10/02/2026
Very interesting case. A horse with a horizontal tear of the Biceps Femoris. As the bicep is torn all the way the compensation, secondary and instability this type of injury can cause is huge.
Biceps Femoris:
Lets take a look at one of the most powerful and complex muscles of the hindquarters, the biceps femoris. The Biceps Femoris is one of three hamstring muscles. Out of the three hamstrings, the biceps femoris is the largest & most lateral (farthest from the midline).
Biceps - A muscle with two points of attachment.
Femoris - Latin for femur. The long bone in the upper leg.
This means that the biceps femoris is a muscle with two points of attachment and is closely tied to the femur bone.
Funtion:
The biceps femoris has two origins. The first origin is along the sacral & caudal vertebrae, as well as the gluteal fascia and sacrotuberous ligament. The second origin is on the ischial tuberosity, which is the back part of the pelvis.
Moving down from the origins, the biceps femoris splits into three parts which are easily visible on many horses. These three parts include many insertion points including the patella (stifle), patella ligaments, tibia, achilles tendon and all of the surrounding crural fascia. One of the insertion points even goes down to the calcaneus, which is the bone at the back of the hock.
Because of the Biceps Femoris complexity, it has a wide array of functions. This is one of the few muscles that is able to both extend & flex a joint, in this case the stifle. It is also able to extend the hip and hock as well as abduct the limb (pull away from midline).
