ANTERIOR FEMORAL REGION. 409 



portion of the Quadriceps Extensor. The anterior portion of it, covered by 

 the Eectus, is called the Crureus ; the internal portion, which lies immediately 

 beneath the fascia lata, the Vastus 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 tne 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), a'nd which gradually narrows 

 down to its insertion into the patella, where it blends with the other portions of 

 the Quadriceps Extensor. 



Relations. By its 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 Quad- 

 riceps Extensor and the Triceps muscle 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 two other portions which may be called the external 

 and internal heads of the Triceps Femoralis. 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, the patella may be regarded 

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

 mentum patellas, which is continued from the lower part of the patella to the 

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

 synovial bursa is interposed between the tendon and the upper part of the tuber- 

 osity of the tibia. From the tendons corresponding to the Yasti, a fibrous pro- 

 longation is derived, which is attached below to the upper extremities of the 

 tibia and fibula, and which serves to protect the knee-joint, being strengthened 

 on its outer side by the fascia lata. 



The Subcrureus is a small muscle, usually distinct from the Crureus, but occa- 

 sionally blended with it, 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 syno- 

 vial pouch that extends upwards from the knee-joint behind the patella. 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 Vaginae Femoris is a tensor of the fascia lata ; continuing 

 its action, the oblique direction of its fibres enables it to rotate the thigh in- 

 wards. 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, flexes the thigh upon the pelvis, at the same time draw- 

 ing 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 the pelvis. The Quadriceps Extensor extend's the leg upon 

 the thigh. Taking its fixed point from the leg, as in standing, this muscle will 

 act upon the femur, supporting it perpendicularly upon the head of the tibia, 

 and thus maintaining the entire weight of the body. The Rectus muscle assists 

 the Psoas and Iliacus, in supporting the pelvis and trunk upon the femur, or in 

 bending it forwards. 



