DISEASES OF DOMESTICATED BIRDS 
CHAPTER I 
ANATOMY OF BIRDS 
The structure of birds differs in many respects from that of 
mammals and deserves a special description. The aim of the authors 
is to bring to the attention of the veterinarian the more important 
differences which are observed in the structure of domesticated birds 
as compared with that of domesticated mammals. The subject will 
be considered under the following sub-divisions. 1. Skeleton, 2. 
Musculature, 3. Circulatory system, 4. Nervous system, 5. Ali- 
mentary system, 6. Respiratory system, 7. Urinary system, 8. 
Generative system, and 9. The skin and its appendages. 
SKELETON 
Skull. The bones of the skull become united shortly after hatch- 
ing and lose their individual identity except in the case of the as- 
cending processes cf the premaxillary and nasal bones which are 
not rigidly joined to the frontal bone but through their cartilaginous 
attachment permit the elevation of the superior mandible. The in- 
ferior processes of the premaxillary bone, the supermaxillaries and 
the palatine bones which form the roof cf the palate do not meet 
in the median line, with the result that the palate presents an 
elongated opening or cleft. 
Vertebral column. The cervical vertebrae vary in number in 
the different species. Statements of anatomists differ concerning the 
number, because of difficulties experienced in defining cervical and 
thoracic vertebre. The atlas or first cervical vertebra is ring-like in 
form and articulates with the occipital bone of the skull by means of 
a deep coneavity into which the condyle of the occipital bone is re- 
ceived. This articular arrangement and that of the other cervical 
vertebrae gives the head and neck great mobility. The articular sur- 
face is concave from side to side and convex in a dorso-ventral direc- 
tion on the anterior extremity of each vertebra, presenting a saddle 
shaped appearance. The posterior extremity is the reverse, that is, 
concave dorso-ventrally and convex from side to side. 
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