Authors: Emma Tubæk Nielsen, MD., Caroline Lilja, MD., and Magnus Balslev Avnstorp, MD.
Illustrator: Emma Tubæk Nielsen, MD.

The gracilis muscle is part of the thigh adductor muscle group, located posterio-medially to m. adductor longus. It aids in thigh adduction and hip flexion.

The muscle has tendinous origin from the inferior pubic ramus, pubic symphysis and ischium. It follows a straight course before inserting just below the tibial medial condyle, forming pes anserinus together with the sartorius fascia and semitendinosus tendon.

A perforating terminal branch from the medial circumflex femoral artery provides blood supply to the muscle, as it runs profound to the adductor muscles. It is a type II blood supply with one dominant vascular pedicle supplemented by multiple minor pedicles; these are usually ligated during flap harvest. Venous drainage is by the two venae comitantes which follow the course of the artery.

Motoric innervation arises from the anterior branch of the obturator nerve. Before entering the muscle, it divides into an inferior and a superior branche.^1,3,4

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