OSTEOLOGY 35 



The Nasal Cavity. — The nasal cavity, or cavum nasi, is a lon- 

 gitudinal passage which extends through the upper part of the face. 

 It is divided into right and left halves by a median septum nasi. 

 Its walls are made up of the premaxiUa, maxilla, nasal, vomer, and 

 palatine bones. 



The Hyoid Bone. Location. — The hyoid bone, or os hyoideum, 

 is situated chiefly between the rami of the mandible, but its upper 

 part extends around the outer margin of the base of the skull. The 

 hyoid bone does not articulate with any bones of the skull, but is 

 firmly attached by strong fibrous structure. 



Description. — The hyoid bone consists of the following parts: 

 the body, or hasi-hyal, which is subcylindrical and presents in front 

 a trochlear articular surface, convex transversely, and concave 

 vertically for articulation with the ewer-shaped portion of the glosso- 

 hyal. The anterior free portion, or lingual process, is called the 

 glosso-hyal, or entoglossal bone. The lingual process gives support 

 to the muscular and fibrous structures of the tongue. On either 

 side of the basi-hyal there is a limb passing posteriorly along the 

 side of the superior larynx, extending upward along the outer border 

 of the occipital bone. This is the cornu of the os hyoideum and is 

 divided into two elements, first, the basi-hranchial which is bone and 

 articulates with the basi-hyal, and the second, the cerato-branchial , 

 cartilaginous in structure. In the center and projecting backward 

 from the body of the os hyoideum is a spur process called the uro- 

 hyal, partly bony and partly cartilaginous, and which rests upon 

 the superior larynx. 



THE VERTEBRAL COLUMN 



The vertebral, or spinal column consists of 42 bones, as shown in 

 the following table: 



Cervical region _ . . , 14 



Dorsal region 7 



Lumbo-sacral region 14 



Coccygeal region 7 



Total : . . . 42 



Many of the bones of the dorsal and lumbo-sacral regions do not 

 have free articulations. The cervical and coccygeal alone have free 

 movements. 



The Cervical Vertebrae (Fig. 4, No. 59; Fig. 5, Part II, No. 2). 

 Location. — The cervical vertebras form the neck of the fowl. 



