488 A MANUAL OF ANATOMY 



external iliac. This last valve is known as the ilio-femoral valve 

 of Bennett. 



Varieties of the Femoral Vein. — i. The vein is sometimes absent from 

 Hunter's canal. In such cases, instead of passing through the femoral 

 opening in cpnnection with the adductor magnus, it ascends for some distance 

 upon the posterior surface of that muscle, which it subsequently pierces, and 

 so enters Scarpa's triangle. 



2. The vein may be double, simulating the arrangement known as venae 

 comites, in which case the femoral artery would have a vein on either side 

 of it, with communicating branches passing between the two at frequent 

 intervals over the vessel. 



Obturator Artery .^r-This vessel normally arises from the anterior 

 division of the internal iliac, and for the most part is placed 

 on the outer wall of the pelvic cavity. The artery, having 

 passed through the obturator canal, divides at once into its two 

 terminal branches, internal and external. These descend upon the 

 anterior surface of the obturator membrane under cover of the 

 obturator externus, the internal branch coursing along the inner 

 margin, and the external along the outer margin, of the membrane. 

 The internal branch supplies the obturator externus and adjacent 

 adductor muscles. The external branch divides into two at the lower 

 part of the obturator membrane. One of these divisions passes 

 inwards and anastomoses with the internal branch, thus completing 

 an arterial loop at the circumference of the membrane. The other 

 division takes an outward course below the acetabulum to the 

 region of the tuber ischii, where it supplies the origins of the ham- 

 string muscles and anastomoses with the sciatic artery. This latter 

 division supplies an articular branch to the hip- joint, which passes 

 beneath the transverse ligament. The external branch, in addi- 

 tion to the foregoing offsets, supplies the obturator externus, in 

 which both terminal branches anastomose with the internal 

 circumflex of the arteria profunda femoris. 



The obturator vein terminates in the internal iliac vein. 



THE HIP-JOINT. 



The hip-joint belongs to the class diarthrosis, and to the sub- 

 division enarthrosis. The articular surfaces are the head of the 

 femur and the acetabulum of the os innominatum. The ligaments 

 are the capsular ligament, with its accessory parts, the ligamentum 

 teres, the cotyloid ligament, and the transverse ligament. 



The capsular ligament is of great strength, and completeh' 

 surrounds the joint. It is tight-fitting, and hardly admits ol 

 separation taking place between the articular surfaces. Its 

 superior attacliments are as follows : above and behind it is 

 attached to the os innominatum immediately external to the coty- 

 loid ligament and about three lines from the brim of the acetabulum. 

 In front it is attached to the base of the anterior inferior ihac 



