48 ANATOMY OF THE DOMESTIC FOWL 



THE PELVIC GIRDLE (Fig. 4, No. 25; Fig. s, Part II, 6) 



The pelvic girdle is made up of three bones as follows: the ilium, 

 the ischium, arid the pubis, all of which are fused in adult life. 

 They are separate in the baby chick (Fig. 5, Part II, 6). The pelvis 

 together with the lumbo-sacral vertebrae forms a thin, irregular, 

 shell-like structure extending superiorly from the tail to the thoracic 

 region. The sacrum is broad posteriorly and together with the 

 ilium forms the pelvic roof. The ilium and ischium are its lateral 

 walls. 



The top surface of the pelvis shows the fovea ilio-lumbalis dorsalis, 

 which is bounded mesially by the crista ilii. Between it and the 

 spina lumbalis there is a broad furrow, the bottom of which is formed 

 by the dorsal surface of the lumbar vertebras. The sulcus ilio- 

 lumbalis dorsalis is formed by the rims of the ilia, so that a ridge is 

 observable. The cavum ilio-lumbale dorsale is formed by the iliac 

 rims on either side. Anceriorly is the canalis ilio-lumbalis, which is 

 formed by the ilium and the lumbar vertebral spines. It is located 

 longitudinally to the vertebrae. • The anterior opening of this canal 

 is the larger. Posterior to the acetabulum is the post-acetabular 

 ridge. 



The under part of the pelvis presents three distinct regions. 

 The cavity is divided into the fovea lumbalis, or anterior part, 

 the fovea ischiadica, or mesial part, and the fovea pudendalis, or 

 posterior part. Posterior to these is the region called the planum 

 coccygeum. 



The fovea lumbalis contains the anterior lobe of the kidney, 

 and is circumscribed anteriorly by the last rib-carrying vertebra, 

 and posteriorly by the transverse process of the last lumbar 

 vertebra. 



In the fovea ischiadica which follows, lie the nerve plexus 

 ischiadicus and the middle lobe of the kidney. Its posterior 

 boundary is the linea arcuata. The linea arcuata is a line drawn 

 from the acetabulum of the one side to the acetabulum of the other 

 side. 



The fovea pudendalis contains the posterior lobe of the kidney. 



The posterior bovmdary is the anterior border of the first coccygeal 



vertebra. It gives passage to the nerve plexus pudendo-hemor- 



rhoidalis. 



The iUiun, the ischium, and the pubis join to form the cotyloid 



