blood and nerve supply of the long head of biceps femoris muscle compared to the gracilis muscle

ABSTRACT

The material used in this study was 16 cadavers [5 fresh and 8 preserved adult cadavers and 3 stillborns]. The common iliac arteries of both sides in each cadaver were injected with lead oxide solution mixed with red latex in equal proportions. The gracilis and long head of biceps femoris muscles were exposed and dissected to identify their neurovascular bundles. The long head of biceps femoris got a major arterial pedicle from the inferior gluteal artery in all the cadavers dissected. It got also three major arterial pedicles in 75% of the cadavers and in 25% of the cadavers; it got only two major arterial pedicIes from the perforators of the profunda femoris artery. Each arterial pedicle was accompanied by two venae comitants that drained into the inferior gluteal or the profunda femoris veins. The long head of biceps muscle got also several minor arterial pedicles that entered the muscle at different and inconstant locations. The most distal major arterial pedicle lied at a mean distance of 25.3cm from the insertion of the muscle. The nerve supply to the long head of biceps femoris entered its middle third in 62.5% and the proximal third in 12.5% of the specimens. In 25% of the cases a single neural trunk originated from the sciatic nerve. It divided into two branches that entered the proximal and middle thirds of the muscle. The length of the long head of biceps femoris muscle ranged from 38 to 46cm with an average of 42cm. It was possible in all the dissected cadavers to rotate the long head of biceps femoris to wrap the anal canal. Regarding the gracilis muscle, the major arterial pedicles to it were at an average of 3 pedicles. Each pedicle entered the lateral surface of the muscle. In 87.5% of the dissected cadavers, the gracilis got 4 arterial pedicles from the medial circumflex femoral and the femoral arteries. In 12.5% of the studied cases there were two arterial pedicles that came from the medial circumflex femoral and the profunda femoris arteries. The arterial pedicles were accompanied by two venae comitants that drained into the profunda femoris or femoral veins. The nerve supply to gracilis muscle entered the middle third of the muscle with the proximal vascular pedicle or near it. The whole length of the gracilis muscle was averaging 41.7cm [38.4 to 42.3cm]. Consequent to the present study, both the long head of biceps and gracilis muscles are segmentally supplied and should be classified as type IV according the standard classification of Mathes and Nahai who classified them as type II. The nerve supplying the long head of biceps is easily detected and the muscle has a suitable length to wrap the anal canal. The long head of biceps femoris can be superior to the gracilis muscle in replacing a damaged anal sphincter as it can be transposed without sacrificing much of its major arterial pedicles