Trunk (thorax, abdomen, back)

External Oblique

Musculus obliquus externus abdominis

Origin

Outer surface of the 5th through 12th ribs

Insertion

Iliac crest, pubic tubercle and, via the aponeurosis, the linea alba

Function

Flexion and rotation of the trunk (to the opposite side), compression of the abdominal contents

Innervation

Thoracoabdominal nerves (T7-T11), subcostal nerve (T12), iliohypogastric/ilioinguinal nerve (L1)

Movement & chain

Works unilaterally together with the contralateral internal oblique in trunk rotation movements; bilaterally in flexion and in abdominal straining together with rectus abdominis.

Palpation

The fibers are easily felt running obliquely caudomedially on the lateral abdominal wall, especially during a 'crunch with rotation'.

Clinical

Overuse during rotational sports movements (rowing, golf) can lead to muscle pain or, rarely, a sports hernia in the groin region.

Segmental innervation

Thoracoabdominal nerves and subcostal nerve, myotomes T7-T12; iliohypogastric/ilioinguinal nerve, L1.

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)