THE SKELETON 



The number of bones in the skeleton of the cat varies with 

 its age, since two or more bones separate in the young may 

 form one mass in the old animal. The three portions of the in- 

 nominate bone which are distinct (Fig. 39) in the young, 

 become fused in the adult. In very old age many sutures of 

 the skull become partially or wholly obliterated. In the young 

 adult cat the number of bones, exclusive of the teeth, ear 

 bones, chevron bones, and sesamoid bones, is about 233. The 

 sacrum is reckoned as one bone, though composed of three 

 coalesced vertebrae. The structure and embryology of the 

 teeth show that they belong to a different category from the 

 bones. The ossicula auditus, or ear bones, are the malleus, 

 incus, and stapes of the middle ear. The chevron bones are 

 eight in number, attached to the ventral side of the vertebrae 

 of the tail. The sesamoid bones number about forty, of which 

 the patella, or knee-cap, is the largest. They are formed in the 

 tendons where there is much pressure or friction, as upon the 

 volar surface of the metacarpus. The outline on page 29 gives 

 the classification, names, and number of the different bones of 

 the skeleton. 



GENERAL TERMS USED IN DESCRIPTION OF BONES 



In reference to shape the bones are spoken of as long, short, 

 flat, and irregular. Long bones are those having a shaft or 

 diaphysis in which is a cavity filled with marrow, and two 

 enlarged extremities or epiphyses (Fig. 13) : femur, fibula, meta- 

 carpals, and phalanges. Short bones are those not elongated 

 and with no medullary cavity: tarsus and carpus. Flat bones 

 are plate-like, with a layer of cancellous tissue between two 

 layers of compact tissue: parietal, scapula, and innominate. 

 Irregular bones are those which have an exceedingly irregular 



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