_a_, M. tensor fasciæ latæ; _a′_, fascia lata; _b_, M. rectus femoris; _c_, M. vastus medialis; _d_, M. iliopsoas (cut); _e_, M. pectineus; _f_, M. adductor longus; _g_, M. adductor femoris; _h_, _h′_, M. semimembranosus; _i_, M. semitendinosus (_i′_, its tendon); _j_, medial head of M. gastrocnemius; _k_, M. popliteus; _l_, M. flexor longus digitorum. 1, patellar ligament; 2, ligamentum collaterale tibiale.] =M. pectineus= (Fig. 92, _e_).--A flat band of fibres closely united with the adductor longus (_f_), of which it appears to be a lateral continuation. _Origin_ by fleshy fibres from the lateral one-fourth of the cranial border of the pubis. The muscle passes over the smooth outer surface of the pubis between its origin area and the acetabulum, crosses the iliopsoas (_d_) obliquely and has its _Insertion_ by muscle-fibres into an elongated area (five millimeters in length) on the shaft of the femur just distad of the lesser trochanter and between the insertion of the adductor femoris (_g_) and that of the vastus medialis (_c_). _Relations._--The cranial edge forms part of the floor of the iliopectineal fossa. Lateral surface in relation with the iliopsoas (_d_) and vastus medialis (_c_); medial surface with the adductor longus (_f_) and adductor femoris (_g_). _Action._--Adductor of the thigh. =M. quadriceps femoris.=--The quadriceps femoris is a very powerful extensor muscle on the front of the thigh. It consists of four muscles which unite to form the great extensor of the shank. It is inserted into the patella and through it, by the ligamentum patellæ, into the tibia. It may be compared to the triceps brachii. The parts are: (1) =M. rectus femoris= (Fig. 92, _b_; Fig. 90, _c_). _Origin_ by strong tendon from an elongated triangular area which has its base at the acetabulum and its apex about five to seven millimeters craniad of the acetabulum, along the ventral border of the ilium. The area is between that for the capsularis and that for the iliopsoas. The muscle is flat near its origin, but soon becomes a triangular prismatic mass which is united to the dorsal border of the vastus lateralis (Fig. 90, _d_) at the junction of the middle and last thirds of the thigh. _Insertion_ into the oblique area on the outer surface of the patella near its proximal border in connection with the vastus lateralis. _Relations._--Outer or lateral surface at the origin with the gluteus minimus, the edge of the capsularis, the gluteus medius (Fig. 90, _b_), and farther distad with the vastus lateralis (Fig. 90, _d_). Medial surface with the tensor fasciæ latæ (Fig. 92, _a_), sartorius (Fig. 90, _a_), and vastus medialis (Fig. 92, _c_). Inner (caudal) surface with the vastus intermedius. (2) =M. vastus lateralis= (Fig. 90, _d_).--A flat triangular prismatic mass joined distally to the preceding. It covers the dorsal part of the lateral surface of the thigh.