thigh

thigh, region of the human lower limb located between the hip and the knee, containing the femur—the longest and strongest bone in the body—as well as major muscles, nerves, and blood vessels that support movement and weight-bearing. The thigh houses important neurovascular structures, including the femoral artery and vein and the sciatic nerve, making it a critical region for both locomotion and circulation.

The thigh is divided into anterior, medial, and posterior compartments, each with distinct muscle groups that perform specific functions. The anterior muscles, mainly the quadriceps, straighten the knee and help flex the hip. The posterior muscles, also known as the hamstrings, bend the knee and extend the hip. The medial muscles, or adductors, draw the thigh inward toward the midline of the body. Coordinated action of these groups provides both mobility and stability, making the thigh essential for weight-bearing and locomotion.

Injuries affecting the thigh commonly involve its muscles, bone, and neurovascular structures. Muscle strains, especially of the hamstrings and quadriceps, are frequent in athletes and often result from sudden acceleration or overuse. Contusions and intramuscular hematomas may occur after direct impact, sometimes leading to complications such as myositis ossificans (the formation of bone within muscle or other soft tissues). Fractures of the femur are serious injuries that can cause significant blood loss and require urgent management. Nerve compression or injury, including involvement of the femoral or sciatic nerves, can impair strength and sensation, whereas vascular injuries to the femoral artery pose life-threatening risks.