Hamstrings and Sciatic Nerve Relationship

Courtesy: Prof Nabil Ebraheim, University of Toledo, Ohio, USA

The Hamstring muscles arise from the Ischium and their function is to provide hip extension and knee flexion. There are 3 Hamstring muscles: 1) Biceps femoris (long and short head), 2) semi-tendinosus, 3) semi-membranosus.

Sciatic nerve is the largest nerve of the body which enters through the sciatic notch and passes underneath the piriformis muscle. Sciatic nerve is close to the Hamstring muscles (1.2cm lateral). It has medial (tibial) and lateral (peroneal) division. As sciatic nerve is lateral to the Hamstring muscles, it gives branches from its medial (tibial part) side.

In the upper part of the thigh, the Sciatic nerve is covered by the long head of Biceps femoris muscle. As the Sciatic nerve descends in the thigh close to the midline, it is crossed obliquely by the long head of biceps femoris muscle. This crossing of long head of Biceps femoris over Sciatic nerve look like ‘X’.

The short head of the Biceps femoris join with the long head of Biceps femoris in the distal thigh and it inserts into the fibular head. Innervation to the short head of Biceps femoris comes from the common peroneal nerve.

A high Sciatic nerve lesion can mimic a common peroneal nerve injury at the fibular head. Tightness in the Hamstring muscles can place increased stress on the lower back causing back pain and sciatica. Hamstring muscles injury is the most common injury in football players.