THE FRONT OF THE THIGH 409 



The Quadriceps Femoris acts as a powerful extensor of the knee-joint. 

 It consists of four muscles, which are inserted into the proximal border of the 

 patella by a common tendon. They are all supplied by the femoral nerve 

 (L. 3 and 4). 



(i) The Rectus Femoris arises by a straight head; from the anterior inferior 

 iliac spine, and by a reflected head, which joins the former almost at right 

 angles, from the dorsum ilii just above the acetabulum. Near its origin 

 the muscle lies at the bottom of the depression between the tensor fasciae latae 

 and the sartorius (p. 398), and is in close relation to the anterior aspect of 

 the capsule of the hip-joint. After it has been crossed by the sartorius the 

 muscle becomes superficial, and it forms a well-marked elevation in the 

 middle line of the thigh when the knee is extended. 



(2) The Vastus Intermedius (Crureus) arises from the anterior and lateral 

 aspects of the shaft of the femur. It is partially overlapped by (3) the 

 Vastus Lateralis and (4) the Vastus Medialis. Both these muscles possess 

 linear origins from the linea aspera and the proximal part of the shaft of 

 the femur, but although the vastus medialis covers the medial aspect of the 

 bone, it gets no fibres of origin from it. 



At the sides of the patella the capsule of the knee- joint is greatly strengthened 

 by tendinous expansions, which it receives from the vastus lateralis and medialis. 



The Sartorius (p. 398) forms the lateral boundary of the femoral trigone 

 and the roof of the adductor canal, and then descends vertically on the medial 

 aspect of the thigh. It is inserted into the proximal part of the medial 

 surface of the tibia. The sartorius acts as a flexor and medial rotator of the 

 tibia, and as a flexor, abductor, and lateral rotator of the femur. It is 

 supplied by the femoral nerve (L. 3 and 4). 



Branches of the Femoral Artery. Near its commence- 

 ment the femoral artery gives off the superficial external pudenda! 

 (p. 253), the superficial epigastric (p. 253),, and the superficial 

 circumflex iliac. The last named runs laterally, parallel to the 

 inguinal ligament, and terminates in the anastomosis around the 

 anterior superior iliac spine (p. 416). 



The Deep External Pudendal Artery runs medially behind 

 the femoral vein and on the pectineus to supply the skin of the 

 scrotum. 



The Profunda Femoris usually arises about i| inches distal 

 to the inguinal ligament, and descends at first lateral and then 

 posterior to the femoral vessels. At the upper border of the 

 adductor longus the profunda leaves the femoral vessels by 

 passing behind the muscle. 



The profunda gives origin to several important branches. 



i . The Lateral Circumflex, which sometimes arises from the 

 femoral, springs from the profunda close to its origin. It passes 

 laterally, deep to the rectus and sartorius, where it is exposed 

 in the anterior route for excision of the hip (p. 434), and then 

 breaks up into : (a) an ascending branch, which joins the ana- 

 stomosis round the anterior superior spine of the ilium (p. 416) ; 

 (b) a transverse branch, which helps to form the crucial ana- 



