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14 Abdominal Wall Anatomy and Inguinal Anatomy ppt.pptx
1. Abdominal Wall Anatomy
and
Inguinal Region
Presenter : Dr Gobena Mormata (PGY1)
Moderator: Dr Abebe (Consultant General and Hepatobiliary surgeon)
3/26/2024 1
3. Objectives
• To understand anatomy of abdominal wall and clinical correlation.
• To understand anatomy of inguinal region and clinical correlation.
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4. Introduction
The abdomen is the part of the trunk between the thorax and the
pelvis.
It is a flexible, dynamic container, housing most of the organs of the
alimentary system and part of the urogenital system.
Containment of the abdominal organs and their contents is provided by
the diaphragm superiorly, and
the muscles of the pelvis inferiorly.
Musculo-aponeurotic walls anterolaterally
Lumbar bones, 12th rib, sacrum and iliac crest
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5. Abdominal wall
• The abdominal wall is a dynamic, multi-layered, Musculo-
aponeurotic
• It provides structure, protection, and support for abdominal and
retroperitoneal structures and
• Knowledge of its specific anatomic features is required for
management of abdominal wall diseases or during entry into the
peritoneal cavity.
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8. Cont…
Although the abdominal wall is
continuous, it is subdivided into the:
Anterior wall, right and left lateral
walls, and posterior wall for
descriptive purposes.
Anterolateral vs Posterior
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9. ANTEROLATERAL ABDOMINAL WALL
is bounded superiorly by the
cartilages of the 7th–10th ribs and the
xiphoid process of the sternum, and
inferiorly by the inguinal ligament and
the superior margins of the
anterolateral aspects of the pelvic
girdle (iliac crests, pubic crests, and
pubic symphysis)
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10. Cont…
Consists of 9 layers :
Skin
Subcutaneous tissue (superficial
fascia)
Muscles and their aponeuroses
and investing fascia
Deep fascia
Extraperitoneal fat
Parietal peritoneum
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It is a major site of fat
storage
11. Fascia of the Anterolateral Abdominal Wall
It is a major site of fat storage.
Superior to the umbilicus, the subcutaneous tissue is consistent with
that found in most regions.
Inferior to the umbilicus, two layers: the superficial fatty layer
(Camper fascia) and the deep membranous layer (Scarpa fascia) of
subcutaneous tissue.
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12. Cont…
Superficial, intermediate, and
deep layers of investing fascia
The investing fascia here are
extremely thin, being represented
mostly by the epimysium
superficial to or between
muscles.
Endo abdominal fascia.
Transversalis fascia.
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13. Muscles of Anterolateral Abdominal Wall
There are five (bilaterally paired)
muscles in the anterolateral
abdominal wall :
three flat muscles
two vertical muscles.
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14. EXTERNAL OBLIQUE MUSCLE
The largest and most superficial of the three flat
anterolateral abdominal muscles.
• Origin- External surfaces of 5th -12th ribs
• Insertion -Linea alba, pubic tubercle, and anterior
half of iliac crest
• Vascular supply- lower posterior intercostal and
subcostal arteries above and the deep circumflex
iliac artery below.
• Nerve supply -Thoraco-abdominal
nerves (T7–T11 spinal nerves) and subcostal
nerves
• Action - Compresses and supports abdominal
viscera flexes and rotates trunk.
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15. Inguinal ligament
• Is the thick lower border of the aponeurosis of
external oblique that stretches between the
anterior superior iliac spine and the pubic
tubercle
• Its medial half is curled in on itself, forming
the gutter-like ‘floor’ of the inguinal canal.
• Lower border, is fused with the fascia lata,
laterally, fused with the iliopsoas fascia.
• Lacunar ligament – pectineal line
• Fibres from both sides decussate in the linea
alba.
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16. INTERNAL OBLIQUE MUSCLE
• Origin- Thoracolumbar fascia, anterior two thirds
of iliac crest, and connective tissue deep to lateral
third of inguinal ligament
• Insertion- Inferior borders of 10th -12th ribs,
Linea alba, and pecten pubis via conjoint tendon
• Blood supply-lower posterior intercostal and
subcostal arteries, the inferior
epigastric artery, and the deep circumflex iliac
artery.
• Nerve supply- Thoraco-abdominal nerves
(anterior rami of T6–T12 spinal nerves) and first
lumbar nerves.
• Action- Compresses and supports abdominal
viscera flexes and rotates trunk.
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17. TRANSVERSUS ABDOMINIS MUSCLE
• Origin- Internal surfaces of 7th –12th costal
cartilages, thoracolumbar fascia, iliac crest, and
connective tissue deep to lateral third of inguinal
ligament
• Insertion- Linea alba with aponeurosis of internal
oblique, pubic crest, and pecten pubis via conjoint
tendon
• Vascular supply- lower posterior intercostal
and subcostal arteries, the superior and inferior
epigastric arteries, the superficial and deep
circumflex iliac arteries and the posterior lumbar
arteries.
• Nerve supply- Thoraco-abdominal nerves
(anterior rami of T6–T12 spinal nerves) and first
lumbar nerves.
• Action- Compresses and supports abdominal viscera.
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18. Conjoint tendon
• Formed from the lower fibres of internal
oblique and the lower part of the
aponeurosis of transversus abdominis.
• Attached to the pubic crest and extends to
a variable extent along the pectineal line.
• Descends behind the superficial inguinal
ring and strengthen the medial portion of
the posterior wall of the inguinal canal.
• Medially, the upper fibres of the tendon
fuse with the anterior wall of the rectus
sheath, and laterally.
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Clinical significance
Weakening of conjoint tendon can
precipitate a direct inguinal hernia
19. Cont…
Neurovascular plane
Between the internal oblique and the
transversus abdominis muscles.
Contains the nerves and arteries supplying
the anterolateral abdominal wall.
In the anterior part of the abdominal wall,
the nerves and vessels leave the
neurovascular plane and lie mostly in the
subcutaneous tissue.
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20. RECTUS ABDOMINIS MUSCLE
• Long, broad, strap-like muscle principal vertical
muscle of the anterior abdominal wall
• Origin- Pubic symphysis and pubic crest
• Insertion- Xiphoid process and 5th – 7th costal
cartilages
• Vascular supply- superior and inferior
epigastric arteries. Small terminal branches from the lower three
posterior intercostal arteries, the subcostal artery, the lumbar arteries and the
deep circumflex iliac artery
• Nerve supply- Thoraco-abdominal nerves
(anterior rami of T6–T12 spinal nerves)
• Action- Flexes trunk (lumbar vertebrae) and
compresses abdominal viscera, stabilizes and
controls tilt of pelvis (antilordosis)
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6 packs
Diastasis recti
Partial /complete
separation
21. PYRAMIDALIS
The pyramidalis is a small, insignificant
triangular muscle that is absent in
approximately 20% of people.
Origin - anterosuperior margin of the pubis and
to ligamentous fibers in front of the symphysis.
Insertion - ends in a pointed apex that is attached
medially to the linea alba.
Innervation– anterior rami of T12/L1
Action - contributes to tensing the lower linea
alba but is of doubtful physiological significance.
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24. RECTUS SHEATH, LINEAALBA, AND UMBILICAL RING
The rectus sheath is the strong, incomplete fibrous compartment
formed by the decussation and interweaving of the aponeuroses of the
flat abdominal muscles. Contains :
the rectus abdominis and pyramidalis muscles.
the superior and inferior epigastric arteries and veins,
lymphatic vessels, and
distal portions of the thoraco-abdominal nerves (abdominal portions
of the anterior rami of spinal nerves T7–T12)
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27. Preperitoneal Space and Peritoneum
Lies between the transversalis fascia and parietal peritoneum and contains
adipose and areolar tissue. Coursing through the preperitoneal space are the
following:
Inferior epigastric artery and vein
Medial umbilical ligaments, which are the vestiges of the fetal umbilical
arteries
Median umbilical ligament, which is a midline fibrous remnant of the fetal
allantoic stalk or urachus
Falciform ligament of the liver, extending from the umbilicus to the liver
used for placing prostheses when repairing inguinal hernias .
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28. Internal Surface of Anterolateral Abdominal Wall
• The laparoscopic approach
• Intraperitoneal points of reference are
the five peritoneal folds, bladder,
inferior epigastric vessels, and psoas
muscle
• Two potential spaces exist within the
preperitoneum
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30. FUNCTIONS AND ACTIONS OF ANTEROLATERAL ABDOMINAL
MUSCLES
Form a strong expandable support for the anterolateral abdominal wall.
Support the abdominal viscera and protect them from most injuries
Compress the abdominal contents to maintain or increase the intra-abdominal
pressure and, in so doing, oppose the diaphragm (increased intra-abdominal
pressure facilitates expulsion).
Move the trunk and help to maintain posture.
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36. Inguinal Region
The inguinal region (groin) extends between the ASIS and pubic
tubercle.
It is an important area anatomically and clinically:
anatomically because it is a region where structures exit and enter the
abdominal cavity, and
clinically because the pathways of exit and entrance are potential sites
of herniation.
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38. INGUINAL CANAL
Is formed in relation to the relocation of the testis during fetal development.
An oblique passage, cone shaped 4-6 cm long, directed inferomedially
through the inferior part of the anterolateral abdominal wall.
• Begins on the posterior abdominal wall, where the spermatic cord passes
through the deep (internal) inguinal ring (a hiatus in the transversalis fascia)
• Concludes medially at the superficial (external) inguinal ring, the point at
which the spermatic cord crosses a defect in the external oblique
aponeurosis
• Lies parallel and superior to the medial half of the inguinal ligament
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44. Cont…
• Inguinal ligament
• Lacunar ligament (of gimbernat)
• Pectineal ligament (of cooper).
• Some of the more superior fibers fan
upward, bypassing the pubic tubercle
and crossing the linea alba.
• These fibers form the reflected
inguinal ligament
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45. Cont…
Iliopubic tract
• parallel and posterior (deep) to the
inguinal ligament
• Reinforces the posterior wall and floor
of the inguinal canal
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46. Cont…
The inguinal ligament and ilio-pubic tract,
constitute a bilaminar anterior (flexor)
retinaculum of the hip joint.
sub inguinal space, through which pass the
flexors of the hip and neurovascular
structures serving much of the lower limb.
• Myopectineal orifice
• Weak area in the groin where posterior layer
is not protected by overlying muscle
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MPO boarders
Above- arching fibers of IO & TA, its fascia
Below- Coopers ligament
Medially- Rectus abdominis Muscle and its Rectus
sheath
Laterally- Ileo psoas Muscles
48. Hessel Bach's triangle/ Inguinal triangle, Femoral ring
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TRIANGLE OF DOOM
TRIANGLE OF PAIN
CIRCLE OF DEATH
49. Posterior abdominal wall
The posterior abdominal wall is mainly composed of the:
Five lumbar vertebrae and associated IV discs (centrally).
Posterior abdominal wall muscles, including the psoas, quadratus
lumborum, iliacus, transversus abdominis, and oblique muscles (laterally).
Diaphragm, which contributes to the superior part of the posterior wall.
Fascia, including the thoracolumbar fascia.
Lumbar plexus, composed of the anterior rami of lumbar spinal nerves.
Fat, nerves, vessels (e.g., aorta and IVC), and lymph nodes.
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51. Fascia of Posterior Abdominal Wall
• Psoas Fascia
• Thoracolumbar Fascia: has two parts; thoracic part(thin) and lumbar
part which is thick , three layers, extends b/n 12th rib and iliac crest,
attached medially to vertebral column, laterally to TA & IO muscles
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52. Muscles of Posterior Abdominal Wall
The main paired muscles in the posterior abdominal wall are the:
Psoas major: passing inferolaterally.
Iliacus: lying along the lateral sides of the inferior part of the psoas
major.
Quadratus lumborum: lying adjacent to the transverse processes of the
lumbar vertebrae and lateral to superior parts of the psoas major.
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54. Diaphragm
Double-domed, musculotendinous
Chief muscle of inspiration
Muscular part
Descriptive purposes it is divided into
three parts, based on the peripheral
attachments:
Sternal part
Costal part
Lumbar part
trifoliate central aponeurotic part,
the central tendon
•
55. Nerves of Posterior Abdominal Wall
Subcostal nerves (anterior rami of T12)
Lumbar spinal nerves (L1–L5)
Lumbar plexus of nerves (anterior rami of L1 through L4 nerves)
Femoral nerve (L2–L4)
Obturator nerve (L2–L4)
Lumbosacral trunk (L4, L5)
Ilio-inguinal and iliohypogastric nerves (L1)
Genitofemoral nerve (L1, L2)
Lateral cutaneous nerve of the thigh/lateral femoral cutaneous nerve (L2, L3)
Accessory obturator nerve (L3, L4)
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58. Cont…
The veins of the posterior abdominal wall are tributaries of the IVC,
except for the left testicular or ovarian vein, which enters the left renal
vein instead of entering the IVC.
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59. LYMPHATIC VESSELS AND LYMPH NODES OF POSTERIOR ABDOMINAL WALL
All the lymphatic drainage from the lower half of the body (deep
lymphatic drainage inferior to the level of the diaphragm and all
superficial drainage inferior to the level of the umbilicus) converges in
the abdomen to enter the beginning of the thoracic duct.
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Collateral Routes for
Abdominopelvic
Venous Blood
1. superior and inferior
epigastric veins
2. thoraco-epigastric
vein
3. epidural venous
plexus
60. References
• Moore, clinically oriented anatomy, 7th edition
• Susan Standring - Gray's Anatomy_ The Anatomical Basis of Clinical
Practice-Elsevier (c2016), 41th edition
• Frank H. Netter MD - Atlas of Human Anatomy_ Including Student
Consult-Elsevier (2018), 7th edition
• Sabiston Textbook of Surgery The Biological Basis of Modern surgical
practice, 20th edition
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but due to indistinct between anterior and posterior classified as Anterolateral vs Posterior
The skin attaches loosely to the subcutaneous tissue, except at the umbilicus, where it adheres firmly.
Superior to the umbilicus, the subcutaneous tissue is consistent with that found in most regions. Inferior to the umbilicus, the deepest part of the subcutaneous tissue is reinforced by many elastic and collagen fi bers, so it has two layers: the superfi cial fatty layer (Camper fascia) and the deep membranous layer (Scarpa fascia) of subcutaneous tissue.
The investing fascias here are extremely thin, being represented mostly by the epimysium (outer fibrous connective tissue layer surrounding all muscles—see Introduction) superfi cial to or between muscles.
The glistening lining of the abdominal cavity, the parietal peritoneum, is formed by a single layer of epithelial cells and supporting connective tissue. The parietal peritoneum is internal to the transversalis fascia and is separated from it by a variable amount of extraperitoneal fat.
All three flat muscles are continued anteriorly and medially as strong, sheet-like aponeuroses (Fig. 2.6A). Between the midclavicular line (MCL) and the midline, the aponeuroses form the tough, aponeurotic, tendinous rectus sheath enclosing the rectus abdominis muscle (Fig. 2.6B). The aponeuroses then interweave with their fellows of the opposite side, forming a midline raphe (G. rhaphe, suture, seam), the linea alba (L. white line), which extends from the xiphoid process to the pubic symphysis. The decussation and interweaving of the aponeurotic fibers here is not only between right and left sides but also between superficial and intermediate and intermediate and deep layers.
In contrast to the two deeper layers, the external oblique does not originate posteriorly from the thoracolumbar fascia; its posterior most fi bers (the thickest part of the muscle) have a free edge where they span between its costal origin and the iliac crest
At its lower border, it is fused with the fascia lata. Laterally, it is fused with the iliopsoas fascia (Lytle 1974). At the medial end of the inguinal ligament, near its site of attachment to the pubic tubercle, some of its fibres extend posteriorly and laterally to attach to the pectineal line, forming the triangular, shelf-like lacunar ligament. Other fibres pass upwards and medially behind the superficial inguinal ring and external oblique aponeurosis to join the rectus sheath and linea alba; these constitute the reflected part of the inguinal ligament (Tubbs et al 2009). Fibres from both sides decussate in the linea alba.
The rectus abdominis is three times as wide superiorly as inferiorly; it is broad and thin superiorly and narrow and thick inferiorly.
The rectus muscle is anchored transversely by attachment to the anterior layer of the rectus sheath at three or more tendinous intersections
The pyramidalis is a small, insignificant triangular muscle that is absent in approximately 20% of people. It lies anterior to the inferior part of the rectus abdominis and attaches to the anterior surface of the pubis and the anterior pubic ligament. It ends in the linea alba, which is especially thickened for a variable distance superior to the pubic symphysis. The pyram idalis tenses the linea alba. When present, surgeons use the attachment of the pyramidalis to the linea alba as a landmark for median abdominal incision (Skandalakis et al., 2009)
Throughout the length of the sheath, the fibers of the anterior and posterior layers of the sheath interlace in the anterior median line to form the complex Linea alba.
A crescentic arcuate line demarcates the transition between the aponeurotic posterior wall of the sheath covering the superior three quarters of the rectus and the transversalis fascia covering the inferior quarter.
At its middle, underlying the umbilicus, the Linea alba contains the umbilical ring, a defect in the Linea alba through which the fetal umbilical vessels passed to and from the umbilical cord and placenta.
An anterolateral part of this potential space between the transversalis fascia and the parietal peritoneum (space of Bogros) is used for placing prostheses (Gore-Tex mesh, for example) when repairing inguinal hernias (Skandalakis et al., 1996)
The most medial aspect of the preperitoneal space, that which lies superior to the bladder, is known as the space of Retzius.
The internal (posterior) surface of the anterolateral abdominal wall is covered with transversalis fascia, a variable amount of extraperitoneal fat, and parietal peritoneum
triangle of doom, the triangle of pain, and the circle of death
The remnant of the embryonic left umbilical vein forms the round ligament of the liver. The obliterated umbilical arteries form the medial umbilical ligaments on the undersurface of the anterior abdominal wall and are covered by the medial umbilical folds. The partially obliterated remains of the urachus persist as the median umbilical ligament and fold. Both congenital and acquired umbilical hernias are common; most childhood umbilical hernias close spontaneously and do not require surgical repair. The umbilicus is the most common site for laparoscopic access to the peritoneal cavity.
Reversal of Venous Flow and Collateral Pathways of Superfi cial Abdominal Veins
The lymphatic vessels from the liver course along the ligamentum teres to the umbilicus to communicate with the lymphatics of the anterior abdominal wall. It is from this pathway that carcinoma in the liver may spread to involve the anterior abdominal wall at the umbilicus (Sister Mary Joseph node or nodule). it is a palpable nodule in the region of the umbilicus representing metastatic abdominal or pelvic cancer.
The inguinal region (groin) extends between the ASIS and pubic tubercle. It is an important area anatomically and clinically: anatomically because it is a region where structures exit and enter the abdominal cavity, and clinically because the pathways of exit and entrance are potential sites of herniation.
The iliopubic tract is an aponeurotic band that begins at the anterior superior iliac spine and inserts into Cooper’s ligament from above. It forms on the deep inferior margin of the transversus abdominis and transversalis fascia. The lacunar ligament, or ligament of Gimbernat, is the triangular fanning of the inguinal ligament as it joins the pubic tubercle. Cooper’s (pectineal) ligament is the lateral portion of the lacunar ligament that is fused to the periosteum of thepubic tubercle. The conjoined tendon is commonly described as the fusion of the inferior fibers of the internal oblique and transversus abdominis aponeurosis at the point where they insert on the pubic tubercle.
INGUINAL CANAL is formed in relation to the relocation of the testis during fetal development. The inguinal canal in adults is an oblique passage, approximately 4 cm long, directed inferomedially through the inferior part of the anterolateral abdominal wall. It lies parallel and superior to the medial half of the inguinal ligament (see Figs. 2.14 and 2.15). The main occupant of the inguinal canal is the spermatic cord in males and the round ligament of the uterus in females. These are functionally and developmentally distinct structures that occur in the same location. The inguinal canal also contains blood and lymphatic vessels and the ilio-inguinal nerve in both sexes.
The borders of the triangle are the inguinal ligament inferiorly, the lateral edge of rectus sheath medially, and the inferior epigastric vessels superolaterally.
The triangle of pain is bound by the iliopubic tract, testicular vessels, and the peritoneal fold.
The Triangle of Doom is an anatomical triangle defined by the vas deferens medially, spermatic vessels laterally and peritoneal fold inferiorly.[1] This triangle contains external iliac artery and vein, the deep circumflex iliac vein, the genital branch of genitofemoral nerve and hidden by fascia, the femoral nerve.
The posterior abdominal wall (Figs. 2.95–2.97) is mainly composed of the:
Five lumbar vertebrae and associated IV discs (centrally). • Posterior abdominal wall muscles, including the psoas, quadratus lumborum, iliacus, transversus abdominis, and oblique muscles (laterally). • Diaphragm, which contributes to the superior part of the posterior wall. • Fascia, including the thoracolumbar fascia. • Lumbar plexus, composed of the anterior rami of lumbar spinal nerves. • Fat, nerves, vessels (e.g., aorta and IVC), and lymph nodes.
The main paired muscles in the posterior abdominal wall (Fig. 2.96; Table 2.14) are the: • Psoas major: passing inferolaterally. • Iliacus: lying along the lateral sides of the inferior part of the psoas major. • Quadratus lumborum: lying adjacent to the transverse processes of the lumbar vertebrae and lateral to superior parts of the psoas major. The attachments, nerve supply, and main actions of these muscles are summarized in Table 2.14.
This nerve network is composed of the anterior rami of L1 through L4 nerves. The following nerves are branches of the lumbar plexus; the three largest are listed first:
The femoral nerve (L2–L4) emerges from the lateral border of the psoas major and innervates the iliacus and passes deep to the inguinal ligament/iliopubic tract to the anterior thigh, supplying the fl exors of the hip and extensors of the knee. • The obturator nerve (L2–L4) emerges from the medial border of the psoas major and passes into the lesser pelvis, passing inferior to the superior pubic ramus (through the obturator foramen) to the medial thigh, supplying the adductor muscles. • The lumbosacral trunk (L4, L5) passes over the ala (wing) of the sacrum and descends into the pelvis to participate in the formation of the sacral plexus with the anterior rami of S1–S4 nerves. • The ilio-inguinal and iliohypogastric nerves (L1) arise from the anterior ramus of L1, entering the abdomen posterior to the medial arcuate ligament and passing inferolaterally, anterior to the quadratus lumborum. They run superior and parallel to the iliac crest, piercing the transversus abdominis near the ASIS. They then pass through the internal and external obliques to supply the abdominal muscles and skin of the inguinal and pubic regions. The division of the L1 anterior ramus may occur as far distally as the ASIS, so that often only one nerve (L1) crosses the posterior abdominal wall instead of two. • The genitofemoral nerve (L1, L2) pierces the psoas major and runs inferiorly on its anterior surface, deep to the psoas fascia; it divides lateral to the common and external iliac arteries into femoral and genital branches. • The lateral cutaneous nerve of the thigh, or lateral femoral cutaneous nerve (L2, L3), runs inferolaterally on the iliacus and enters the thigh deep to the inguinal ligament/ iliopubic tract, just medial to the ASIS; it supplies skin on the anterolateral surface of the thigh. • An accessory obturator nerve (L3, L4) is present almost 10% of the time. It parallels the medial border of the psoas, anterior to the obturator nerve, crossing superior to the superior pubic ramus in close proximity to the femoral vein.
Components of both the somatic and autonomic (visceral) nervous systems are associated with the posterior abdominal wall
Lumbosacral triangle is formed only by superior and inferior fascia of diaphragm, it lacks muscles
Three collateral routes, formed by valveless veins of the trunk, are available for venous blood to return to the heart when the IVC is obstructed or ligated.
Two of these routes (one involving the superior and inferior epigastric veins, and another involving the thoraco-epigastric
The third collateral route involves the epidural venous plexus inside the vertebral column (illustrated and discussed in Chapter 4—Back), which communicates with the lumbar veins of the inferior caval system, and the tributaries of the azygos system of veins, which is part of the superior caval system.
