The pyramidalis is a muscle that is considered insignificant in humans. Inferiorly, it attaches to the pubic symphysis and pubic crest. Superiorly, it attaches to the linea alba. Therefore, when contracting, it has the function of tensing the linea alba. It is absent in 20% of normal humans.

The Pyramidalis is a small triangular muscle, placed at the lower part of the abdomen, in front of the Rectus, and contained in the sheath of that muscle.

It arises by tendinous fibers from the front of the pubis and the anterior pubic ligament; the fleshy portion of the muscle 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.

This muscle may be wanting 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 extend higher than the level stated.

The muscle is innervated by the ventral portion of T12.

External links

Muscles of the trunk

%E9%8C%90%E4%BD%93%E7%AD%8B