Lab 6 - Module 1 - The Gluteal Region: Page 6 of 8

Muscles of the Posterior Thigh

Add the Semimembranosus muscle.

Origin - Ischial Tuberosity

Insertion - Posterior aspect of the medial condyle of the tibia; gives off a reflected attachment that forms the oblique popliteal ligament. Semimembranosus is attached principally to the posterior surface of the medial tibial condyle. From this insertion several expansions from the tendon pass in different directions. One of the expansions (oblique popliteal ligament) runs supero-laterally behind the knee joint reinforcing the joint capsule. Another prominent expansion passes downwards and laterally to cover the popliteus muscle. This is called the ‘popliteus fascia’. A further expansion runs antero-medially along the medial aspect of the knee and partially blends with the capsule of the knee joint.

Innervation - Tibial Nerve

Action - Extend thigh, flex leg and internally rotate it when the knee is flexed

Add the Semitendinosus muscle.

Origin - Ischial tuberosity

Insertion - Medial surface of superior part of tibia

Innervation - Tibial Nerve

Action - Extend thigh, flex leg and internally rotate it when the knee is flexed

Rotate, focus and add the Pes anserinus which is a commonly used expression (though not one that is officially recognized in anatomical nomenclature) for the partly joined flattened tendons of the insertion of sartorius, gracilis and semitendinosus. These tendons are inserted onto the medial surface of the upper part of the tibia. The fancied resemblance of this arrangement to a goose's foot is the reason for the name! Within this arrangement, the tendons of gracilis and semitendinosus are relatively thick, strong and cord-like, whereas the sartorius tendon is almost fascial in its appearance.

The Biceps Femoris is a muscle of the posterior (hamstring) compartment of the thigh, and lies in the postero-lateral part of the thigh. Biceps femoris arises proximally by two ‘heads’ - termed the ‘long head’ and ‘short head’. The two heads of biceps femoris are innervated separately by the sciatic nerve; the long head of biceps femoris is supplied by the Tibial Nerve, and the short head by the Common Fibular Nerve.

Add the Short Head Biceps Femoris muscle. The Short Head is not a true hamstring muscle.

Origin - Linea aspera and lateral supracondylar line of the femur

Insertion - Lateral side of the head of the fibula; tendon is split at this site by the lateral collateral ligament (LCL)

Innervation - Common Fibular Nerve

Action - Flexes the leg and externally rotates it when the knee is flexed; extends the thigh

Add the Long Head Biceps Femoris muscle.

Origin - Ischial tuberosity

Insertion - Lateral side of the head of the fibula; tendon is split at this site by the lateral collateral ligament (LCL)

Innervation - Tibial Nerve

Action - Flexes the leg and externally rotates it when the knee is flexed; extends the thigh