Overview
The musculature of the thigh is divided into anterior, medial and posterior compartments, each with distinct innervation and function. The muscles in the posterior compartment of the thigh are collectively known as the hamstrings. The hamstring portion of the adductor magnus has a similar action to these muscles, but is located in the medial thigh.
Arterial Supply
The primary blood supply to the lower limb arises from the femoral artery and the inferior gluteal artery
Venous Drainage
The venous drainage in the lower limb is mainly through the great saphenous and small saphenous veins.
The veins located deep to the fascia help to drain the muscles while the veins that are superficial to the fascia help to drain the skin.
Lymphatic Drainage
Lymphatic drainage from the posterior thigh travels through various lymphatic vessels before reaching the deep inguinal nodes and, eventually, the external iliac nodes.
Biceps Femoris
Two-headed muscle, lateral most
- Attachments:
- The long head originates from the ischial tuberosity of the pelvis.
- The short head originates from the linea aspera on posterior surface of the femur.
- Both heads form a tendon, which inserts into the head of the fibula.
- Actions:
- Main action is flexion at the knee.
- It also extends the thigh at the hip and laterally rotates at the hip and knee.
- Innervation:
- Long head – Tibial part of the sciatic nerve (L4-S3)
- Short head – Common fibular part of the sciatic nerve (L4-S3)
Semitendinosus
The semitendinosus is a largely tendinous muscle which lies medial to the biceps femoris and covers the majority of the semimembranosus.
- Origin: Originates from the ischial tuberosity of the pelvis
- Insertion: Attaches to the medial surface of the tibia.
- Actions:
- Flexion of the leg at the knee joint.
- Extension of thigh at the hip.
- Medially rotates the thigh at the hip joint and the leg at the knee joint.
- Innervation: Tibial part of the sciatic nerve (L4-S3)
Semimembranosus
The semimembranosus muscle is flattened and broad. It is located underneath the semitendinosus.
- Origin: Originates from the ischial tuberosity, superior to the semitendinosus and biceps femoris
- Insertion: It attaches to the medial tibial condyle
- Actions:
- Flexion of the leg at the knee joint.
- Extension of thigh at the hip.
- Medially rotates the thigh at the hip joint and the leg at the knee joint.
- Innervation: Tibial part of the sciatic nerve (L4-S3)