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Practical Anatomy
Dr. Firas M. Ghazi
Anterior Abdominal Wall
Lab Check List
Objectives: By the end of this lab students should be able to
Identify the bones of the abdominal region
Describe various landmarks of these bones
Distinguish the layers of superficial fascia and its extensions
Recognize the muscles of anterior abdominal wall
Define the rectus sheath (location, formation and content)
Discuss the boundaries and content of the inguinal canal
List the nerves supplying anterior abdominal wall and their corresponding dermatomes
A) Bones of the abdominal region
 Hip bone
 Ilium:
 Anterior superior iliac spine (ASIS)
 Iliac crest and tubercle
 Pubis
 Superior and Inferior rami
 Body (Pubic tubercle and crest)
 Symphesis pubis
 Ischium
 Five Lumber vertebra
 Lower eight Ribs
B) Superficial fascia
 Note: The anterior abdominal wall is made up of skin, superficial fascia, deep fascia, muscles,
extraperitoneal fascia, and parietal peritoneum.
 Fatty layer (fascia of Camper)
 Superficial, Thick
 Continuous with superficial fat over the rest of the body
 Membranous layer Scarpa’s fascia
 Deep, Thin
 Laterally: becomes continuous with superficial fascia of the back
 Superiorly: becomes continuous with superficial fascia of the thorax
 Inferiorly (lateral to midline): reaches the front of thigh to fuse with fascia lata
 Inferiorly (in the midline): it forms a special fascia of external genitalia (refer to lecture)
C) Muscles of Anterolateral abdominal wall
 Linea alba:
 A fibrous band at the midline
 Extends between xiphoid process and symphysis pubis
 Formed by fusion of aponeuroses of the three flat abdominal muscles of the two sides
Further assistance on:
University website:
Facebook page: Anatomy For Babylon Medical Students
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Practical Anatomy
Dr. Firas M. Ghazi
 External oblique
 Broad thin sheet with aponeurosis
 Origin: outer surfaces of the lower eight ribs (Rs 5-12)
 Insertion: xiphoid process, linea Alba, pubic crest and tubercle, ASIS, and the anterior half
of the iliac crest
 Fiber direction: downward and forward
 Inguinal ligament: the lower border of muscle (aponeurosis) between ASIS and pubic
 Posterior free border: made by most posterior fibers between rib and the iliac crest
 Superficial inguinal ring: a defect in the aponeurosis of the muscle immediately above and
medial to pubic tubercle
 Internal oblique
 Broad, thin, sheet, deep to external oblique
 Origin: lumbar fascia, anterior two thirds of the iliac crest, and the lateral two thirds of the
inguinal ligament
 Insertion: lower three ribs and costal cartilages, xiphoid process, the linea alba, and the
symphysis pubis
 Fiber direction: upward and forward (at right angles to those of external oblique)
 Lower free border: formed by lowest fibers of the muscle arching between inguinal
ligament and pubic crest
 Transversus
 Broad, thin sheet, deep to internal oblique
 Origin: lower six costal cartilages (inner surface), lumbar fascia, anterior two thirds of iliac
crest, and lateral third of inguinal ligament
 Insertion: It is inserted into the xiphoid process, the linea alba, and the symphysis
 Fiber direction: horizontally forward
 Conjoint tendon: a tendon formed by the lowest fibers of transversus and internal oblique
joining together near their insertion. It is fixed to pubic crest and pectineal line
 Fascia Transversalis
 A thin layer of fascia lines the transversus muscle
 Part of a fascia that line the abdominal cavity
 Rectus sheath
 A long fibrous sheath
 Formation: aponeurosis of internal oblique muscle split at the mid-clavicular line to
enclose the rectus abdominus muscle (longitudinal muscle of anterior abdominal wall)
 Arrangement:
a) Above ASIS:
 Anterior layer: external oblique & anterior layer of internal oblique aponeurosis
 Posterior layer: posterior layer of internal oblique & transversus aponeurosis
Further assistance on:
University website:
Facebook page: Anatomy For Babylon Medical Students
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Practical Anatomy
Dr. Firas M. Ghazi
b) Below ASIS:
 Anterior layer: aponeurosis of all three muscles
 Posterior layer: absent
 Arcuate line: free, curved lower border of the posterior layer at the level of ASIS
 Separated from its fellow by linea alba.
 Note: the posterior wall of rectus sheath is not attached to the rectus abdominis. This
allow sideway retraction of the muscle during surgical operations
 Content:
1. Rectus abdominis
2. Pyramidalis (if present)
3. Lower six thoracic nerves
4. Superior and inferior epigastric vessels:
 Anastomose with each other within the sheath
 Superior epigastric artery:
 Terminal branches of the internal thoracic artery
 Enters the rectus sheath between sternal and costal origins of diaphragm
 It descends behind the rectus muscle
 Inferior epigastric vessels
 Branch off the external iliac artery just above the inguinal ligament
 Enter the rectus sheath superficial (anterior) to arcuate line
 Ascends behind the rectus muscle
 Rectus abdominis
 Long, extends along the whole length of the anterior abdominal wall near to midline, being
separated from its fellow by linea alba
 Origin: symphysis pubis and pubic crest
 Insertion: 5th - 7th costal cartilages, xiphoid process
 Fiber direction: vertically downward
 Linea semilunaris: curved ridge formed by its lateral margin, extends from the tip of the
ninth costal cartilage to the pubic tubercle.
 Tendinous intersections: three transverse tendinous structures divide the muscle into
distinct segments
 Above ASIS: enclosed between the layers of the rectus sheath
 Below ASIS: in contact with the fascia transversalis
 Pyramidalis
 Often absent
 Lies in front of the lower part of the rectus abdominis
 From pubis to linea alba
Further assistance on:
University website:
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Practical Anatomy
Dr. Firas M. Ghazi
D) Inguinal canal
 Definition: Oblique canal through the lower part of anterior abdominal wall, parallel to and
immediately above the inguinal ligament, Allow structures to pass in and out between the
abdominal cavity and external genitalia
 Length in adult: 4 cm
 Openings:
1. Deep inguinal ring:
 Opening in the fascia transversalis
 Site: Above the inguinal ligament midway between ASIS and symphysis pubis
 Note: Inferior epigastric vessels ascends medial to the ring
2. Superficial inguinal ring
 Inguinal ligament
 Lacunar ligament
 Pectineal ligament
E) Nerves of the abdominal wall
 Note: refer to Snell clinical anatomy by regions 9th edition (Figure 4.16 page 125) for nerve
distribution and dermatomes of anterior abdominal wall
 Nerves are anterior rami of:
1. T7-T11: intercostal nerves
2. T12: subcostal nerve
3. L1: first lumbar nerves (iliohypogastric and ilioinguinal)
 Important dermatomes:
1. T7: epigastrium over the xiphoid process
2. T10 includes the umbilicus
3. L1 lies just above the inguinal ligament and symphysis pubis.
 Course:
 Run forward in between internal oblique and transversus
 T5-12 enter the rectus sheath
 Iliohypogastric nerve run just above the inguinal canal and the superficial inguinal ring
 Ilioinguinal nerve run along the inguinal canal and emerges through the superficial
inguinal ring
 Distribution:
 Skin, muscles, and the parietal peritoneum of anterior abdominal wall
 Pyramidalis supplied by T12 only
Further assistance on:
University website:
Facebook page: Anatomy For Babylon Medical Students
Page 4