Pyramidalis Muscle

The pyramidalis muscle is a pair of small, triangular muscles that are enclosed in the rectus sheath and are located anterior to the rectus abdominis muscle. They could work to tighten the linea alba, which is thought to not have any bearing on how the abdominal muscles work. Therefore, the muscles is considered one of the vestigial features of the human body. Moreover, the pyramidalis muscle's fleshy portion ascends superiorly, getting smaller as it goes, and terminates with a pointed endpoint that is inserted into the linea alba, which is situated midway between the umbilicus and pubis.

These muscles vary in size and in number, as some people could have more than one, and some people don't have pyramidalis muscle at all. According to several researches, pyramidalis muscles are present in about 80 percent of the human population. In some cases, the muscles may be absent on one or both sides, and the lower end of the rectus then would become proportionately increased in size, which means for those who have this muscles, their sizes are usually not even. In other cases, the muscles may also extend higher than the usual level.