Gracilis muscle

The Gracilis (Latin: slender) is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below. It arises by a thin aponeurosis from the anterior margins of the lower half of the symphysis pubis and the upper half of the pubic arch.

The muscle's fibers run vertically downward, ending in a rounded tendon. This tendon passes behind the medial condyle of the femur, curves around the medial condyle of the tibia where it becomes flattened, and inserts into the upper part of the medial surface of the body of the tibia, below the condyle. At its insertion the tendon is situated immediately above that of the semitendinosus muscle, and its upper edge is overlapped by the tendon of the sartorius muscle, which it joins to form the pes anserinus. The pes anserinus is separated from the medial collateral ligament of the knee-joint by a bursa.

A few of the fibers of the lower part of the tendon are prolonged into the deep fascia of the leg.

Microsurgery
The gracillis muscle (also known as "the baby landing") is commonly used as a flap in microsurgery. According to the classification of Mathes and Nahai it presents a type II blood supply. This allows it to be transferred on its artery derived from the medial circumflex femoral artery. This artery enters the muscle about 10cm from the pubic symphysis. At this point (or 1cm proximal) the nerve also enters.

Transplantation Sites
The muscle may be split to reduce bulk for facial reanimation, as well as to repair hand muscles. It can be used to fashion an external anal sphincter.