections through the
anterior abdominal wall.
A, Immediately above the
umbilicus. B, Below the
arcuate line. The bilaminar
nature of each muscular
aponeurosis is difficult to
illustrate in cross-section.
Peritoneum Transversalis fascia Internal oblique The fibres appear to fuse
into a single sheet during
Preperitoneal fat Transversus abdominis
formation of the rectus
B Rectus abdominis Linea alba External oblique sheath. Note that rectus is
supported directly by the
transversalis fascia below
the arcuate line.
Peritoneum Transversalis fascia Internal oblique
Preperitoneal fat Transversus abdominis
are lean and muscular, as a shallow midline groove in the anterior consists of skin, a fibrous layer (representing the area of fusion between
abdominal wall. Its width varies along its length: it is wider above the the round ligament of the liver, the median umbilical ligament, and
umbilicus than below, and widest at the level of the umbilicus (Rath two medial umbilical ligaments), the transversalis fascia, the umbilical
et al 1996). It is wider and thinner in women, in adults aged over fascia surrounding the urachal remnant, and peritoneum (Fathi et al


50 years, and in the obese and multiparous (Naraynsingh et al 2012). 2012). Its appearance and position are variable (Fathi et al 2012). In
Its tensile strength is proportional to its thickness and density (Kore- adults, it tends to lie at a relatively lower position with advancing age,
nkov et al 2001). The linea alba is relatively bloodless but it is crossed in men, and in individuals with a higher body mass index.
superficially from side to side by a few small blood vessels. In the fetus, the umbilicus transmits the umbilical vessels, urachus
The umbilicus is a fibrous cicatrix that lies a little below the mid- and, up to the third month of gestation, the vitelline or yolk stalk. It
point of the linea alba, and is covered by an adherent area of skin. It closes a few days after birth, but the vestiges of the vessels and urachus


Anterior AbdominAl wAll
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A A
B Fused aponeuroses B Aponeurosis
of external and of external oblique
internal oblique
Linea alba Linea alba Aponeurosis of
External oblique
transversus
Rectus abdominis Internal oblique Rectus abdominis abdominis
Internal oblique
Transversus
Fused aponeuroses
of internal oblique and abdominis Transversalis Transversus
transversus abdominis fascia abdominis
Left renal vein
Aorta
Fig. 61.8 The rectus sheath. Computed tomography scan (A) and Fig. 61.9 The rectus sheath. Computed tomography scan (A) and
diagram (B) of the anterior abdominal wall, demonstrating the formation of diagram (B) of the anterior abdominal wall, demonstrating the formation of
the rectus sheath above the umbilicus. The anterior rectus sheath is the rectus sheath below the umbilicus. The posterior rectus sheath is
composed of both leaves of the aponeurosis of external oblique and the replaced by the transversalis fascia and extraperitoneal connective tissue.
anterior leaf of the aponeurosis of internal oblique, fused together.
The posterior rectus sheath is composed of the posterior leaf of the
aponeurosis of internal oblique and both leaves of the aponeurosis of
transversus abdominis.
Posterior rectus sheath Fig. 61.10 The concept of bilaminar aponeuroses of the
oblique and transversus abdominis muscles. Note that
Laminae of Posterior lamina of the fibres of the superficial and deep laminae are
transversus abdominis internal oblique approximately at right angles; decussations occur as part
Posterior Anterior of the linea alba.
Transversus abdominis
Internal oblique
Rectus
abdominis External oblique
Anterior lamina of Posterior Anterior
internal oblique
Laminae of
external oblique
Anterior rectus sheath


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muscles
remain attached to its deep surface. The remnant of the embryonic left siderably in size. It may be larger on one side than on the other, some-
umbilical vein forms the round ligament of the liver. The obliterated times absent on one or both sides, or rarely doubled.
umbilical arteries form the medial umbilical ligaments on the under-
surface of the anterior abdominal wall and are covered by the medial Vascular supply Pyramidalis is supplied by branches of the inferior
umbilical folds. The partially obliterated remains of the urachus persist epigastric artery. A small artery frequently crosses the midline posterior
as the median umbilical ligament and fold. Both congenital and to the belly of the muscle to anastomose with the contralateral vessel.
acquired umbilical hernias are common; most childhood umbilical
hernias close spontaneously and do not require surgical repair. The Innervation Pyramidalis is usually supplied by the terminal branches
umbilicus is the most common site for laparoscopic access to the peri- of the subcostal nerve, the ventral ramus of T12, but it may be inner-
toneal cavity. vated wholly or in part by fibres from L1 travelling in the subcostal or
ilioinguinal nerves (Tokita 2006).
divarication of the recti
Actions Pyramidalis contributes to tensing the lower linea alba but
Thinning and widening of the linea alba in the upper abdomen may
is of doubtful physiological significance.
occur, most commonly as a result of pregnancy, obesity or chronic
straining (Akram and Matzen 2014). Abdominal viscera protrude
beneath the thinned tissue as a broad midline bulge, particularly when External oblique
intra-abdominal pressure is raised, and the recti become widely sepa- Attachments External oblique is the largest and most superficial of
rated or divaricated. This state is not true herniation because all the
the three anterolateral abdominal muscles (Fig. 61.11). It curves around
layers of the abdominal wall in the region are intact.
the lateral and anterior parts of the abdomen and is attached to the
external surfaces and inferior borders of the lower eight ribs. The attach-
Pyramidalis
ments rapidly become muscular and interdigitate with the lower fibres


Attachments Pyramidalis is a triangular muscle that lies in front of of serratus anterior and latissimus dorsi along an oblique line that
the lower part of rectus abdominis within the rectus sheath. It is attached extends downwards and backwards. The upper attachments are close to
by tendinous fibres to the anterosuperior margin of the pubis and to the cartilages of the corresponding ribs, the middle ones arise from the
ligamentous fibres in front of the symphysis. The muscle diminishes in ribs at some distance from their cartilages, and the lowest are close to
size as it runs upwards, and ends in a pointed apex that is attached the apex of the cartilage of the twelfth rib. The fibres of external oblique
medially to the linea alba. This attachment often lies midway between diverge as they pass to their lower attachments. Those from the lower
the umbilicus and pubis, but may occur higher. The muscle varies con- two ribs pass nearly vertically downwards and attach to the anterior half
Fig. 61.11 The left anterolateral
abdominal wall muscles.
Pectoralis major
Serratus anterior
Latissimus dorsi
Linea alba
Rectus sheath, anterior layer
External oblique
Tendinous intersections
Linea semilunaris
External oblique aponeurosis Lumbar triangle
Crest of ilium
Anterior superior iliac spine
Gluteus medius
Inguinal ligament
Gluteus maximus
Superficial inguinal ring
Spermatic cord
Tensor fasciae latae
Femoral fascia


Anterior AbdominAl wAll
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or more of the outer lip of the iliac crest. The middle and upper fibres Innervation Internal oblique is innervated by the terminal branches
pass downwards and forwards, and end in the anterior aponeurosis, of the lower five intercostal nerves and the subcostal nerve from the
whose fibres cross the midline (see above). The junction between ventral rami of the lower six thoracic spinal nerves. In addition, it
muscle and aponeurosis extends along a vertical line from the ninth receives a small contribution from the iliohypogastric and ilioinguinal
costal cartilage to just below the level of the umbilicus; muscle fibres nerves derived from the ventral ramus of the first lumbar spinal nerve.
do not usually descend beyond a line from the anterior superior iliac
spine to the umbilicus. External oblique has a free posterior border. Actions Internal oblique contributes to the maintenance of abdomi-
The inguinal ligament is formed by the inferior margin of the nal tone, increasing intra-abdominal pressure, and lateral flexion of the
aponeu rosis of external oblique extending between the anterior supe- trunk against resistance.
rior iliac spine and the pubic tubercle. The fibres of the aponeurosis of
Transversus abdominis
external oblique are not parallel to the long axis of the inguinal liga-
ment; they approach the ligament obliquely at an angle of 10–20° and Attachments Transversus abdominis is the deepest of the anterola-
then turn medially to run along the ligament to reach the pubic tubercle teral abdominal muscles (Fig. 61.12). It is attached to the iliopectineal
(Lytle 1974). The deepest fibres of the aponeurosis spread out postero- arch deep to the lateral third of the inguinal ligament, the anterior two-
medially to insert into the pectineal line. thirds of the inner lip of the anterior segment of the iliac crest, the
The upper and lower rib attachments of the muscle may be absent. thoracolumbar fascia between the iliac crest and the twelfth rib, and the


Digitations or even the entire muscle may be duplicated. The upper internal aspects of the lower six costal cartilages. The costal attachments
attachments of the muscle are sometimes continuous with pectoralis interdigitate with those of the diaphragm. The muscle ends anteriorly
major or serratus anterior. in an aponeurosis; the lower fibres of the aponeurosis curve downwards
and medially, together with those of the aponeurosis of internal oblique,
Vascular supply External oblique is mainly supplied by branches and insert into the pubic crest and pectineal line to form the conjoint
from the lower posterior intercostal and subcostal arteries above and tendon. A few muscle fibres may run from the lower border of trans-
the deep circumflex iliac artery below. There are additional smaller versus abdominis to the inguinal ligament and reinforce the interfoveo-
contributions (Schlenz et al 1999). lar ligament (see above). The remainder of the aponeurosis passes
medially and the fibres decussate at, and blend with, the linea alba. The
Innervation External oblique is innervated by the terminal branches upper costal and anterior iliac fibres of transversus abdominis are short
of the lower five intercostal nerves and the subcostal nerve from the and the thoracolumbar fibres are the longest. Near the xiphoid process,
ventral rami of the lower six thoracic spinal nerves. the aponeurosis is formed only a few centimetres from the linea alba
and so the muscular part of transversus abdominis extends behind
Actions External oblique contributes to the maintenance of abdomi- rectus abdominis into the posterior layer of the rectus sheath. The
nal tone, increasing intra-abdominal pressure, and lateral flexion of the medial edge of the muscle, at the origin of the aponeurosis, curves
trunk against resistance. downwards and laterally, and is furthest from the lateral edge of the
rectus sheath at the level of the umbilicus. It then curves downwards
inguinal ligament and medially towards the superficial inguinal ring.
The inguinal ligament is the thick lower border of the aponeurosis of Occasional defects may occur in the lower muscular and aponeurotic


external oblique that stretches between the anterior superior iliac spine parts of both internal oblique and transversus abdominis. The two
and the pubic tubercle. Its medial half is curled in on itself, forming muscles are sometimes fused and, rarely, transversus abdominis may be
the gutter-like ‘floor’ of the inguinal canal. The ligament is not exactly absent.
linear but has an inferior and an anterior convexity. At its lower border,
it is fused with the fascia lata. Laterally, it is fused with the iliopsoas Vascular supply Transversus abdominis is supplied by branches
fascia (Lytle 1974). At the medial end of the inguinal ligament, near from the lower posterior intercostal and subcostal arteries, the superior
its site of attachment to the pubic tubercle, some of its fibres extend and inferior epigastric arteries, the superficial and deep circumflex iliac
posteriorly and laterally to attach to the pectineal line, forming the arteries and the posterior lumbar arteries.
triangular, shelf-like lacunar ligament. Other fibres pass upwards and
medially behind the superficial inguinal ring and external oblique Innervation Transversus abdominis is innervated by the terminal
aponeurosis to join the rectus sheath and linea alba; these constitute branches of the lower five intercostal nerves, the subcostal nerve and
the reflected part of the inguinal ligament (Tubbs et al 2009). Fibres the iliohypogastric and ilioinguinal nerves. These arise from the ventral
from both sides decussate in the linea alba. rami of the lower six thoracic and first lumbar spinal nerves.
Internal oblique Actions Transversus abdominis contributes mainly to the mainte-
Attachments Internal oblique lies deep to external oblique for most nance of abdominal tone and increasing intra-abdominal pressure.
of its course (see Fig. 61.6). It is thinner and less bulky than external
Conjoint tendon
oblique. Its fibres are traditionally stated to arise from the lateral two-
thirds of the inguinal ligament but, in fact, arise from the corresponding The conjoint tendon is formed from the lower fibres of internal oblique


length of a slightly deeper structure known as the iliopectineal arch and the lower part of the aponeurosis of transversus abdominis. It is
(Acland 2008), a thickened band of iliopsoas fascia that passes down- attached to the pubic crest and extends to a variable extent along the
wards and medially from the anterior superior iliac spine to the ilio- pectineal line (see Fig. 61.16). It descends behind the superficial
pectineal eminence of the hip bone. Further laterally, internal oblique inguinal ring and acts to strengthen the medial portion of the posterior
is attached to the anterior two-thirds of the iliac crest deep to the attach- wall of the inguinal canal. Medially, the upper fibres of the tendon fuse
ment of external oblique. Posteriorly, some fibres are attached to the with the anterior wall of the rectus sheath, and laterally, some fibres
thoracolumbar fascia. The fibres originating from the posterior end of may blend with the interfoveolar ligament.
the iliac attachment pass obliquely upwards and are attached to the Cremaster
inferior borders and tips of the lower three or four ribs and their carti-
Attachments Cremaster consists of loosely arranged muscle fasciculi
lages. Here, the attachments merge with those of the internal intercostal
lying along the spermatic cord or round ligament of the uterus. It is
muscles. The uppermost fibres form a short, free superior border. The
variable in thickness but thickest in young men. Together with connec-
fibres from the anterior end of the iliac crest diverge and end in the
tive tissue, it forms an incomplete coating around the spermatic cord,
anterior aponeurosis, which gradually broadens from below upwards.
known as the cremasteric fascia, which extends down around the testis
The uppermost part of the aponeurosis is attached to the cartilages
deep to the external spermatic fascia. The muscle consists of a lateral
of the seventh, eighth and ninth ribs. The fibres that originate adjacent
part that arises mainly from the inferomedial border of internal oblique
to the inguinal ligament arch downwards and medially across the sper-
and transversus abdominis but also has attachments to the middle of


matic cord in the male and the round ligament of the uterus in the
the inguinal ligament, and a medial part attached to the pubic tubercle,
female. They become tendinous, fuse with the corresponding part of
lateral pubic crest and the lower border of transversus abdominis;
the aponeurosis of transversus abdominis, and attach to the pubic crest
this part is variably developed, and may be absent (Shafik 1977). The
and medial part of the pectineal line, forming the conjoint tendon.
longitudinal muscle fibres spread out over the spermatic cord as it
approaches the superficial inguinal ring. Cremaster is composed of both
Vascular supply Internal oblique is mainly supplied by branches
striated and smooth muscle fibre bundles (Kayalioglu et al 2008).
from the lower posterior intercostal and subcostal arteries, the inferior
epigastric artery, and the deep circumflex iliac artery. There are several Vascular supply Cremaster is supplied by the cremasteric artery, a
smaller contributions (Yang et al 2003). branch of the inferior epigastric artery.


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muscles
Fig. 61.12 The left transversus
abdominis. The aponeurosis of
transversus abdominis fuses into
the posterior layer of the rectus
Serratus anterior sheath above the arcuate line. The
position of the lateral border of
Latissimus dorsi rectus abdominis is shown by the
dotted white line.
Cut edge of posterior lamina of
aponeurosis of internal oblique
Posterior lamina of sheath Thoracolumbar fascia
of rectus abdominis
Transversus abdominis
Cut edge of aponeurosis of
internal oblique
Arcuate line
Cut edge of internal oblique
Transversalis fascia
Cut edge of aponeurosis
Rectus abdominis (cut) of external oblique
Anterior superior iliac spine
Cut edge of aponeurosis
of external oblique
Inguinal ligament
Transversalis fascia
Spermatic cord
Innervation Cremaster is innervated by the genital branch of the
genitofemoral nerve, derived from the first and second lumbar spinal
nerves.
Actions Cremaster pulls the testis up towards the superficial inguinal
ring. Although it contains striated muscle fibres, it is not usually under
voluntary control. Stroking the skin of the medial side of the thigh
evokes a reflex contraction of the muscle, the cremasteric reflex, which
is most pronounced in boys. It may represent a protective reflex. The
cremaster may also have a role in testicular thermoregulation since it is
activated by the cold.
Inguinal canal
The inguinal canal is a natural passageway between the muscle layers Intercrural fibres
Cutaneous
of the anterior abdominal wall in the region of the groin (Figs 61.13–
neurovascular Inguinal ligament
61.15; see Figs 76.15, 76.16). Its size and form vary with age, and
bundles
although it is present in both sexes, it is best developed in the male.
The canal is an oblique tunnel, with deep (internal) and superficial
(external) openings or rings. It transmits the spermatic cord in males, Superficial Cut edge of skin


the round ligament of the uterus in females, and the ilioinguinal nerve inguinal and superficial
in both sexes. ring fascia
Spermatic
Superficial inguinal ring cord
The superficial inguinal ring is a hiatus in the aponeurosis of external Femoral sheath
Superficial
oblique, just above and lateral to the crest of the pubis. The ring is
inguinal
actually triangular, with its apex pointing laterally towards the anterior lymph nodes Femoral branch
of genitofemoral
superior iliac spine. Although it varies in size, it does not usually extend
nerve
laterally beyond the medial third of the inguinal ligament. The ring is
Superficial
smaller in the female. The base of the triangular opening lies along the Long (great)
dorsal vein
crest of the pubis. Its sides are the lateral and medial crura of the of penis saphenous vein
opening in the aponeurosis. The lateral crus is stronger and is attached
to the pubic tubercle. The medial crus is thinner and its fibres attach to
the front of the pubic symphysis and interlace with those from the
opposite side. A few intercrural fibres arch above the apex of the super- Fig. 61.13 Superficial structures of the inguinal region and lower part of
ficial inguinal ring (see Fig. 61.13). Some fibres from the external the anterior abdominal wall on the left side.


Anterior AbdominAl wAll
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Aponeurosis of Inferior epigastric
transversus abdominis vessels
Cut edge of
Deep inguinal ring
Cut edge of rectus internal oblique
abdominis
Cremaster
Spermatic
cord
Internal oblique
Reflected part
of inguinal
Iliohypogastric
ligament
nerve
Anterior
Ilioinguinal nerve
superior
Dorsal nerve Femoral canal iliac spine
of penis Femoral vein
Dorsal artery Femoral artery
of penis
Deep dorsal
vein of penis Femoral branch Inguinal ligament
of genitofemoral
Superficial
dorsal vein nerve Iliacus
of penis Long saphenous
vein (tributary) Femoral nerve
Femoral artery
Femoral vein
Fig. 61.14 Dissection of the regions shown in Figure 61.13, with part of
external oblique removed. Psoas major
Femoral canal
Ischium
Pubis
Interfoveolar ligament
Pubic
Transversalis fascia
tubercle
Conjoint tendon
Internal oblique
Transversalis Fig. 61.16 Deep structures of the inguinal canal. The aponeurosis of
fascia external oblique has been removed. For clarity, the fibres of internal
Transversus oblique and rectus abdominis have been divided, and the structures
Spermatic
abdominis passing posteroinferiorly to the inguinal ligament have been excluded.
cord
Deep circumflex
Conjoint tendon
iliac artery,
Inguinal ascending branch
ligament, Inferior epigastric
reflected part vessels (running in boundaries
medial border of The inguinal canal slants obliquely downwards and medially, parallel
Dorsal nerve deep ring)
to and just above the medial part of the inguinal ligament. It extends
of penis
Femoral canal from the deep to the superficial inguinal rings; the length depends on
Dorsal artery the age of the individual, but in the adult is between 3 and 6 cm long.
Femoral vein
of penis The canal is bounded anteriorly by skin, superficial fascia and the
Femoral artery


aponeurosis of external oblique. In its lateral third, the anterior wall is
Deep dorsal
vein of penis reinforced by the muscular fibres of the internal oblique just above their
origin from the iliopectineal arch. Posteriorly lie the reflected inguinal
Spermatic Genitofemoral ligament, the conjoint tendon and the transversalis fascia, which sepa-
cord nerve, rate it from extraperitoneal connective tissue and peritoneum. Superi-
femoral branch
orly lie the arched fibres of internal oblique and transversus abdominis,
Superficial
dorsal vein forming the conjoint tendon medially. Inferiorly is the union of the
of penis transversalis fascia with the inguinal ligament and, at the medial end,
the lacunar ligament.
Fig. 61.15 Dissection of the inguinal region and lower part of the anterior In the newborn, the deep and superficial rings are nearly superim-
abdominal wall on the left side, with parts of external and internal oblique posed and the canal is extremely short. In infants undergoing inguinal
muscles removed. hernia repair, the canal is only about 1 cm long (Parnis et al 1997). As
a child grows, the anterior abdominal wall muscles develop further,
causing the positions of the rings to separate and the canal to lengthen.
oblique aponeurosis and its overlying fascia continue downwards from The canal becomes progressively more oblique so that, by adulthood,
the crura of the ring over the spermatic cord, and form the delicate it has separate anterior and posterior walls, creating a ‘shutter’ effect. At
external spermatic fascia; consequently, the ‘ring’ appears less of a dis- the superficial ring and medial end of the anterior wall, where the canal
crete opening in the living. is weakest, the posterior wall is strengthened by the conjoint tendon
and reflected inguinal ligament. Increases in intra-abdominal pressure
deep inguinal ring transmitted to the posterior wall of the canal are resisted by contraction
The deep inguinal ring is an opening in the transversalis fascia, approxi- of the three anterolateral abdominal wall muscles. The fibres of internal
mately midway between the anterior superior iliac spine and the pubic oblique and transversus abdominis, which form the conjoint tendon,


symphysis, and about 1 cm above the inguinal ligament (Hale et al are constantly active in standing; this activity increases during episodes
2010). It is oval, with a roughly vertical long axis. Its size varies between of increased intra-abdominal pressure.
individuals but it is usually 1–2 cm wide in adults and larger in the male.
It is related above to the arched lower margin of transversus abdominis relations
and medially to the interfoveolar ligament (see Fig. 61.16). The inferior The inferior epigastric vessels are important medial relations of the deep
epigastric vessels run in the medial border of the deep inguinal ring. inguinal ring (Fig. 61.16). They lie on the transversalis fascia as they
Traction on the fascial ring exerted by contraction of internal oblique ascend obliquely behind the conjoint tendon to enter the rectus sheath.
may narrow the opening when intra-abdominal pressure is increased. The inguinal triangle (of Hesselbach) is an important clinical landmark


Hernias of the anterior abdominal wall
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related to the posterior wall of the inguinal canal and is best appreciated Clinical features of inguinal hernias
by examining the inguinal canal region from within the abdomen
(see Fig. 61.3). The triangle is bounded inferiorly by the medial third
Indirect inguinal hernias often descend from lateral to medial, follow-
of the inguinal ligament, medially by the lower lateral border of rectus
ing the path of the inguinal canal, whereas direct inguinal hernias tend
abdominis, and laterally by the inferior epigastric vessels.
to protrude more directly anteriorly. With the hernia reduced, pressure
applied over the region of the deep inguinal ring may prevent the
lacunar ligament
appearance of an indirect hernia on standing or straining, but distin-
The lacunar ligament is a triangular band of fibrous tissue lying mainly
guishing an indirect from a direct inguinal hernia by clinical examina-
posterior to the medial end of the inguinal ligament. It measures
tion alone is not reliable (Ralphs et al 1980, Tromp et al 2014). Direct
approximately 2 cm from base to apex and is a little larger in the male.
hernias are more likely to have a wide neck, making strangulation less
It is formed from fibres of the medial end of the inguinal ligament
likely.
together with fibres from the fascia lata of the thigh, which join
the medial end of the inguinal ligament from below (Lytle 1974). The
inguinal fibres run posteriorly and laterally to the medial end of the
UMBILICAL HERNIA
pectineal line and are continuous with the pectineal fascia. They form
a near-horizontal, triangular sheet with a curved lateral border, which
forms the medial border of the femoral canal. The apex of the triangle The most extreme variety of umbilical hernia is known as an ompha-
is attached to the pubic tubercle. A strong fibrous band, the pectineal locele or exomphalos, a congenital malformation in which abdominal


ligament, extends laterally along the pectineal line from the pectineal viscera, covered by a membrane, protrude through a wide umbilical
attachment of the lacunar ligament (Faure et al 2001). defect (Fig. 61.17). The defect arises from a failure of closure of the
umbilical ring after return of the herniated midgut loop in the embryo.
Myofascial flaps and component separation The most common variety of umbilical hernia is caused by a weakness
of the umbilical scar tissue, and is often seen in babies, especially those
of African descent. The vast majority of these will close spontaneously
during early childhood. Most umbilical hernias in adults are acquired
Available with the Gray’s Anatomy e-book
as a result of stretching of the supporting umbilical fascia and are due
to obesity and chronically increased intra-abdominal pressure (e.g.
from multiple pregnancies or ascites).
HERNIAS OF THE ANTERIOR ABDOMINAL WALL
A wide range of anterior abdominal wall hernias are described. These FEMORAL HERNIA
include inguinal, umbilical, incisional, para-umbilical, femoral, and
rarer types such as Spigelian hernias (Larson and Farley 2002; Dabbas The femoral sheath is continuous with the transversalis fascia anteriorly
et al 2011). and the iliopsoas fascia posteriorly (p. 1338). The medial compartment
of the sheath is the femoral canal, which typically contains lymphatics
embedded in loose adipose connective tissue. The opening of the canal
INGUINAL HERNIA
is the femoral ring, bounded anteriorly by the inguinal ligament, pos-
teriorly by the pectineal ligament, medially by the crescentic lateral
Although the inguinal canal is arranged such that the weaknesses in the
margin of the lacunar ligament and laterally by the femoral vein. A
anterior abdominal wall caused by the deep and superficial inguinal
femoral hernia protrudes through the femoral ring, which is normally
rings are supported, the region is a common site of herniation, particu-
closed by a femoral septum of extraperitoneal tissue, and is therefore a


larly in males. An inguinal hernia involves the protrusion of a viscus
site of potential weakness. In females, the ring is relatively wider and
through the tissues of the inguinal region of the abdominal wall.
changes during pregnancy, which helps to explain why femoral hernias
Indirect inguinal hernia account for about 20% of all groin hernias in women but less than 1%
of groin hernias in men (Whalen et al 2011). The ring also widens with
advancing age. Variations in the attachment of the pectineal part of the
An indirect inguinal hernia arises through the deep inguinal ring lateral
lacunar ligament may also be a factor.
to the inferior epigastric vessels. Many indirect hernias are related to the
When a tongue of omentum or a loop of intestine bulges through
abnormal persistence of a patent processus vaginalis, a tube-like exten-
the ring, it pushes out a hernial sac of peritoneum that is covered by
sion of peritoneum through the inguinal canal that is present during
extraperitoneal tissue (the femoral septum) and descends within the
normal development and normally becomes occluded after birth
femoral canal to the saphenous opening. It is prevented from descend-
(p. 1215). Others are acquired as a result of progressive weakening of
ing further by the configuration of the femoral sheath and by the attach-
the posterior wall of the inguinal canal in the region of the deep
ment of fascia to the inferior rim of the saphenous opening. The hernial
inguinal ring. The hernia may pass through the deep ring or may expand
sac hence turns forwards, stretching the cribriform fascia and curving
the deep ring such that it is no longer a clear entity. Small indirect
upwards over the inguinal ligament within the subcutaneous tissues.
hernias lie below and lateral to the fibres of the conjoint tendon, but
While in the canal, the hernia is usually small because it is contained
larger hernias often distort and thin the tendon superiorly. Small indi-
by the surrounding tissues, but it enlarges as it expands into the subcu-
rect hernias that do not protrude beyond the inguinal canal are covered
taneous tissues.


by the same inner layers as the spermatic cord: namely, the internal
The small size of some femoral hernias explains why they can be
spermatic fascia and cremaster. If the hernia extends through the super-
easily missed on examination, particularly in the obese. They are also
ficial inguinal ring, it is also covered by external spermatic fascia. In much more prone to strangulation than inguinal hernias (Whalen et al
hernias related to a persistent fully patent processus vaginalis, the
2011). The site of strangulation varies: it may be at the neck of the
hernia contents may descend as far as the tunica vaginalis anterior to hernial sac, or at the saphenous opening, but is most often at the junc-
the testis. In many individuals with a partial or fully patent processus
tion of the falciform margin of the saphenous opening with the free
vaginalis, an indirect hernia will manifest in childhood, but in others,
edge of the pectineal part of the inguinal ligament. When the lacunar
an actual hernia into the potential sac may not develop until adult life,
ligament is being divided to release the neck of the hernia, care must
often as a consequence of increased intra-abdominal pressure or sudden
be taken to avoid or control an aberrant obturator artery (see above).
muscular strain.
The pubic tubercle can be a useful landmark when attempting to
distinguish an inguinal from a femoral hernia; a femoral hernia lies
Direct inguinal hernia below and lateral to this landmark, whilst an inguinal hernia is above.
However, clinical differentiation of groin hernias can be relatively unre-
A direct inguinal hernia arises medial to the inferior epigastric vessels. liable (Hair et al 2001), prompting the use of imaging in suspected
Direct hernias are always caused by an acquired weakness of the cases (Whalen et al 2011).
posterior wall of the inguinal canal (see Fig. 61.3B); as they enlarge,
they frequently extend through the anterior wall of the inguinal
canal or superficial inguinal ring, becoming covered by external sper- SPIGELIAN HERNIA


matic fascia in the process. A direct inguinal hernia may closely resem-
ble an indirect hernia and can be difficult to distinguish on clinical A Spigelian hernia is a protrusion of preperitoneal fat or a peritoneal
examination. sac through a congenital or acquired defect in the abdominal wall in


Anterior abdominal wall
1081.e1
16
retPAHC
The goal of repairing massive ventral hernias lies in reapproximation
of the rectus sheath, thereby restoring anatomy and maximizing the
physiological potential of the abdominal wall. However, large fascial
defects often will not permit primary reapproximation without undue
tension. Many techniques have been developed that utilize the layered
nature of the abdominal wall musculature, allowing additional mobi-
lization of the fascial edges by ‘releasing’ incisions in myofascial layers
(Rosen 2011). This section reviews some of the more common tech-
niques. These repairs are often reinforced with synthetic or biopros-
thetic mesh applied in various ways: onlay (superficial to the fascia),
sublay (within the myofascial layers) or underlay (beneath the fascia
and exposed to intraperitoneal contents).
The Ramirez technique, originally described in 1990, refers to bilat-
eral release of the external oblique muscles, which can potentially
provide up to 10 cm, 20 cm and 8 cm of medial mobilization at the
upper, mid and lower abdomen, respectively (Ramirez et al 1990). A
disadvantage of this technique is that, in order to access and isolate the
external oblique muscles lateral to the linea semilunaris from a midline
incision, large subcutaneous flaps must be raised. This process neces-
A
sitates ligation of perforating vessels that supply the overlying subcuta-
neous tissue, rendering the flaps vulnerable to ischaemia, necrosis and
infection. In an attempt to overcome this limitation, an endoscopic
technique was developed to access the same myofascial layer through
smaller, lateral incisions. This technique obviates the need for large
subcutaneous flaps, a compromised blood supply, and the creation of
a large dead space for potential seroma formation. While reducing the
likelihood of wound necrosis and infection, the endoscopic technique
also reduces the maximum medial advancement by 1–2 cm on each
side. When release of the external oblique layer is insufficient, an addi-
tional 2–4 cm of fascial advancement can be gained by simultaneous
release of the posterior rectus sheath.
Often, the posterior rectus sheath can be incised independently of


external oblique release, allowing access to the retromuscular space and
providing several other options for medial advancement. The tradi-
tional Rives–Stoppa–Wantz technique, developed in the 1970s, involves
incising the posterior rectus sheath just lateral to the linea alba, allow-
ing a retromuscular dissection to the lateral edge of the rectus sheath.
If this does not gain sufficient medial advancement, further extension
can be obtained by release of transversus abdominis (Novitsky et al
2012). The posterior rectus sheath can be incised again 1–2 cm medial
to the linea semilunaris, safely preserving the laterally perforating neu-
rovascular bundles. This release exposes the underlying transversus
abdominis. Delicate transection of this muscle at its most medial inser-
tion allows access to a plane beneath transversus abdominis and super-
ficial to the transversalis fascia, preperitoneal fat and peritoneum. This
plane of dissection can be extended laterally to psoas major, inferiorly
to the space of Retzius, and superiorly beneath the diaphragm. The
same preperitoneal plane can be entered directly at the linea alba and
allows for lateral dissection, but does not provide the benefit of any
fascial advancement/release.
In addition to the medial mobilization of fascia aided by myofascial
flaps and component separations, these myofascial planes allow for
mesh reinforcement with extensive overlap without exposure to intra-
peritoneal contents (Heller et al 2012).
B
Fig. 61.17 A, A neonatal exomphalos. B, A persistent umbilical hernia in a
child. (A, B, Courtesy of Professor Mark Stringer.)


Anterior AbdominAl wAll
1082
8
noitCeS
the region of the intersection of the linea semilunaris with the arcuate 1995). There is currently little consensus among surgeons as to the
line (Skandalakis et al 2006, Larson and Farley 2002). Below this level, optimum method of repairing a large incisional hernia and numerous
the aponeuroses of external and internal oblique and transversus techniques are described (Cassar and Munro 2002). Needless to say, an
abdominis pass anterior to rectus abdominis and the posterior rectus understanding of abdominal wall anatomy is paramount to providing
sheath ends. A Spigelian hernia is an interstitial hernia in that the hernia a durable repair without compromising physiological function.
passes through a defect in the transversus and internal oblique aponeu-
roses but remains deep to the overlying external oblique aponeurosis.
Bonus e-book images and table
It is frequently associated with diagnostic delay.
INCISIONAL HERNIA Fig. 61.17 A, A neonatal exomphalos. B, A persistent umbilical
hernia in a child.
Incisional hernias now comprise as many as 20% of all anterior abdom-
inal wall hernias. This complication of abdominal laparotomy incisions Table 61.1 Distances of superior and deep inferior epigastric
is due to technical failures, wound infection, and patient-related factors arteries from midline.
such as obesity, medical comorbidities and old age (Carlson et al
KEY REFERENCES
Carlson MA, Ludwig KA, Condon RE 1995 Ventral hernia and other com- A description of the novel technique for posterior component separation,
plications of 1,000 midline incisions. South Med J 88:450–3. which was associated with a low perioperative morbidity and a low
A summary of the outcomes in 1079 consecutive clean or clean- recurrence rate. Overall, transversus abdominis release may be an important
contaminated midline abdominal incisions closed with running 0-loop nylon addition to the armamentarium of surgeons undertaking major abdominal
suture after both elective and emergency operations done between 1984 and wall reconstructions.
1991.
Ramirez OM, Ruas E, Dellon AL 1990 ‘Components separation’ method for


Cassar K, Munro A 2002 Surgical treatment of incisional hernia. Br J Surg closure of abdominal wall defects: an anatomic and clinical study. Plast
89:534–45. Reconstr Surg 86:519–26.
A review that compares the long-term recurrence rates of open primary Closure of large abdominal wall defects usually requires the transposition of
repair with open mesh and laparoscopic repair, citing the inadequacy of remote myocutaneous flaps or free-tissue transfers. The purpose of this study
open primary repair. was to determine if separation of the muscle components of the abdominal
wall would allow mobilization of each unit over a greater distance than is
El-Mrakby HH, Milner RH 2002 The vascular anatomy of the lower anterior
possible by mobilization of the entire abdominal wall as a block.
abdominal wall: a microdissection study on the deep inferior epigastric
vessels and the perforator branches. Plast Reconstr Surg 109:539–43; Rosen MJ 2011 Atlas of abdominal wall reconstruction. Philadelphia,
discussion 44–7. London: Saunders.
An account of how the deep inferior epigastric artery provides the main A text that summarizes the relevant anatomy of the abdominal wall,
blood supply to the lower abdominal wall. Microdissection of the artery, its relating this to techniques for abdominal wall reconstructions.
main branches and the perforator vessels was undertaken in 20 cadavers
Saber AA, Meslemani AM, Davis R et al 2004 Safety zones for anterior
and the findings summarized.
abdominal wall entry during laparoscopy: a CT scan mapping of
Heller L, McNichols CH, Ramirez OM 2012 Component separations. Semin epigastric vessels. Ann Surg 239:182–5.
Plast Surg 26:25–8. Trauma to abdominal wall blood vessels occurs in 0.2–2% of laparoscopic
A description of how, since its original description, the components procedures. Both superficial and deep abdominal wall vessels are at risk. The
separation technique underwent multiple modifications with the ultimate superficial vessels may be located by transillumination; however, the deep
goal of decreasing the morbidity associated with the traditional procedure. epigastric vessels cannot be effectively located by transillumination and, thus,


The extensive subcutaneous lateral dissection had been associated with other techniques should be used to minimize the risk of injury to these vessels.
ischaemia of the midline skin edges, wound dehiscence, infection and This study utilizes CT scans to map the pathway of the epigastric vessels.
seroma. Although the current trend is to proceed with minimally invasive
Skandalakis PN, Zoras O, Skandalakis JE et al 2006 Spigelian hernia: surgi-
component separation and to reinforce the fascia with mesh, the basic
cal anatomy, embryology, and technique of repair. Am Surg 72:42–8.
principles of the techniques, as described by Ramirez et al in 1990, have not
An account of Spigelian hernia (1–2% of all hernias), the protrusion of
changed over the years.
preperitoneal fat, peritoneal sac or organ(s) through a congenital or acquired
Larson DW, Farley DR 2002 Spigelian hernias: repair and outcome for 81 defect in the Spigelian aponeurosis (i.e. the aponeurosis of the transverse
patients. World J Surg 26:1277–81. abdominal muscle limited by the linea semilunaris laterally and the lateral
An account of Spigelian hernia, a rare partial abdominal wall defect. The edge of the rectus muscle medially). Mostly, these hernias lie in the ‘Spigelian
frequent lack of physical findings, along with vague associated abdominal hernia belt’, a transverse 6 cm-wide zone above the interspinal plane; lower
complaints, makes the diagnosis elusive. A retrospective review of Mayo hernias are rare and should be differentiated from direct inguinal or
Clinic patients was performed to find all patients who had undergone supravescical hernias. Although named after Adriaan van der Spieghel, the
surgical repair of a Spigelian hernia from 1976 to 1997. semilunar line (linea Spigeli) was only described by Spieghel in 1645. Josef
Klinkosch first defined the Spigelian hernia as a defect in the semilunar line
Novitsky YW, Elliott HL, Orenstein SB et al 2012 Transversus abdominis


in 1764. Defects in the aponeurosis of transverse abdominal muscle (mainly
muscle release: a novel approach to posterior component separation
under the arcuate line and more often in obese individuals) have been
during complex abdominal wall reconstruction. Am J Surg 204:
considered as the principal aetiological factor.
709–16.


Anterior abdominal wall
1082.e1
16
retPAHC
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48:163–9. cal relationship between the proximal attachment of adductor longus
Carlson MA, Ludwig KA, Condon RE 1995 Ventral hernia and other com- and the distal rectus sheath. Clin Anat 26:522–30.
plications of 1,000 midline incisions. South Med J 88:450–3. Novitsky YW, Elliott HL, Orenstein SB et al 2012 Transversus abdominis
A summary of the outcomes in 1079 consecutive clean or clean- muscle release: a novel approach to posterior component separation
contaminated midline abdominal incisions closed with running 0-loop nylon during complex abdominal wall reconstruction. Am J Surg 204:
suture after both elective and emergency operations done between 1984 and 709–16.
1991. A description of the novel technique for posterior component separation,
which was associated with a low perioperative morbidity and a low
Cassar K, Munro A 2002 Surgical treatment of incisional hernia. Br J Surg
recurrence rate. Overall, transversus abdominis release may be an important
89:534–45.
addition to the armamentarium of surgeons undertaking major abdominal
A review that compares the long-term recurrence rates of open primary
wall reconstructions.
repair with open mesh and laparoscopic repair, citing the inadequacy of
open primary repair. Pai MM, Krishnamurthy A, Prabhu LV et al 2009 Variability in the origin of
the obturator artery. Clinics (Sao Paulo) 64:897–901.
Chopra J, Rani A, Rani A et al 2011 Re-evaluation of superficial fascia of


anterior abdominal wall: a computed tomographic study. Surg Radiol Parnis SJ, Roberts JP, Hutson JM 1997 Anatomical landmarks of the inguinal
Anat 33:843–9. canal in prepubescent children. Aust N Z J Surg 67:335–7.
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El-Mrakby HH, Milner RH 2002 The vascular anatomy of the lower anterior Ramirez OM, Ruas E, Dellon AL 1990 ‘Components separation’ method for
abdominal wall: a microdissection study on the deep inferior epigastric closure of abdominal wall defects: an anatomic and clinical study. Plast
vessels and the perforator branches. Plast Reconstr Surg 109:539–43; Reconstr Surg 86:519–26.
discussion 44–7. Closure of large abdominal wall defects usually requires the transposition of
An account of how the deep inferior epigastric artery provides the main remote myocutaneous flaps or free-tissue transfers. The purpose of this study
blood supply to the lower abdominal wall. Microdissection of the artery, its was to determine if separation of the muscle components of the abdominal
main branches and the perforator vessels was undertaken in 20 cadavers wall would allow mobilization of each unit over a greater distance than is
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frequent lack of physical findings, along with vague associated abdominal An account of Spigelian hernia (1–2% of all hernias), the protrusion of
complaints, makes the diagnosis elusive. A retrospective review of Mayo preperitoneal fat, peritoneal sac or organ(s) through a congenital or
Clinic patients was performed to find all patients who had undergone acquired defect in the Spigelian aponeurosis (i.e. the aponeurosis of the
surgical repair of a Spigelian hernia from 1976 to 1997. transverse abdominal muscle limited by the linea semilunaris laterally and
the lateral edge of the rectus muscle medially). Mostly, these hernias lie in


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Posterior abdominal wall and CHAPTER
62
retroperitoneum
THORACOLUMBAR FASCIA
DEFINITIONS, BOUNDARIES AND CONTENTS
The thoracolumbar fascia is composed of a complex arrangement of
The posterior abdominal wall does not have an agreed uniform defini- multiple fascial layers that is most prominent at the caudal end of the
tion. It represents the posterior boundary of the abdominal cavity. In lumbar spine (Ch. 43) (Willard et al 2012). In the lumbar region, it is
common with the anterior and lateral abdominal walls, it is composed often described as having three layers (Figs 62.1–62.3, see Fig. 43.6). The
of several layers (skin, superficial fascia, muscle, extraperitoneal fat/ posterior layer is attached medially to the spines of the lumbar vertebrae
fascia and parietal peritoneum). The vertebral column and paraverte- and to the supraspinous ligament; it has a superficial lamina (the
bral muscles of the back are part of the posterior abdominal wall, but aponeurosis of latissimus dorsi) and a deep lamina that covers the pos-
are usually not considered in this context. The posterior abdominal wall terior surface of the paraspinal muscles. The middle layer is attached
is continuous with the posterior thoracic wall at the posterior attach- medially to the tips of the transverse processes of the lumbar vertebrae
ment of the diaphragm, with the posterior wall of the pelvis inferiorly, and extends laterally behind quadratus lumborum; inferiorly, it attaches
and with the anterolateral abdominal wall laterally. to the iliac crest, and superiorly to the lower border of the twelfth rib.
The retroperitoneum is a three-dimensional compartment bounded The anterior layer covers the anterior surface of quadratus lumborum
anteriorly by the parietal peritoneum of the posterior abdominal wall and is attached medially to the transverse processes of the lumbar verte-
and superiorly by the diaphragm. Inferiorly and laterally, it is continu- brae behind psoas major. Laterally, it fuses with the transversalis fascia
ous with the extraperitoneal connective tissues lining the pelvis and and the aponeurosis of transversus abdominis. Inferiorly, it is attached


anterolateral abdominal wall, respectively. The posterior boundary of to the iliolumbar ligament and adjoining iliac crest. Superiorly, it is
the retroperitoneum is variably defined, depending on whether the attached to the inferior border of the twelfth rib and extends to the
psoas muscles and quadratus lumborum are regarded as contents or transverse process of the first lumbar vertebra, forming the lateral arcuate
boundaries of this compartment. ligament of the diaphragm. The posterior and middle layers of the tho-
The posterior abdominal wall and the retroperitoneum are related racolumbar fascia fuse at the lateral margin of the paraspinal muscles
but different concepts. The retroperitoneum is a compartment and a (the so-called ‘lateral raphe’), thereby enclosing the paraspinal muscles
three-dimensional space, a concept invoked when localization, spread in an osteofascial compartment. Although contained in layers of thora-
and containment of disease are primary considerations. The posterior columbar fascia, the paraspinal muscles are conceptualized as part of ‘the
abdominal wall is a part of the parietal coverings of abdominal viscera, back’. The aponeurosis of transversus abdominis fuses with both the
a concept invoked when considering posteriorly directed surgery from anterior layer of thoracolumbar fascia at the lateral margin of quadratus
within the abdomen, posterolateral access to retroperitoneal organs lumborum and with the lateral raphe behind quadratus lumborum.
(e.g. nephrectomy or percutaneous endoscopic renal access), or else in
contradistinction to the anterior abdominal wall. Advances in cross-
sectional imaging have promoted a better understanding of the anatomy ILIOPSOAS FASCIA
of the retroperitoneum, particularly its compartmental anatomy, and
with it the retroperitoneum has become the more prevalent clinical Psoas fascia
concept outside of specific surgical circumstances.
The retroperitoneum houses the paired viscera originating from the A relatively dense layer of fascia covers the anterior surface of psoas
embryonic extracoelomic space: the kidneys and ureters (Ch. 74), and major. Medially, it is continuous with the attachments of the muscle to
the suprarenal glands (Ch. 71) and their vessels and nerves. It also the transverse processes and bodies of the lumbar vertebrae and the


houses the unpaired derivatives of the embryonic intracoelomic gut tendinous arches. Laterally, the fascia blends with the fascia over quad-
tube secondarily retroperitonealized: the duodenum (Ch. 65), the pan- ratus lumborum above and is continuous with the iliac fascia below.
creas (Ch. 69), and the ascending and descending colon (Ch. 66) and Superiorly, the fascia merges with the medial arcuate ligament, while,
their vessels and nerves. inferiorly, it extends down into the thigh around the iliopsoas tendon.
Attached to the retroperitoneum are the mesenteries of the small The psoas fascia separates the anterior surface of the muscle and the
bowel (Ch. 65), transverse and sigmoid colons (Ch. 66), and the peri- lumbar plexus within it from the retroperitoneal structures lying ante-
toneal ligaments of the liver (Ch. 67) and spleen (Ch. 70). riorly. A psoas abscess, which can arise by haematogenous seeding or
The retroperitoneum contains the abdominal aorta and branches; from direct extension of infection from adjacent structures (e.g. the
the inferior vena cava and tributaries; the origins of the azygos and spine, kidneys or colon), often tracks along the muscle within the fascia,
hemiazygos veins; the pre- and para-aortic (lumbar) lymph nodes, and, rarely, may ‘point’ in the groin.
cisterna chyli and the origin of the thoracic duct (Ch. 56); the diaphrag-
matic crura (Ch. 55); the lumbar plexus and lumbosacral trunk; and Iliac fascia
the autonomic plexuses of the abdomen (Ch. 59).
The iliac fascia overlies iliacus. Superiorly and laterally, it is attached to
the inner aspect of the iliac crest, and medially it blends with the ante-
SKIN AND SOFT TISSUES
rior layer of thoracolumbar fascia over quadratus lumborum and with
the psoas fascia. Inferiorly and laterally, it continues into the thigh to
The skin of the posterior abdominal wall is supplied by musculocutane- fuse with the femoral sheath, while medially, it is attached to the peri-


ous branches of the lumbar arteries and veins, and innervated by the osteum of the ilium and iliopubic eminence at the pelvic brim. Both
dorsal rami of the lower thoracic and lumbar spinal nerves. However, the femoral nerve and lateral femoral cutaneous nerve lie under the iliac
the cutaneous distribution of the dorsal rami of L4 and L5 is variable fascia in the pelvis, where they can be targeted for image-guided nerve
and controversial (Lee et al 2008). blocks (Hebbard et al 2011).
In the muscular posterior abdominal wall, intermuscular fascial
layers delineate compartments and provide the conceptual anatomical
framework. In the retroperitoneum, the compartments (the clinical VISCERAL FASCIAE
synonym is ‘spaces’) and their interrelationships provide the conceptual
framework, particularly in cross-sectional anatomy, with the dividing The organization of the retroperitoneum is most easily conceptualized
fasciae often hard to visualize unless outlined by disease processes. in terms of compartments (synonym: spaces) rather than fasciae (Dodds 1083


Posterior abdominal wall and retroPeritoneum
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8
noitCes
Anterior perirenal fascia fused with posterior peripancreatic fascia
Posterior parietal peritoneum
Retromesocolic fascia (of Toldt) fused with anterior peripancreatic fascia
Ascending (fourth) part of duodenum
Anterior leaf of descending mesocolon
Root of transverse mesocolon
Descending mesocolon
Peritoneal cavity
Middle colic vessels fenestrating the
anterior peripancreatic fascia Descending colon
Anterior perirenal fascia (fused with retrocolic/mesocolic fascia)
Body of pancreas
Paracolic gutter
Splenic vein Lateral abdominal parietal peritoneum
Peripancreatic space
Extraperitoneal fat
Abdominal aorta
Kidney
Transversus abdominis
Renal vessels
Crus of diaphragm
Internal oblique
Body of L1 vertebra
External oblique
Psoas major
Psoas fascia Lateroconal fascia
Left (descending) pericolic space
Erector spinae Posterior perirenal fascia
Perirenal space
Aponeurosis of latissimus dorsi (superficial lamina of posterior layer of thoracolumbar fascia)
Posterior pararenal space
Thoracolumbar fascia
Latissimus dorsi
Middle layer of
thoracolumbar fascia Fascia over quadratus lumborum
Deep lamina of posterior layer of thoracolumbar fascia Quadratus lumborum
Lateral raphe
Anterior layer of thoracolumbar fascia
Fig. 62.1 Compartments and fasciae of the upper retroperitoneum (left side). A transverse section at approximately the level of the first lumbar vertebra,
showing the location and relations of the peripancreatic space.
Anterior perirenal Peritoneum
fascia fused with Descending Internal oblique
Kidney Descending retrocolic/mesocolic fascia Gonadal vessels colon External
colon Transversus oblique
Ureter Retroperitoneal 'space'
Left colic artery Peritoneum abdominis
Psoas
Ureter
major Transversus
Branches of abdominis Anterior and posterior
layers of the lower
lumbar plexus
extension of the
perirenal fascia
Common Retrocolic/
iliac vessel mesocolic
fascia


Obturator
nerve Lateral femoral
cutaneous nerve
Psoas
major
External
oblique
Iliac fascia
Internal
oblique L5 vertebra Psoas fascia
Lateroconal Ilium
fascia
Iliacus
Thoracolumbar Posterior
fascia Femoral nerve
perirenal Body of
L3 vertebra Latissimus fascia Genitofemoral nerve
dorsi
Deep muscles
of the back Fascia over Fig. 62.3 Compartments and fasciae of the lower retroperitoneum (left
Psoas fascia quadratus lumborum side). A transverse section at approximately the L4 vertebral level,
showing the location and relations of the pericolic space.
Quadratus Ilioinguinal
lumborum nerve
Fig. 62.2 Compartments and fasciae of the mid-retroperitoneum (left eponym for different fasciae; different eponyms have been used to refer
side). A transverse section at approximately the level of the third lumbar to the same fascia. Thus, ‘Gerota’s fascia’ has been used to refer to the
vertebra, showing the location and relations of the perirenal space. entire perirenal fascia or to its anterior or posterior layers (Chesbrough
et al 1989). ‘Toldt’s fascia’ has been used to refer to the fusion fascia
et al 1986). The fasciae bounding the compartments limit or direct the behind the ascending or descending colon (Culligan et al 2013), or to
spread of blood, fluid, gas or malignant disease, but are variable and the posterior perirenal fascia, or to the fusion fascia behind the tail of
often difficult to see with cross-sectional imaging. the pancreas (Kimura et al 2010). ‘Zuckerkandl’s fascia’ has been used
The fascial layers located between the posterior parietal peritoneum to refer to the posterior or anterior perirenal fascia (Chesbrough et al
and the quadratus lumborum have been described in confusing epony- 1989). ‘Treitz’s fascia’ has been used to refer to the fusion fascia behind
mous terms in the literature. Different authors have used the same the head of the pancreas (Kimura et al 2010).


muscles
1085
26
retPaHC
The concept of ‘fusion fascia’ describes a retroperitoneal fascia medially with the mesocolon (see Figs 62.1–62.3). The pericolic spaces
formed by the fusion of an embryonic mesentery with embryonic retro- contain a variable amount of fat and are limited anteriorly, superiorly
peritoneum. It is an avascular layer that allows a dissection plane to be and laterally by the colonic serosa. Inferiorly, the pericolic spaces are
developed, and also limits the spread of disease. The retropancreati- continuous with the retroperitoneal spaces of the iliac fossae. Posteri-
coduodenal fascia and the retrocolic/retromesocolic fascia (right and orly, each pericolic space is limited by a fusion fascia formed by the
left) are fusion fascias, and delimit their respective compartments. They right leaf of the embryonic mesocolon fusing to the left leaf of the
were first described in detail by the Austrian anatomist Carl Toldt, and embryonic duodenal mesentery and embryonic retroperitoneum further
only later reported in the English literature (Congdon et al 1942). laterally. This retrocolic fascia (of Toldt) (Culligan et al 2013, Culligan
Traditional compartmental anatomy of the retroperitoneum divides et al 2014) forms the classic bloodless plane of dissection when per-
it into the anterior and posterior pararenal spaces, and the perirenal forming a hemicolectomy. Its plane is entered by incising the junction
space. ‘Anterior pararenal space’ describes the compartment between of the colonic serosa with the parietal peritoneum at the white line (of
the posterior peritoneum and the anterior perirenal fascia. This is an Toldt) in the paracolic gutter. Radiologically, the retrocolic fascia may
oversimplification and is unable to explain all patterns of disease con- be indistinguishable from the anterior perirenal fascia when lateral to
tainment or spread. The smallest set of compartments sufficient to the duodenum and pancreas.
explain most such phenomena is as follows. Variation in colonic retroperitonealization may produce a free


mesocolic pedicle instead (most commonly seen at the caecum).
Perirenal space
Lateroconal fascia
Lateroconal fascia was originally defined as the fascial layer extending
The paired perirenal space is bounded by the perirenal fascia, which
from the junction of the anterior and posterior perirenal fasciae to
envelops the kidney and suprarenal gland on each side. Perirenal fascia
the parietal peritoneum in the lateral paracolic gutter (Congdon and
is traditionally described as having anterior and posterior layers, which
Edson 1941). It is better understood as the lateral extension of the
are continuous with each other laterally (see Figs 62.1–62.3; Ch. 74).
retrocolic fusion fascia that blends with the parietal peritoneum (see
The perirenal fascia can usually be identified on cross-sectional imaging
Figs 62.1–62.3).
as a thin layer surrounding the kidney and suprarenal gland, separated
The various compartments described above are illustrated in the
from the renal capsule by a variable amount of perirenal fat. Inferiorly,
context of clinical disease in Figures 62.4–62.6.
the perirenal space continues down around the ureter but becomes
progressively narrower and may or may not extend into the pelvic ret-
roperitoneum. Medially, the two perirenal spaces may interconnect
BONES
anterior to the aorta and inferior vena cava (Kneeland et al 1987). The
existence of a fascial partition separating the kidney and ipsilateral
suprarenal gland within the perirenal fascial envelope is controversial The posterior abdominal wall is supported by the vertebral column and
(Amin et al 1976). bony pelvis. The individual bones are the lower two ribs, the twelfth
thoracic and five lumbar vertebrae, and the sacrum and ilium, together
Anterior and posterior pararenal spaces with their interconnecting ligaments (Chs 43, 53).
The anterior pararenal space (an oversimplification) refers to the region
MUSCLES
between the anterior layer of perirenal fascia and the posterior parietal
peritoneum; it is not a single compartment. On the right, it contains


the second part of the duodenum, ascending colon and its mesentery, The majority of the muscles of the posterior abdominal wall are func-
and on the left, the fourth part of the duodenum, descending colon tionally part of the lower limb or vertebral column. They provide the
and its mesentery (see Figs 62.1–62.3). surface against which the neurovascular and visceral structures of the
The potential compartment between the posterior layer of perirenal retroperitoneum lie (Fig. 62.7; see Fig. 62.14).
fascia and the thoracolumbar and psoas fasciae on each side is the
Quadratus lumborum
posterior pararenal space. It contains a variable amount of fat. Laterally,
it is continuous with the extraperitoneal (properitoneal) fat of the Quadratus lumborum is an irregularly shaped quadrilateral muscle,
anterolateral abdominal wall, and inferiorly, with the retroperitoneal broader at its inferior attachment than superiorly.
fat overlying iliacus and the pelvic wall, and the perivesical fat (Coffin
et al 2015). Attachments The inferior attachment is by aponeurotic fibres to the
When the ascending or descending colon is retrorenal (an anatomi- iliac crest over an area 5–7 cm lateral to the tip of the L4 transverse
cal variant), the colon and pericolic space lie in a groove between the process and/or the iliolumbar ligament. The superior attachment is to
posterior layer of perirenal fascia and the posterior pararenal space. the lower anterior surface of the twelfth rib, the lateral surface of the
twelfth thoracic vertebra, and the apices of the transverse processes of
Peripancreatic space the upper four lumbar vertebrae. Fascicles vary in number and size but
are arranged in three layers: anterior, middle and posterior (Phillips
et al 2008).
The peripancreatic space contains the duodenum and pancreas along
with the origins of the superior mesenteric vessels and the retroperito-
Relations Anteriorly are the colon (ascending on the right, descend-
neal segments of the common bile duct, portal vein and hepatic artery.
ing on the left), kidney, psoas major and minor, and diaphragm. The


The posterior boundary is a fusion fascia formed by fusion of the
subcostal, iliohypogastric and ilioinguinal nerves lie on the fascia ante-
embryonic duodenal mesentery to the embryonic retroperitoneum
rior to the muscle, bound down to it by the medial continuation of the
(Dodds et al 1986). This fascia is termed ‘retropancreatic’ or ‘retropan-
transversalis fascia.
creaticoduodenal’ fascia in the imaging literature, and ‘fusion fascia of
Treitz’ in the surgical literature (Kimura et al 2010). The fascia forms a
Vascular supply Quadratus lumborum is supplied by branches of
relatively bloodless dissection plane, used to mobilize the duodenum
the lumbar arteries, the arteria lumbales imae from the median sacral
and head of the pancreas.
artery, the lumbar branch of the iliolumbar artery, and branches of the
The lateral extent of the peripancreatic space is variable; it lies pos-
subcostal artery.
terior to the ascending and descending colon and anterior to the peri-
renal space (see Fig. 62.1). At the tail of the pancreas, the peripancreatic
Innervation The muscle is innervated by the ventral rami of the
space lies in continuity with the splenorenal ligament. Anteriorly, it is
twelfth thoracic and upper three or four lumbar spinal nerves.
in continuity with the transverse mesocolon and small bowel mesen-
tery. Consequently, peripancreatic fluid collections may extend into
Actions Quadratus lumborum fixes the twelfth rib, and acts as a
both mesenteries and extend posterior to the ascending and descending
muscle of inspiration by helping to stabilize the lower attachments of
colon but do not usually cross into the perirenal and pericolic spaces.
the diaphragm. With the pelvis fixed, unilateral contraction flexes the
vertebral column to the same side, and bilateral contraction probably
Pericolic spaces
helps to extend the lumbar part of the vertebral column. These actions
on the lumbar spine are reported to be weak (Phillips et al 2008) and
The ascending and descending pericolic spaces are narrow compart- yet the muscle undergoes considerable hypertrophy in some sporting


ments surrounding the respective parts of the colon and in continuity activities (Ranson et al 2008).


Posterior abdominal wall and retroPeritoneum
1086
8
noitCes
18
9
7 2 10
8
10
6
19 3 17 4 5 6 7
4
1 5 2 1
20 8 4 12 3 14
10 9 11 4 23 26 25 13
21 11 19 23
14 16 20 27 24 15
22 22
15 12 13 16 18
23 21 29 28 17
24
A B
3 9
9
8
7
4
3
2 5
2
10 1
4
7
5
1 5
6
8
7 5
7
14
11
6
12
13
C D
Fig. 62.4 A 58-year-old male with chronic pancreatitis and a peripancreatic pseudocyst. Oral and intravenous contrast-enhanced computed tomography
(CT; axial and sagittal planes). The pseudocyst, containing gas and fluid, has expanded the peripancreatic space. The fusion fasciae forming the
boundaries of the peripancreatic space are thickened through chronic inflammation and are easily visible. A, A transverse section at the level of the body
of the second lumbar vertebra. Key: 1, neck of pancreas; 2, gas in anterior part of collection (outlining peripancreatic space); 3, fluid and debris in
posterior (dependent) part of collection (outlining peripancreatic space); 4, retropancreatic fusion fascia (anterior perirenal fascia fused to right leaf of
mesoduodenum); 5, anterior peripancreatic fascia fused to right leaf of left mesocolon; 6, anterior peripancreatic fascia deep to left mesocolon and
collapsed lesser sac; 7, anterior peripancreatic fascia fused to peritoneum of lesser sac in gastric bed; 8, superior mesenteric artery; 9, abdominal aorta;
10, inferior vena cava; 11, left renal vein; 12, left kidney parenchyma; 13, left perirenal space (not distinguishable from left posterior pararenal space);


14, right kidney parenchyma; 15, right perirenal space (not distinguishable from right posterior pararenal space); 16, upper L2 vertebral body; 17, splenic
flexure; 18, stomach (elevated and compressed by collection); 19, gallbladder; 20, right lobe of liver (segments 5 and 6); 21, right crus of diaphragm;
22, origin of left psoas major; 23, left quadratus lumborum; 24, left erector spinae group. B, A transverse section at the level of the body of the fourth
lumbar vertebra. Key: 1, inferior part of body and uncinate process of pancreas; 2, distal second part of duodenum; 3, third part of duodenum; 4,
peripancreatic space collection (around and anterior to pancreas and duodenum); 5, superior mesenteric vein; 6, superior mesenteric artery; 7, small
bowel mesentery; 8, part of collection dissecting into transverse mesocolon; 9, transverse mesocolon (fused to greater omentum); 10, transverse colon;
11, collection dissecting behind ascending colon; 12, ascending colon; 13, collection (with gas) dissecting behind descending colon; 14, descending
colon; 15, left kidney parenchyma; 16, left perirenal space; 17, left posterior perirenal fascia (normal thickness, therefore faint); 18, left posterior pararenal
space; 19, right kidney parenchyma; 20, right perirenal space; 21, right posterior perirenal fascia; 22, right posterior pararenal space; 23, anterior
pararenal fascia (thickened through chronic inflammation); 24, upper L4 vertebral body; 25, abdominal aorta; 26, inferior vena cava; 27, right psoas
major; 28, left quadratus lumborum; 29, left erector spinae group. C, A mid-sagittal section. Key: 1, neck of pancreas; 2, gas in anterior part of


collection; 3, fluid in posterior part of collection; 4, coeliac trunk; 5, superior mesenteric artery; 6, left renal vein; 7, abdominal aorta; 8, diaphragmatic
crura; 9, left lobe of liver; 10, antrum of stomach (collapsed); 11, part of collection dissecting into transverse mesocolon; 12, transverse colon; 13, part
of collection dissecting into small bowel mesentery; 14, third part of duodenum. D, A left sagittal section through left renal hilum. Key: 1, body of
pancreas; 2, fluid collection; 3, fundus of stomach (containing oral contrast); 4, body of stomach (containing oral contrast and displaced); 5, left anterior
perirenal fascia fused with retropancreatic fascia; 6, left anterior perirenal fascia fused with right leaf of left mesocolon (fusion fascia of Toldt); 7, fourth
part of duodenum; 8, left kidney parenchyma; 9, spleen.


Vascular supply and lymphatic drainage
1087
26
retPaHC
5
11
6
10 15
7
9
8
4
12
3
1 2
4 19
1 11
3 3 3 10 14
2 13
3 6 15
5
6 12 17 16
9
18
7 13
8
14
A B
Fig. 62.5 A 43-year-old male with subacute retrocaecal appendicitis. Inflammatory fluid and stranding in the right pericolic space. The fused right
anterior perirenal fascia and right mesocolon (the fusion fascia of Toldt) is visible. A, A transverse section through the vermiform appendix. Key: 1,
thickened and inflamed retrocaecal appendix; 2, inflammatory fluid tracking posteriorly in right pericolic space, anterior to right perirenal space; 3,
anterior perirenal fascia (fused with retrocolic/mesocolic) fascia; 4, caecum/ascending colon; 5, right kidney parenchyma; 6, right perirenal space
7, right posterior pararenal space (the posterior perirenal fascia is difficult to identify); 8, right quadratus lumborum; 9, right psoas major; 10, inferior
vena cava; 11, abdominal aorta; 12, left psoas major; 13, left quadratus lumborum; 14, left erector spinae group; 15, left kidney parenchyma; 16, left
posterior perirenal fascia; 17, left perirenal space; 18, left posterior pararenal space; 19, descending colon. B, A coronal section through the appendix.
Key: 1, thickened and inflamed retrocaecal appendix; 2, inflammatory fluid and oedema extending along right mesocolon towards root of mesentery;
3, enlarged inflamed right ileocolic lymph node; 4, inflammatory fluid tracking in right mesocolon; 5, inferior vena cava – retrohepatic segment; 6,


inferior vena cava – infrahepatic peritonealized segment; 7, inferior vena cava – renal segment; 8, inferior vena cava – infrarenal segment; 9, left renal
vein; 10, superior mesenteric artery; 11, coeliac trunk; 12, abdominal aorta; 13, right common iliac artery; 14, left common iliac artery (origin); 15, tail of
pancreas.
Psoas major, psoas minor and iliacus
Psoas major and iliacus are functionally important in the lower limb
and are described together with psoas minor in Chapter 80.
Posterior abdominal wall hernias
In the absence of a previous surgical incision, herniation through the
posterior abdominal wall is rare because the muscular and fascial layers
4 usually protect against protrusion of the posterior abdominal viscera,
which are relatively immobile. However, the posterior free border of
7 4
external oblique, the inferior free border of latissimus dorsi, and the
8 6 iliac crest delimit the lumbar triangle (of Petit), an area of potential
9
13 14 weakness through which a lumbar hernia may develop (Stamatiou et al
2 2009).
5
10
1
3
11 VASCULAR SUPPLY AND LYMPHATIC DRAINAGE
3
12 ABDOMINAL AORTA
The abdominal aorta begins at the aortic hiatus of the diaphragm,
anterior to the twelfth thoracic vertebra (Mirjalili et al 2012a). It
descends anterior to the lumbar vertebrae and bifurcates into two
Fig. 62.6 A 61-year-old male with mid-ureteric calculus causing high-
common iliac arteries anterior to the fourth lumbar vertebra or the L4/5
grade obstruction of the left ureter and extravasation of urine from the left
intervertebral disc, slightly to the left of the midline (Mirjalili et al
renal hilum. Oral and intravenous contrast-enhanced CT. A transverse
2012b, Moussallem et al 2012) (Figs 62.8–62.10). The angle of bifurca-
section through the left renal hilum (the calculus is below the plane of this


tion is very variable (Moussallem et al 2012). The mean adult infrarenal
section). Key: 1, left kidney parenchyma; 2, extravasated urine in left
aortic diameter measured by computed tomography is 19–21 mm in
perirenal space; 3, posterior perirenal fascia; 4, anterior perirenal fascia
(fused medially with retropancreatic fascia and fused laterally with right men and 16–18 mm in women (Rogers et al 2013), but there are ethnic
leaf of descending mesocolon); 5, left posterior pararenal space; 6, variations (Jasper et al 2014). Measured by ultrasound, equivalent
descending colon; 7, third part of duodenum; 8, inferior vena cava; 9, values are 20 mm (SD 2.5 mm) in men and 17 mm (SD 1.5 mm) in
abdominal aorta; 10, right psoas major; 11, right quadratus lumborum; women (Needleman 2006). The mean calibre of the abdominal aorta
12, right erector spinae group; 13, aortocaval lymph node (borderline decreases slightly from proximal to distal. With advancing age, there is
enlarged); 14, left para-aortic lymph nodes (borderline enlarged). a progressive increase in abdominal aortic diameter in both sexes and


Posterior abdominal wall and retroPeritoneum
1088
8
noitCes
Psoas major Psoas minor Lumbar vessels Transversus abdominis posterior to the abdominal aorta. Lumbar arteries arise from its dorsal
aspect, and the third and fourth (and sometimes the second) left
lumbar veins cross behind it to reach the inferior vena cava. The
abdominal aorta may overlap the medial border of the left psoas major
muscle.
On the right, the abdominal aorta is related superiorly to the cisterna
chyli and thoracic duct, the azygos vein and the right crus of the dia-
phragm, which overlaps and separates it from the inferior vena cava and
right coeliac ganglion. Below the second lumbar vertebra, it is closely
applied to the left side of the inferior vena cava. This close relationship
allows the development of an aortocaval fistula, which is a rare com-
plication of aneurysmal disease or trauma. On the left, the aorta is
related superiorly to the left crus of the diaphragm and left coeliac
ganglion. Level with the second lumbar vertebra, it is related to the
fourth part of the duodenum, the left sympathetic trunk, and the infe-
rior mesenteric vein.
Branches
The branches of the aorta are described as anterior, lateral and dorsal
(see Figs 62.8–62.10). The anterior (unpaired) and lateral (paired)
branches are distributed to the viscera, while the dorsal branches supply
the body wall, vertebral column, vertebral canal and its contents. The
aorta terminates by dividing into the right and left common iliac
arteries.
Anterior group
Coeliac trunk
The coeliac trunk is the first anterior branch and arises just below the
aortic hiatus, usually at the level of the vertebral body of T12. It is
1–3 cm long and passes almost horizontally forwards and slightly to
Iliacus Quadratus lumborum the right above the body of the pancreas and splenic vein. In most
individuals, it trifurcates into the left gastric, common hepatic and
splenic arteries. Variations occasionally occur and include a separate
origin of the left gastric artery from the abdominal aorta, one or both
inferior phrenic arteries arising from the coeliac trunk, and the superior


mesenteric artery or one or more of its branches arising in common
with the coeliac trunk (Panagouli et al 2013). Anterior to the coeliac
Fig. 62.7 Bones and deep muscles of the posterior abdominal wall. Left trunk lies the lesser sac. The coeliac plexus surrounds the trunk, sending
psoas major and the diaphragm have been removed. (Adapted from extensions along its branches. On the right lie the right coeliac ganglion,
Drake RL, Vogl AW, Mitchell A (eds), Gray’s Anatomy for Students, right crus of the diaphragm and the caudate lobe of the liver. To the left
2nd ed, Elsevier, Churchill Livingstone. Copyright 2010.) lies the left coeliac ganglion, left crus of the diaphragm and the cardiac
region of the stomach. Rarely, the coeliac trunk can be compressed
by the median arcuate ligament, resulting in visceral ischaemia and
abdominal pain (Loukas et al 2007a).
superior mesenteric artery
the tapering becomes more pronounced (Fleischmann et al 2001). In
The superior mesenteric artery originates from the aorta approximately
the elderly, the abdominal aorta frequently becomes ectatic and tortu-
1–2 cm below the coeliac trunk, at the level of the L1 vertebral body
ous, changing the angle and position of the bifurcation and rotating
(Mirjalili et al 2012b) (Chs 65–66). It lies posterior to the body of the
the origins of the major branches.
pancreas and splenic vein, and is separated from the aorta by the left
Approximately 80% of abdominal aortic aneurysms occur in the
renal vein. It passes forwards and inferiorly, anterior to the uncinate
infrarenal segment of the aorta. Men with atherosclerosis are most at
process of the pancreas and the third part of the duodenum, to enter
risk of developing the condition, particularly from the sixth decade
the root of the small bowel mesentery and supply the midgut. Numer-
onwards (Takayama and Yamanouchi 2013). The high mortality risk
ous anatomical variants have been described (Bergman et al 2014), the
from spontaneous rupture has prompted the development of ultra-


most common being an accessory or replaced right hepatic artery
sound screening programmes to detect occult aneurysms and repair
arising near the origin of the superior mesenteric artery. Present in
them electively. The most common clinical cut-off diameter for the
about 15% of individuals, the accessory or replaced right hepatic artery
presence of an abdominal aortic aneurysm is 3 cm (Needleman 2006,
courses posterior to the portal vein and ascends posterolateral to the
Wegener 1992, Allan 2006, Moeller and Reif 2000). Repair is most
common bile duct (Winston et al 2007).
commonly performed by open surgery or endovascular stenting
(endovascular aneurysm repair). inferior mesenteric artery
The inferior mesenteric artery is smaller than the superior mesenteric
Relations
artery. It arises from the anterior or left anterolateral aspect of the aorta
at about the level of the L3 vertebral body, 3 or 4 cm above the aortic
The upper abdominal aorta is directly related anteriorly to the coeliac bifurcation and posterior to the inferior border of the horizontal part
trunk and its branches, autonomic nerve plexuses and lymphatics. of the duodenum (Ch. 66).
Below the coeliac trunk, the superior mesenteric artery leaves the aorta,
Lateral group
descending anterior to the left renal vein. Anterior to these vessels lies
the body of the pancreas, with the splenic vein on its posterior surface, suprarenal artery
extending obliquely up and to the left (see Fig. 62.8). Further anteriorly, The right and left middle suprarenal arteries arise from each side of the
the lesser sac separates the upper abdominal aorta from the lesser abdominal aorta, level with the superior mesenteric artery. Each passes
omentum, stomach and left lobe of the liver. Below the pancreas, the laterally over the crus of the diaphragm to the suprarenal gland, where
horizontal third part of the duodenum crosses the aorta anteriorly. The it anastomoses with the suprarenal branches of the ipsilateral inferior
most inferior part of the abdominal aorta is covered by the posterior phrenic and renal arteries (Toni et al 1988) (Ch. 71). The right middle


parietal peritoneum and crossed obliquely by the origin of the small suprarenal artery passes behind the inferior vena cava, near the right
bowel mesentery. coeliac ganglion. The left middle suprarenal artery passes close to the
The twelfth thoracic vertebra, the upper four lumbar vertebrae, inter- left coeliac ganglion, splenic artery and the superior border of the
vening intervertebral discs and the anterior longitudinal ligament lie pancreas.


Vascular supply and lymphatic drainage
1089
26
retPaHC
Inferior phrenic veins
Hepatic veins
Oesophageal opening
Inferior vena cava Oesophagus
Left inferior phrenic artery
Right suprarenal gland Coeliac trunk
Right inferior phrenic artery
Right kidney Left renal vein
Left kidney
Superior mesenteric artery
Superior mesenteric vein Subcostal nerve
Iliohypogastric nerve
Transversus abdominis Left ureter
Quadratus lumborum Inferior mesenteric artery
Right gonadal vessels Abdominal aorta
Left gonadal vessels
Ilioinguinal nerve
Iliacus
Psoas minor
Lateral femoral cutaneous nerve Psoas major
Left common iliac artery
Genitofemoral nerve Left common iliac vein
Femoral nerve
Fig. 62.8 The abdominal aorta and inferior vena cava, and their branches. The fasciae, lymphatics and connective tissue have been removed for clarity.
renal artery
Anterior Dorsal Lateral
The renal arteries are two of the largest branches of the abdominal aorta
and arise laterally just below the origin of the superior mesenteric artery
at about the level of the L1 vertebral body (Mirjalili et al 2012b) (Ch.
Inferior 74). When the arteries arise at different cranio-caudal levels, the right
phrenic ostium is more commonly higher than the left. The right renal artery is
Coeliac
Middle longer and passes posterior to the inferior vena cava, right renal vein,
suprarenal head of the pancreas and second part of the duodenum. The left renal
Superior
artery passes behind the left renal vein, the body of the pancreas and
mesenteric Renal
the splenic vein. Variations in the number, origin, course and branching
patterns of the renal arteries are common.
First lumbar
Gonadal artery
L2
The gonadal arteries are two long, slender vessels that arise from the
aorta a little inferior to the renal arteries. Each passes inferolaterally
Second lumbar
under the parietal peritoneum on psoas major to supply the ipsilateral
Inferior Gonadal gonad (Chs 76–77). One or both gonadal arteries may arise from a
mesenteric
renal artery or be double.