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SECTION I 



ANATOMY OF THE FOWL 



In the young bird the bones, for the most part, contain 

 cavities filled with red marrow. In the adult bird these cavi- 

 ties are largely filled with air. The air passes from the res- 

 piratory organs into these cavities. This air is supposed to 

 be renewed in the process of respiration. In the running 

 birds most of the bones contain marrow. Separate bronchial 

 tubes of the lungs are continued by the air sacs w^hich com- 

 municate with the air spaces of the bones. The air spaces are 

 more abundant in the larger bones as the humerus, ulna and 

 radius. 



The air passes into the air passages and bony cavities of 

 the head, then through the superior larynx, trachea and in- 

 ferior larynx into the bronchi. From air tubules here, the air 

 passes into the air cells of the body cavities and then into 

 the air cells of the bones. In the process of breathing the 

 air is drawn out of the air sacs located in the body and bone 

 cavities. Fresh air in turn is forced through the small com- 

 municating tubules which enter the hollow bones through 

 small openings in their bony Avails. 



For study of the skeleton it may be divided into the three 

 regions : head and neck, the trunk and the limbs. 



THE HEAD AND NECK 

 (The numbers refer to Fig. 1) 



The bird's head is rather small and conical in shape and 

 is composed of several bones as shown in Fig. 1. The os in- 

 cisivum or premaxilla (1) forms the anterior point and 

 base of the upper jaw. It is elongated anteriorly into a V 

 point in the fowl and flattened in the water fowl as the duck 

 and goose. This portion constitutes the beak. This bone, 

 together with the os dentale (6) forms the prehensile organ 

 or means of picking both solids and liquids. This organ con- 

 tains the anterior nasal opening (2) through which air passes 

 on its Avay to the lungs. The lamina perpendicularis of the 

 ethmoid l)one (5) forms a thin wall ])et\veen the two orbits 

 or eye cavities. It contains an opening or foramen for the 

 passage of the optic nerve and a smaller opening, the ethmoid 

 foramen, for the passage of the ethmoid nerve. The os 

 palatinum or palatine bone encircles the guttural opening of 

 the nasal passage and forms the greater part of the hard 



