The muscles of the thigh in the anterior region
The Sartorius starts in the iliac of the spine and runs down and almost around the thigh bone and inserts in the surface of the tibial shaft and is responsible for flexing, abducting, and rotating the thigh. It also flexes and rotates the leg at the knee. The Iliacus starts at the area of the iliac spine and ends on a protuberance neat the top of the femur called the lesser trochanter together with the psoas major which begins at the twelfth thoracic vertebrae and ends at the same spot flexes thigh and if the thigh is still, it flexes the body so that it moves in a sitting up motion. The pectineus starts in the pubic area and inserts in the shaft of the top of the femur and moves the thigh itself. The rectus femorus starts in two places in the area of the iliac and ends at the knee cap and is responsible for extending the leg. The vastus lateralis, vastus medialis, and vastus intermedius all start in the shaft of the femur and end in a tendon that inserts into the knee cap and all are responsible for extension of the leg. The femoral nerve and branches of the lumbar plexus supply the nerve impulses to these muscles.
The muscles of the thigh in the medial region
There are four muscles in this area of the thigh. All of these muscles of the thigh from this area have their origin in the region of the pelvis known as the pubis. The gracilis inserts, or ends, in the shaft of the tibia. The other three, the adductor longus, adductor magnus, and adductor brevis all insert on the shaft of the femur these muscles mainly help to adduct, or move back inward from the side, the thigh. The three adductors are also involved in being able to rotate the thigh. This area is served by the obturator nerve and to a lesser extent a part of the sciatic nerve.
The muscles of the thigh in the posterior region
The muscles of the thigh that are in this region are all part of the hamstring group of muscles. The biceps femoris has two heads or origins one at the ischia area and one at the shaft of the femur these end at the top of the fibula bone ion the lower leg. Both are responsible for flexing the leg as well as for laterally rotating the leg. The semitendinosis and the semimembranosus start in the area of the ischia and end on the tibial staff. They act to flex and rotate the leg and to extend the thigh. The hamstring portion of the adductor magnus also is in this area and works to extend the thigh.
These muscles of the thigh do a great deal of work to move and stabilize the thigh and the whole of the body.