ARTHROLOGY. Ill 



and pyriformis tendons ; the external surface of this liga- 

 ment gives attachment to some of the large muscles of the 

 quarter and over it, almost embedded in it, runs the great 

 sciatic nerve. Its inner surface affords attachment to re- 

 tractor ani and compressor coccygis. The obturator 

 ligament is an extremely thin layer of white fibrous tissue, 

 with difficnlty demonstrable, situated between the internal 

 and external obturator muscles, attached to the margins of 

 the foramen, deficient at the antero-external part, where 

 the obturator vessels and nerve gain passage. 



ARTICULATIONS OF THE HIND EXTREMITY. 



Hip -joint 



is formed by the head of the femur and the acetabulum, 

 maintained in apposition by ligaments. The acetabulum 

 is increased in depth by the circumfere^itial or cotyloid 

 ligament, a ring of fibro-cartilaginous substance attached 

 around its margin, it passes over the deficiency on the 

 inner side of the cavity, and here is termed the trans- 

 verse ligament; thus it leaves a space through which a 

 dense ligamentous band of a tendinous nature runs to 

 become attached to the break in the articular cartilage on 

 the head of the femur. This is the puhio -femoral ligament, 

 a continuation of the common tendon of the abdominal 

 muscles ; it runs from the anterior part of symphysis pubis 

 outwards through a groove on the under surface of os 

 pubis ; some of the muscular fibres of rectus abdominis 

 are directly inserted into it ; at its attachment to the 

 head of the femur it blends with ligamentum tenses, which 

 passes from here to the internal roughened part of the 

 acetabulum. From the free margin of the cotyloid liga- 

 ment the capsular ligament extends downwards, to become 

 attached around the outer margin of the articulatory 

 surface of the head of the femur ; it is lined by synovial 

 membrane, which also invests the pubio-femoral and teres 

 ligaments. 



Stifle joint 



corresponds to the knee of the human subject ; the pa- 

 tella, tibia, fibula, and femur assist to form it. Between 

 the condyles of the femur and the upper articulatory 

 surface of the tibia on either side is a semilunar disc of 

 fibro-cartilage. These are convex and thick externally 



