202 



SKELETON OF THE DOG 



BONES OF THE PELVIC LIMB 



The ilium is nearly parallel with the median plane and its axis is only sHghtly 

 oblique with regard to the horizontal plane. The gluteal surface is concave. The 

 pelvic surface is almost flat. The auricular surface faces almost directly inward, 

 and in front of it there is an extensive rough area. The ilio-pectineal line is very 

 distinct and is uninterrupted. The crest is strongly convex, thick, and rough. 

 The tuber sacrale is represented by a thickened part which bears two eminences, 

 homologous -^vith the posterior superior and posterior inferior iliac spines of man. 

 The tuber coxae also has two prominences, which are equivalent to the two anterior 

 spines present in man. The shaft is almost sagittal and is compressed laterally. 

 It is smooth and rounded dorsally, and it bears a ventro-lateral crest (Linea glu- 

 tae ventralis), which terminates at a tuberosity in front of the acetabulum. 



The ischium has a twisted appearance, owing to the fact that its acetabular 

 part is nearly sagittal while the posterior part is almost horizontal. The two bones 



Fig. 222. — Right Os Cox^ of Dog; Lateral View. 

 1, Gluteal surface of ilium; 2, crest of ilium; 3, tuber sacrale; 4, tuber coxae; 5, siiaft of ilium; 6, nutrient fora- 

 men; 7, greater sciatic notcli; 8, ventral gluteal line; 9, tubercle to which rectus femoris is attached; 10, ilio-pectiueal 

 eminence; 11, 11', acetabular and symphyseal branches of pubis; 12, articular surface of acetabulum; 12', fossa acetab- 

 uli; 13, obturator foramen; 14, ischiatic spine; 15, lesser sciatic notch ; 16, 16', acetabular and symphyseal branches 

 of ischium; 17, tuber ischii. 



also diverge behind and the tubera are flattened and everted. The superior ischiatic 

 spine is low and thick; its posterior part is marked by transverse grooves and has a 

 prominent outer lip. The greater sciatic notch is elongated and very shallow. There 

 is no lesser sciatic notch. The ischial arch is relatively small and is semi-elliptical. 



The symphyseal part of the pubis is thick and fuses late with the opposite bone. 

 There is no subpubic groove. 



The acetabulum is about twice as far from the tuber coxae as from the tuber 

 ischii. The fossa acetabuli is deep, and is bounded medially by a flat plate of bone; 

 its floor is so thin as to be translucent. There is a small notch behind. 



The obturator foramen resembles in outline an equilateral triangle with the 

 angles rounded off. 



Union of the three parts of the os coxae has usually taken place at six months, 

 but the epiphyses of the ilium and ischium do not fuse with the main part of these 

 bones till about the end of the second year. 



The inlet of the pelvis is very oblique. It is almost circular in the female, 

 but in the male it is elliptical and the conjugate diameter is the longer. The cavity 

 is narrowest between the acetabula, and very wide behind. The floor is concave 

 and relatively narrow in front, wide and flat behind. 



