Abdominal wall

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Abdominal wall
Body cavities
Latin	'
Gray's	subject #118 408
System
MeSH	[1]
File:Gray399.png
Diagram of sheath of Rectus above the arcuate line.

The abdominal wall is part of the abdomen and represents the boundaries of the abdominal cavity. The abdominal wall is split into the posterior (back), lateral (sides) and anterior (front) walls.

There is a common set of layers covering and forming all the walls: the deepest being the extraperitoneal fat, the parietal peritoneum, and a layer of fascia which has different names over where it covers (eg transversalis, psoas fascia).

Superficial to these, but not present in the posterior wall are the three layers of muscle, the transversus abdominis (tranvserse abdominal muscle), the internal (obliquus internus) and the external oblique (obliquus externus).

Muscles of the abdominal wall

Henry Gray (1825–1861). Anatomy of the Human Body.

Muscle	Origin and insertion
The obliquus externus (external oblique) muscle is the outermost muscle covering the side of the abdomen. It is broad, flat, and irregularly quadrilateral.	It originates on the lower eight ribs, and then curves down and forward towards its insertion on the outer anterior crest of the ilium and (via the sheath of the rectus abdominis muscle) the midline linea alba.
The obliquus internus (internal oblique) muscle is triangularly shaped and is smaller and thinner than the external oblique muscle that overlies it.	It originates from Poupart's ligament/inguinal ligament and the inner anterior crest of the ilium. The lower two-thirds of it insert, in common with fibers of the external oblique and the underlying transversus abdominis, into the linea alba. The upper third inserts into the lower six ribs.
The transversus abdominis muscle is flat and triangular, with its fibers running horizontally. It lies between the internal oblique and the underlying transversalis fascia.	It originates from Poupart's ligament, the inner lip of the ilium, the lumbar fascia and the inner surface of the cartilages of the six lower ribs. It inserts into the linea alba behind the rectus abdominis.
The rectus abdominis muscles are long and flat. The muscle is crossed by three tendinous intersections called the linae transversae. The rectus abdominis is enclosed in a thick sheath formed, as described above, by fibers from each of the three muscles of the lateral abdominal wall.	They originate at the pubic bone, run up the abdomen on either side of the linea alba, and insert into the cartilages of the fifth, sixth, and seventh ribs.
The pyramidalis muscle is small and triangular. It is located in the lower abdomen in front of the rectus abdominis.	It originates at the pubic bone and is inserted into the linea alba half way up to the umbilicus (belly button).

Layers of anterior abdominal wall

In human anatomy, the layers of the abdominal wall are (from superficial to deep):

• Skin
• Fascia
  • Camper's fascia - fatty superficial layer
  • Scarpa's fascia - deep fibrous layer
• Muscle
  • External oblique muscle
  • Internal oblique muscle
  • Transverse abdominal muscle
• Deep fascia or subserous fascia

Inner surface

The surface contains several ligaments separated by fossae:

Ligament/fold	Remnant of	Lateral fossa	Hernia
median umbilical ligament	urachus	supravesical fossa	-
medial umbilical ligament	umbilical artery	medial inguinal fossa	direct inguinal hernia
lateral umbilical fold	inferior epigastric vessels	lateral inguinal fossa	indirect inguinal hernia

See also

• Peritoneum
• Human abdomen
• Terms for anatomical location

External links

• Memorial University of Newfoundland - Anatomy at MUN digest/abwall
• Norman/Georgetown skel&wallsabd - "Skeleton of the Abdomen", Wesley Norman, PhD, DSc
• MeSH Abdominal+Wall
• Anterolateral Abdominal Wall - University of Edinburgh Faculty of Medicine
• Muscles of the Anterior Abdominal Wall - University of Arkansas