ANTERIOR FEMORAL REGIOX. 331 



synovial bursa. By its deep surface, with the Crureus, some large branches of 

 the external circumflex artery and anterior crural nerve being interposed. 



The Vastus interims and Crureus are so inseparably connected together, as to 

 form but one muscle. It is the smallest portion of the Quadriceps extensor. The 

 anterior portion of it, which is covered by the Rectus, being called the Crureus ; 

 the internal portion, which lies immediately beneath the fascia lata, is called the 

 Yastus Internus. It arises by an aponeurosis, which is attached to the lower part 

 of the line that extends from the inner side of the neck of the femur to the linea 

 aspera, from the whole length of the inner lip of the linea aspera, and internal 

 intermuscular septum. It also arises from nearly- the whole of the internal, 

 anterior, and external surfaces of the shaft of the femur, limited, above, by the line 

 between the two trochanters, and extending, below, to within the lower fourth of 

 the bone. From these different origins, the fibres converge to a broad aponeurosis, 

 which covers the anterior surface of the middle portion of the muscle (the Crureus), 

 and the deep surface of the inner division of the muscle (the Vastus internus) ; 

 becoming joined and gradually narrowing, it is inserted into the patella, blending 

 with the other portions of the Quadriceps extensor. 



Relations. By their superficial surface, with the Psoas and Iliacus, the Rectus, 

 Sartorius, Pectineus, Adductors, and fascia lata, femoral vessels, and saphenous 

 nerve. By its deep surface, with the femur, Subcrureus, and synovial membrane 

 of the knee-joint. 



The student will observe the striking analogy that exists between the Quadri- 

 ceps extensor, and the Triceps brachialis in the upper extremity. So close is this 

 similarity, that M. Cruveilhier has described it under the name of the Triceps 

 femoralis. Like the Triceps brachialis, it consists of three distinct divisions 

 .or heads; a middle or long head, analogous to the long head of the Triceps, 

 attached to the ilium, and of two other portions which have respectively received 

 the names of the external and internal heads of the muscle. These, it will 

 be noticed, are strictly analogous to the outer and inner heads of the Triceps 

 brachialis. 



The tendons of the different portions of the Quadriceps extensor unite at the 

 lower part of the thigh, so as to form a single strong tendon, which is inserted 

 into the upper part of the patella. More properly speaking, the patella may be 

 regarded as a sesamoid bone, developed in the tendon of the Quadriceps ; and the 

 ligamentum patellse, which is continued from the lower part of the patella to the 

 tuberosity of the tibia, as the proper tendon of insertion of this muscle. A syno- 

 vial bursa is interposed between the tendon and the upper part of the tuberosity 

 of the tibia. From the tendons corresponding to the Vasti, a fibrous prolongation 

 is derived, which is attached below to the upper extremities of the tibia and fibula. 

 It serves to protect the knee-joint, which is strengthened on its outer side by the 

 fascia lata. 



The Subcrureus is a small muscle, usually distinct from the superficial muscle, 

 which arises from the anterior surface of the lower part of the shaft of the femur, 

 and is inserted into the upper part of the synovial pouch that extends upwards 

 from the knee-joint behind the patella. This fasciculus is occasionally united with 

 the Crureus. It sometimes consists of two separate muscular bundles. 



Nerves. The Tensor vaginae femoris is supplied by the superior gluteal nerve ; 

 the other muscles of this region, by branches from the anterior crural. 



Actions. The Tensor vagina femoris is a tensor of the fascia lata ; continuing 

 its action, the oblique direction of its fibres enables it to rotate the thigh inwards. 

 In the erect posture, acting from below, it will serve to steady the pelvis upon the 

 head of the femur. The Sartorius flexes the leg upon the thigh, and, continuing 

 to act, the thigh upon the pelvis, at the same time drawing the limb inwards, so 

 as to cross one leg over the other. Taking its fixed point from the leg, it flexes 

 the pelvis upon the thigh, and, if one muscle acts, assists in rotating it. The 

 Quadriceps extensor extends the leg upon the thigh. Taking its fixed point from 

 the leg, as in standing, this muscle will act upon the femur, supporting it perpen- 



