Anatomy, Abdomen and Pelvis, Posterior Abdominal Wall Nerves

The abdominal cavity is a closed space that protects the abdominal viscera. The abdominal wall is a physical barrier that prevents injuries of traumatic or microbial etiology. It serves as a scaffold for the abdominal viscera, affixing them for proper anatomical and physiological function, such as increasing intra-abdominal pressure during normal activities (eg, defecation, coughing). The abdominal wall can broadly be subdivided into anterolateral and posterior segments. See Surface Anatomy of the Abdominal Wall. The posterior abdominal wall primarily serves as protection for the retroperitoneal organs (see Posterior Abdominal Wall Arteries). It is mostly musculature contributed by the diaphragm, paraspinal, quadratus lumborum, iliacus, and psoas muscles. The anterolateral abdominal wall consists of 9 layers. From superficial to deep, they are the skin, Camper fascia, Scarpa fascia, external oblique muscle, internal oblique muscle, transversus abdominis muscle, transversalis fascia, extraperitoneal fat, and parietal peritoneum. It is important to note that Camper fascia and Scarpa fascia are usually adherent to each other and form part of the subcutaneous tissue. Each muscle has a layer of fascia, known as investing fascia, on the superficial aspect.