The pyramidalis is a small triangular muscle absent in 20% of individuals, lying in front of the lower rectus abdominis within the rectus sheath. It has no essential function and was more important in our quadrupedal ancestors.
| Origin | Anterior surface of the pubis and the pubic symphysis |
|---|---|
| Insertion | Linea alba — in the lower midline between the pubis and umbilicus |
| Nerve Supply | Subcostal nerve (T12) |
| Blood Supply | Inferior epigastric artery |
| Actions | Tenses the linea alba in the lower abdomen — the functional significance is debated |
|---|
The pyramidalis is the muscle used to locate the midline linea alba during lower abdominal surgery — it lies on either side of the midline and its medial borders define the linea alba exactly. In abdominoplasty and lower midline incision repair, identifying the pyramidalis guides midline fascial closure.
Not directly palpable — identified at surgery as the triangular muscle just above the pubis.
Pyramidalis muscle medial borders defining the linea alba precisely during lower abdominal surgery and fascial repair.
