168 



ANATOMICAL TEGBNOLOGT. 



§ 451. Fossa cotyloidea — Cotyloid fossa, Acetabulum. — The 

 cotyloid fossa is a deep cup-shaped cavity in the lateral aspect of 

 the innominate bone which articulates diarthrodially with the head 

 of the femur. The third of the circumference of the cavity next the 



obturator foramen is absent, thus 

 producing the cotyloid notch. A 

 rough depression extends from 

 this notch about half way across 

 the floor of the fossa. 



§ 452. Ilium.— This is the ce- 

 phalic part of the os innomina- 

 tum. It articulates with the 

 sacrum and forms a considerable 

 part of the cotyloid fossa. 



§ 453. Ischium — The dorso- 

 caudal part of the pelvic bone. 

 It forms a large part of the coty- 

 loid fossa and about one third of 

 the pubic symphysis. 



§ 454. Os cotyloideum — Co- 

 tyloid bone. — A small bone form- 

 ing the ventral part of the floor 

 of the cotyloid fossa. Straus- 

 Durckheim, A, I, 502; Milne- 

 Edwards, A, X, 358. It has not 

 been detected in man, and can be 

 seen as a separate bone only in 

 immature cats. 



§ 455. Os iunominatum — In- 

 nominate or pelvic bone. — The os 

 innominatum is made up of the 

 ilium, the ischium, the os pubis 

 and the os cotyloideum. These 

 four bones are completely united 

 in adult life. The right and left pelvic bones together form the 

 pelvic girdle. 



§ 456. Os pubis — Pubic bone. — It is the cephalo-ventral of the 

 bones forming the pelvic girdle. It forms only a small part of the 

 cotyloid fossa and about two thirds of the symphysis pubis. 



% 457. Pelvis, az. — "The two innominate bones, together with 



Fig. 51. — Ventral View of the Cat's 

 Pelvis WITH Adjacent Veetebh^. 

 (Modified from Straus-Durckbeim.) 

 xl. 



