MUSCLES OF THE PELVIC LIMBS. 201 



the acetabulum, crosses the iliopsoas {d) obliquely and has its 



Insertion by muscle-fibres into an elongated area (five milli- 

 meters 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 mcdialis ((). 



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 {/) 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 patellae, into the tibia. It may be compared to the 

 triceps brachii. The parts are: 



(i) 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 ven- 

 tral 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, U), and farther distad with the vastus lateralis (Fig. 

 90, </). Medial surface with the tensor fasciae latae (Fig. 92, «), 

 sartorius (Fig. 90, a^, and vastus medialis (Fig. 92, r). Inner 

 (caudal) surface with the vastus intermedins. 



(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. 



Origin from a triangular area on the dorsal and lateral sur- 



