POSTERIOR ABDOMINAL WALL MUSCLES AND NERVES
The diaphragm (principal respiratory muscle) and the psoas major, iliacus, and quadratus lumborum muscles (trunk and lower limb muscles) form the posterior abdominal wall. The ventral rami from the subcostal nerve and lumbar spinal nerves provide somatic innervation to the abdominal wall and lower limb muscles and skin.
The muscles of the posterior abdominal wall are as follows (Figure 11-1):
Muscles and nerves of the posterior abdominal wall.
The somatic nerves of the posterior abdominal wall are the ventral rami of the subcostal and lumbar spinal nerves. These nerves for the most part course between the internal oblique and transverse abdominis muscles (Figure 11-1).
Subcostal nerve (T12). Arises from the T12 ventral ramus.
Motor. Segmentally supplies abdominal body wall muscles (external oblique, internal oblique, transverse abdominis, and rectus abdominis).
Sensory. Anterolateral region of the T12 dermatome.
Iliohypogastric nerve (L1). Arises from the L1 ventral ramus.
Ilioinguinal nerve (L1). Arises from the L1 ventral ramus; after coursing through the body wall, enters the inguinal canal laterally and then exits the superficial inguinal ring to ...