Page:Structure and functions of the body; a hand-book of anatomy and physiology for nurses and others desiring a practical knowledge of the subject (IA structurefunctio00fiskrich).pdf/196

 the pelvis and under Poupart's ligament, gradually diminishing in size, and terminates in a tendon that is inserted into the lesser trochanter. It serves to flex the thigh on the pelvis and to rotate it outward. The psoas parvus rises from the last dorsal and the first lumbar vertebræ and does not go out of the pelvis.

The sartorius or tailor muscle is flat and ribbon-like and is the longest muscle in the body. It rises from the anterior superior spine of the ilium and is inserted into the upper inner surface of the shaft of the tibia. By it the legs are crossed. It also forms the outer side of an important landmark, Scarpa's triangle, whose base is formed by Poupart's ligament and the inner side by the adductor magnus muscle, which passes from the ramus of the os pubis and the tuberosity of the ischium to the linea aspera. The femoral artery bisects the triangle and runs into its apex.

The bulk of the anterior portion of the thigh is formed by the quadriceps extensor, which is really made up of four muscles, the rectus femoris, whose origin is on the anterior inferior iliac spine and above the acetabulum; the vastus externus, which comes from the greater trochanter and the upper linea aspera; and the ''vastus internus and crureus'', which rise from the neck of the femur and the linea aspera. It is inserted into the tubercle of the tibia by the ligamentum patellæ, in which the patella lies. Its action is to extend the leg.

At the back and forming the buttocks are the three glutei muscles, the gluteus maximus, medius, and minimus. All these rise from the outer side of the ilium and have their insertion on or about the great trochanter. They serve to hold the trunk erect and to extend, abduct, and rotate the thigh.

Lower down and forming the back of the thigh are the biceps and the semitendinosus and semimembranosus muscles. The biceps rises by two heads from the tuberosity of the ischium and the linea aspera and is inserted into the head of the fibula. It is on the outer