MuscleAbdominal wall — anterolateral
Internal oblique
Latin: M. obliquus internus abdominis
Location: Abdomen
View the internal oblique in 3DOrigin
Iliac crest, thoracolumbar fascia and lateral half of the inguinal ligament.
Insertion
Inferior borders of ribs 10–12, linea alba and pubic crest; its cremaster fibres loop the spermatic cord.
Action
Rotates and side-bends the trunk ipsilaterally, compresses the abdomen and forms the conjoint tendon shielding the inguinal canal's posterior wall.
Nerve supply
T7–T12 and L1 (iliohypogastric, ilioinguinal).
Blood supply
Deep circumflex iliac and lower intercostal arteries.
Clinical relevance
Its aponeurosis splits around the rectus above the arcuate line; its cremasteric fibres mediate the cremasteric reflex (L1–L2) that lifts the testis when the inner thigh is stroked.
Educational anatomy reference, not medical advice. About this content.