The anterior abdominal wall muscles are broad and long muscles which lie on the anterior aspect of the abdomen. They are two in number: the rectus abdominis and the pyramidalis muscle. These paired muscles are situated on both sides of the linea alba, which is a fibrous median band extending vertically the entire length of the abdominal wall midline.
Action
The anterior abdominal wall muscles flex the trunk forwards as when we sit up and rise from a supine position or when we do sit-ups while working out. They are also part of the prelum abdominale. They maintain the intra-abdominal pressure at a certain level by their muscular tone, which is important for holding the abdominal organs in a definite position.
When the tonus of the anterior abdominal wall muscles reduces (atony), intra-abdominal pressure drops, as a result of which the organs are displaced downwards. On the other hand, contraction of these muscles reduces the capacity of the abdominal cavity and the organs are compressed backwards and upwards; this action helps in their evacuation (defecation, urination, and childbirth). As a result, they are called prelum abdominale.
Innervation
The anterior abdominal wall muscles are innervated by the intercostal and lumbar nerves ( T5 to T12 and L1).
Blood Supply
These muscles receives oxygenated blood from the superior and inferior epigastric artery, with the former originating from the internal thoracic and the latter from the external iliac artery.
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| Above, muscles of the anterior and lateral abdominal wall. The rectus abdominis muscle and the pyramidalis are located on the anterior abdominal wall. |