Trunk (thorax, abdomen, back)

Rectus Abdominis

Musculus rectus abdominis

Origin

Pubic crest and pubic symphysis

Insertion

Costal cartilage of ribs 5-7 and the xiphoid process

Function

Flexion of the trunk (spine); compresses the abdominal contents, raises intra-abdominal pressure during straining, coughing, and bearing down during defecation/childbirth

Innervation

Thoracoabdominal nerves (T7-T12)

Movement & chain

Works together with the oblique abdominal muscles in trunk flexion and rotation; interrupted by three to four tendinous intersections that divide the muscle into separate bellies ("six-pack")

Palpation

Clearly visible and palpable as vertical muscle bellies on either side of the linea alba, especially during a crunch movement

Clinical

Diastasis recti (widening of the linea alba) is a common consequence of pregnancy; excessive training can contribute to an anterior pelvic tilt if not balanced with the back extensors

Segmental innervation

T7-T12

In clinical practice

Relevant as an anatomical landmark during ultrasound and surgical incisions of the abdominal wall (e.g. paramedian incision); diastasis recti is assessed in practice with a finger-width test at the level of the navel.

Region in the model

Trunk (thorax, abdomen, back)