thighs

The thighs are the regions between the hips and the knees. They contain the femur, muscles, nerves, vessels, and fat. The primary functions are to flex and extend the hip and knee, stabilize the pelvis, and transfer load during standing and locomotion.

Anatomy: The thighs are divided into three compartments by deep fascial partitions: anterior, medial, and posterior. The anterior compartment houses the quadriceps femoris (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius) and the sartorius and articularis genus. The medial compartment contains the hip adductors (adductor longus, adductor brevis, adductor magnus), gracilis, and pectineus. The posterior compartment contains the hamstring muscles (biceps femoris—long and short head, semitendinosus, semimembranosus).

Vessels and nerves: The femoral artery and its branches supply the anterior thighs; the deep femoral (profunda femoris) gives perforating arteries. The femoral vein accompanies the artery. Nerve supply follows compartments: the femoral nerve to the anterior compartments, the obturator nerve to the medial compartments, and the sciatic nerve to the posterior compartments. Lymph drainage mainly reaches the superficial inguinal nodes, with deep nodes along the femoral vessels.

Clinical notes: Thigh injuries are common in athletes. Quadriceps and hamstring strains, contusions, and muscle tears can occur with rapid acceleration, sprinting, or contact. Treatment emphasizes rest, rehabilitation, and gradual return to activity. Thigh pain can also reflect pathology in the hip or knee joints or in the vascular or nervous structures.

Additional notes: Variation exists in muscle size and tendon insertions. The thighs also include subcutaneous fat distribution that varies with body habitus and activity level.