Anatomy - Change of an abdominal vacuum dressing in an open abdomen

The large area covering the anterior abdominal wall from the xiphoid process or the costal arches to the pelvic bones has a typical layered structure: beneath the skin and subcutaneous fat tissue, there are superficial fasciae, muscles and their fasciae, then an extraperitoneal fascia and the parietal peritoneum.

Especially in the anterior wall below the navel, the otherwise typical single-layered superficial fascia transitions into a two-layered structure (Panniculus adiposus abdominis) consisting of a superficial fat-rich layer (Camper's fascia) and a deeper membranous layer (Scarpa's fascia). The 5 abdominal muscles consist of:
3 oblique muscles (1. External oblique muscle, 2. Internal oblique muscle, and 3. Transverse abdominal muscle)
2 straight muscles (4. Rectus abdominis muscle and the inconstant 5. Pyramidalis muscle).

• external muscle
  located immediately beneath the superficial fascia, it runs caudomedially to the large aponeurosis, both sides merge centrally to form the linea alba. Its lower edge forms the inguinal ligament from the anterior superior iliac spine to the pubic tubercle, which in turn medially branches into the lacunar ligament and the pectineal ligament (Cooper's ligament).
• middle muscle
  fibers run craniomedially merging with fibers from 1. to the linea alba.
• innermost muscle
  transversely running fibers, also radiating into the linea alba.

Each of the three oblique abdominal muscles has a thin, own fascia on its front and back surface, 3. on its inner side the strong transversalis fascia. This lines the abdominal cavity and transitions cranially into the diaphragmatic fascia and dorsally into the thoracolumbar fascia. Caudally it is attached to the iliac crest and transitions into the endopelvic fascia.

Long straight paired abdominal muscle, interrupted by 3 – 4 transverse tendinous intersections ("six-pack").

Triangular rudimentary muscle caudal and ventral to 4. between the pubic bone and linea alba.

Muscles 4 and 5 are enveloped by the rectus sheath, which is formed by the three oblique abdominal muscles 1 to 3. 4 is completely enveloped by it in its upper ¾, while in the lower ¼ below the arcuate line, it is only covered in front, with the posterior surface of 4 only showing the transversalis fascia and the peritoneum. In the upper ¾, the anterior layer of the rectus sheath is formed by 1 and half by 2, the posterior layer half by 2 and 3.

Between the transversalis fascia and the peritoneum is the extraperitoneal space, which can vary in extent depending on the location. In the retroperitoneum, the retroperitoneal abdominal organs are located here. On the anterior abdominal wall, it is repeatedly referred to as the preperitoneal space (e.g., at the internal inguinal ring).

The peritoneum (parietal serosa) forms the completely closed peritoneal cavity (exception: opening of the tube in women) and transitions as visceral peritoneum onto the intraperitoneal organs. Below the navel, it forms three folds:
the unpaired median umbilical fold (obliterated urachus/urinary duct)
the paired medial umbilical fold (former umbilical artery)
the paired lateral umbilical fold (inferior epigastric vessels)

The anterior abdominal wall is innervated by the anterior rami of the spinal nerves Th7 to Th11, Th12 (subcostal nerve), and L1 (iliohypogastric nerve and ilioinguinal nerve).

Its superficial blood supply is cranially from the internal thoracic artery (→ musculophrenic artery), in the lower part from the superficial epigastric artery and the superficial circumflex iliac artery (both from the femoral artery). The deep blood supply comes cranially from the superior epigastric artery (← internal thoracic artery), laterally from intercostal vessels, and caudally from the inferior epigastric artery and the deep circumflex iliac artery (both from the external iliac artery). Venous drainage occurs via veins of the same name.