The limbs become anatomically positioned at birth through the interaction of several growth factors. Limb buds develop from mesenchymal cells that are activated by lateral plate mesoderm around four weeks of gestational age. Muscles, bone, connective tissue, lymphatics, blood, and other structures originate from the mesoderm. The sciatic nerve and its two branches provide all motor innervation to the posterior thigh.Įach part of the human body develops from either ectoderm, mesoderm, or endoderm. As the sciatic nerve pierces the greater sciatic foramen, it travels down the posterior thigh posterior to the long head of the biceps femoris. The nerves of the posterior thigh originate from the lumbar and sacral plexuses. Within the posterior thigh, various neurovascular and lymphatic structures aid in moving fluid to and from the lower limb. The hamstring muscles in the open kinetic chain allow extension of the hip and flexion of the knee, and when in the closed kinetic chain, allow extension of the knee. These three muscles are collectively referred to as the hamstring muscles. The posterior thigh is composed of three muscles: biceps femoris long and short head, semitendinosus, and semimembranosus.

The femur is the bony structure that provides support to the muscles, nerves, and vasculature in the posterior thigh. Surgical: Open reduction and internal fixation (setting the fracture in the correct position and then fixing in place with metalwork).The posterior compartment of the thigh is separated from the anterior compartment by the lateral intermuscular septum and the medial compartment by the posterior intermuscular septum.Conservative: Rest, pain control and physiotherapy.Treatment of avulsion fractures of the ischial tuberosity can be conservative or surgical: It can be associated with sciatic nerve damage (the nerve lies in close location and could be compressed by a displaced fragment of bone). Patients with this injury often experience a sudden pain in the posterior thigh, followed by an inability to walk. In rare cases (predominantly adolescents), sudden and forceful contraction of the hamstrings can result in an avulsion fracture of the ischial tuberosity. The muscles of the posterior thigh all originate from the ischial tuberosity of the pelvis. Clinical Relevance: Hamstring Avulsion Fracture of the Ischial TuberosityĪn avulsion fracture occurs when a fragment of bone attached to a ligament or tendon gets pulled away from the main mass of the bone. In this article, we shall examine the anatomy of the muscles in the posterior thigh - their attachments, actions and clinical correlations. They are innervated by the sciatic nerve (L4-S3). The muscles in the posterior compartment of the thigh are collectively known as the hamstrings. They consist of the biceps femoris, semitendinosus and semimembranosus, which form prominent tendons medially and laterally at the back of the knee.Īs group, these muscles act to extend at the hip, and flex at the knee. Attachments: Originates from the ischial tuberosity (more superiorly than the origin of the semitendinosus and biceps femoris).It is located deep to the semitendinosus on the medial aspect of the posterior thigh. The semimembranosus muscle is flattened and broad. Innervation: Tibial part of the sciatic nerve.Medially rotates the thigh at the hip joint and the leg at the knee joint. Actions: Flexion of the leg at the knee joint.Attachments: Originates from the ischial tuberosity of the pelvis and attaches to the medial surface of the tibia.It is situated on the medial aspect of the posterior thigh and superficial to the semimembranosus. The semitendinosus is a largely tendinous muscle. Innervation: Long head innervated by the tibial part of the sciatic nerve, whereas the short head is innervated by the common fibular part of the sciatic nerve.

It also extends the thigh at the hip, and laterally rotates at the hip and knee.

Actions: Main action is flexion at the knee.

Together, the heads form a tendon, which inserts into the head of the fibula. The short head originates from the linea aspera on posterior surface of the femur.

Attachments: The long head originates from the ischial tuberosity of the pelvis.

The common tendon of the two heads can be felt laterally within the popliteal fossa (posterior knee region). The biceps femoris has two heads (long head and short head) and is the most lateral of the muscles in the posterior thigh. Note: The hamstring portion of the adductor magnus has a similar action to these muscles, but is located in the medial thigh. The muscles located within the posterior compartment of the thigh are the biceps femoris, semitendinosus and semimembranosus.

Posterior thigh compartment syndrome