|Henry Gray (18251861). Anatomy of the Human Body. 1918.|
|contracted and thickened into a flat tendon inserted into the lateral border of the patella, blending with the Quadriceps femoris tendon, and giving an expansion to the capsule of the knee-joint.|
| The Vastus medialis and Vastus intermedius appear to be inseparably united, but when the Rectus femoris has been reflected a narrow interval will be observed extending upward from the medial border of the patella between the two muscles, and the separation may be continued as far as the lower part of the intertrochanteric line, where, however, the two muscles are frequently continuous.|
| The Vastus medialis (Vastus internus) arises from the lower half of the intertrochanteric line, the medial lip of the linea aspera, the upper part of the medial supracondylar line, the tendons of the Adductor longus and the Adductor magnus and the medial intermuscular septum. Its fibers are directed downward and forward, and are chiefly attached to an aponeurosis which lies on the deep surface of the muscle and is inserted into the medial border of the patella and the Quadriceps femoris tendon, an expansion being sent to the capsule of the knee-joint.|
| The Vastus intermedius (Crureus) arises from the front and lateral surfaces of the body of the femur in its upper two-thirds and from the lower part of the lateral intermuscular septum. Its fibers end in a superficial aponeurosis, which forms the deep part of the Quadriceps femoris tendon.|
| The tendons of the different portions of the Quadriceps unite at the lower part of the thigh, so as to form a single strong tendon, which is inserted into the base of the patella, some few fibers passing over it to blend with the ligamentum patellæ. More properly, the patella may be regarded as a sesamoid bone, developed in the tendon of the Quadriceps; and the ligamentum patellæ, which is continued from the apex of the patella to the tuberosity of the tibia, as the proper tendon of insertion of the muscle, the medial and lateral patellar retinacula (see p. 338) being expansions from its borders. A bursa, which usually communicates with the cavity of the knee-joint, is situated between the femur and the portion of the Quadriceps tendon above the patella; another is interposed between the tendon and the upper part of the front of the tibia; and a third, the prepatellar bursa, is placed over the patella itself.|
| The Articularis genu (Subcrureus) is a small muscle, usually distinct from the Vastus intermedius, but occasionally blended with it; it arises from the anterior surface of the lower part of the body of the femur, and is inserted into the upper part of the synovial membrane of the knee-joint. It sometimes consists of several separate muscular bundles.|
Nerves.The muscles of this region are supplied by the second, third, and fourth lumbar nerves, through the femoral nerve.
Actions.The Sartorius flexes the leg upon the thigh, and, continuing to act, flexes the thigh upon the pelvis; it next abducts and rotates the thigh outward. When the knee is bent, the Sartorius assists the Semitendinosus, Semimembranosus, and Popliteus in rotating the tibia inward. Taking its fixed point from the leg, it flexes the pelvis upon the thigh, and, if one muscle acts, assists in rotating the pelvis. The Quadriceps femoris extends the leg upon the thigh. The Rectus femoris assists the Psoas major and Iliacus in supporting the pelvis and trunk upon the femur. It also assists in flexing the thigh on the pelvis, or if the thigh be fixed it will flex the pelvis. The Vastus medialis draws the patella medialward as well as upward.
2. The Medial Femoral Muscles
| The Gracilis (Fig. 430) is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below. It arises by a thin aponeurosis from the anterior margins of the lower half of the symphysis pubis and the upper half of the pubic arch. The fibers run vertically downward, and end in a rounded tendon, which passes behind the medial condyle of the femur, curves around the medial condyle of the tibia, where it becomes flattened,