Anatomy overhaul: the biceps femoris

The biceps femoris muscle is the most lateral component of the so-called hamstring muscles.  Classically, its origin and insertion have been sited as starting at the ischial tuberosity (composing the lateral most portion of the common hamstring insertion) and ending in the lateral knee at the head of the fibula.  However anatomical studies have shown both its origin and insertion to consist of far more complex and elaborate attachments which in tern has led to the discovery that this muscles function is far more important than simply flexing the knee.

Tubbs et al. 2006 in the journal Clinical Anatomy describe the results of examination of 56 dissected cadaver specimens paying close attention to the insertion of the biceps femoris.  The tendon was found to have both medial and lateral slips each with an anterior and posterior component.  In addition to the attachment points on the fibula, attachments were noted on the lateral femoral condyle of the femur; the popliteus tendon; the arcuate popliteal ligament; and into the crual fascia of the leg.  They hypothesize that due to the complex lateral leg attachments, that this muscle may be far more important to lateral knee stability than had previously been thought.

Proximally, the work of Vleeming brought to light the strong fascial connection between the proximal hamstring tendon (especially the contribution of the biceps femoris) and the Sacrotuberous ligament…which continues superiorly with the dorsal sacral ligament…which continues superiorly with the thoracolumbar fascia and lumbar erectors.  This proximal fascial sling is of utmost importance with in the treatment of conditions such as Sacroiliac joint pain, proximal hamstring tendonopathy, and low back pain.

In the book ‘Anatomy Trains,’ Myers describes the concept that the body is made up of a single muscle separated into hundreds of fascial compartments.  This is apparently the case for this very clinically important muscle which just so happens to be the most commonly injury muscle in the hamstring group.

For clinical information including discussion on diagnosis and treatment for the hamstring group, I highly recommend the two part series by Hoskins and Pollard published in ‘Manual Therapy’:

The management of hamstring injury – Part 1: Issues in Diagnosis. Manual Therapy, Volume 10, Issue 2, Pages 96-107, May 2005, Authors:Wayne Hoskins; Henry Pollard.

The management of hamstring injury – Part 2: Treatment. Manual Therapy, Volume 10, Issue 3, Pages 180-190, August 2005, Authors:Wayne Hoskins; Henry Pollard.