Innervation Of The Anterior Abdominal Wall

The nerves of the anterior abdominal wall are the ventral rami of the T6-L1 spinal nerves. These nerves course downward and anteriorly between the internal oblique and the transverse abdominis muscles. They segmentally supply cutaneous innervation to the skin and parietal peritoneum and are the motor supply to the anterolateral abdominal wall muscles. The lower intercostal nerves and the subcostal nerve pierce the deep layer of the rectus sheath and course through to the skin to become the anterior cutaneous nerves of the abdomen. The first lumbar nerve bifurcates into the iliohypogastric and ilioinguinal nerves, which do not enter the rectus sheath. Instead, the iliohypogastric nerve pierces the external oblique aponeurosis superior to the superficial inguinal ring, whereas the ilioinguinal nerve passes through the inguinal canal to emerge through the superficial inguinal ring.

VWhen the appendix becomes inflamed, the visceral sensory fibers are stimulated. These fibers enter the spinal cord with the sympathetic fibers at spinal cord level T10. The pain is referred to the dermatome of T10, which is in the umbilical region. The visceral pain is diffuse, not focal; each time a peristaltic wave passes through the ileocecal region, the pain recurs. When the parietal peritoneum eventually becomes inflammed, the somatic pain is sharp and focal. This is recognized by a diagnostic test for acute appendicitis: push on McBurney's point. The knee and hip on the inflammed side flex abruptly. Although appendicitis is common, other disorders of the bowel and pelvis may present with similar symptoms. ▼

Left subclavian a.

Internal thoracic a. and v.

Internal oblique m Rectus abdominis m External oblique m. Transversus abdominis m. Inferior epigastric a. and v.

Superficial circumflex iliac a. and v.

Superficial epigastric a. and v.

Internal thoracic a.

Superior epigastric a.

Left subclavian a.

Internal thoracic a. and v.

Superficial circumflex iliac a. and v.

Superficial epigastric a. and v.

Internal thoracic a.

Superior epigastric a.

Superficial circumflex iliac a.

Superficial epigastric a.

Inferior epigastric a.

Femoral a.

Figure 7-3: Neurovascular structures of the anterior abdominal wall. The left side of the figure shows a step dissection detailing the location of the neurovascular structures. The right side of the figure shows a schematic of arterial supply.

Inferior epigastric a.

Superficial circumflex iliac a.

Superficial epigastric a.

Femoral a.

Figure 7-3: Neurovascular structures of the anterior abdominal wall. The left side of the figure shows a step dissection detailing the location of the neurovascular structures. The right side of the figure shows a schematic of arterial supply.

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