Muscles at the front of the abdomen, showing the pyramidalis at the bottom centre.
|Origin||pubic symphysis and pubic crest|
|Artery||Inferior and superior epigastric arteries|
|Nerve||Subcostal nerve (T12)|
|Actions||tensing the linea alba|
|Anatomical terms of muscle|
Superiorly, the fleshy portion of the pyramidalis passes upward, diminishing in size as it ascends, and ends by a pointed extremity which is inserted into the linea alba, midway between the umbilicus and pubis.
The pyramidalis is innervated by the ventral portion of T12.
The pyramidalis muscle is present in 80% of human population. This muscle may be absent on one or both sides; the lower end of the rectus then becomes proportionately increased in size.
Occasionally it is double on one side, and the muscles of the two sides are sometimes of unequal size. It may also extend higher than the usual level.
The pyramidalis, when contracting, tenses the linea alba.