The rectus abdominis is a muscle of the anterior abdominal wall. It is a paired, large, and flat muscle which lies on both sides of the linea alba (white line), which is a fibrous band that runs vertically the whole length of the anterior abdominal wall midline, from the xiphoid process to the pubic symphysis.
The rectus abdominis muscle arises from the fifth, sixth, and seventh costal cartilages, and the xiphoid process (lower portion of sternum). As it runs downwards, it becomes narrower. It is inserted into the pubic bone in the space between the pubic symphysis and tubercle. The muscle fibers of the rectus abdominis are interrupted by three or four transverse tendinous intersections, two of which are above the umbilicus, one is on the level with it.
Action/function
This flat muscle of the anterior abdominal wall flexes the trunk forwards, also tensing the linea alba.
Innervation
The rectus abdominis is innervated by the intercostal and lumbar nerves (from T5 to T12 and L1).
Blood Supply
This abdominal wall muscle is supplied by two blood vessels: the 1) superior epigastric artery, which arises from the internal thoracic, and the 2) inferior epigastric artery, which originates from the external iliac artery.
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| Above, the rectus abdominis, pyramidalis, and transversus abdominis muscle. |
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