Trunk (thorax, abdomen, back)

Pyramidalis

Musculus pyramidalis

Origin

Anterior surface of the pubis, just above the symphysis

Insertion

Linea alba, a few centimeters above the symphysis

Function

Tenses the linea alba

Innervation

Subcostal nerve (T12)

Movement & chain

Tenses the linea alba synchronously with rectus abdominis and transversus abdominis during abdominal bracing.

Palpation

Palpable immediately superior to the pubic crest on either side of the distal linea alba during abdominal tightening.

Clinical

Absent in about 20% of individuals; tenses the linea alba; key landmark for surgical midline identification in Pfannenstiel incisions (cesarean section).

Segmental innervation

Myotome T12.

In clinical practice

Wound management post-laparotomy/chest drain and abdominal wall monitoring; support incision site during coughing to prevent wound dehiscence.

Region in the model

Trunk (thorax, abdomen, back)