Internal oblique
Musculus obliquus internus abdominis
MuscularDeep musclesAbdomenLeft and right
View left in 3D View right in 3D
- What it is
- Middle flat abdominal muscle, deep to the external oblique with fibres roughly at right angles to it: from the thoracolumbar fascia, anterior two-thirds of the iliac crest and lateral inguinal ligament up and forwards to the lower borders of ribs 10–12 and an aponeurosis that splits around rectus to reach the linea alba.
- Function
- Compresses the abdomen, flexes the trunk and rotates it to the same side (together with the opposite external oblique).
- Size
- About 20 cm tall, ~5 mm thick.
- Clinical note
- Its lowest fibres form the cremaster muscle around the spermatic cord and, with transversus, the conjoint tendon.