ANATOMY. AND i' PHYSIOLOGY OF • THE .HORSE. 



37 



they constitute four distinct bones, two on 

 each side. 



Q. Name them. — A. Two ossa tempo- 

 rum, pars squamosa, pars petrosa : four. 



Q. Describe their appearance. — One 

 pair is composed of laminas, vaulted ; form 

 ovoid, surmounted by irregular projections ; 

 the other pair are solid and convex. 



OCCIPITAL BONE (oS OCCIPITEs). 



Q. What is the situation of the os occi- 

 pites? — A. It is located in the postero- 

 superior and inferior parts of the cranium. 



Q. What is its form ? — A. Convex 

 externally, irregular, having an occipital 

 tuberosity and condyles. 



Q. What are the connections of this 

 bone ? — A. It unites, superiorly, with the 

 parietal bones ; inferiorly and anteriorly with 

 the sphenoid ; laterally, with the temporal, 

 and it articulates posteriorly with the atlas. 



Q. What is the foetal state of the bone ? 

 A. It is easily separable into four portions. 



Q. State its use. — A. It forms the pos- 

 terior and inferior parts of the cranium, 

 protects this portion of the brain, and gives 

 exit to the spinal cord. 



SPHENOID BONE (oS SPHENOIDES). 



Q. What is the situation of the os 

 sphenoides ? — A. It passes from one tem- 

 poral region to the other, across the antero- 

 inferior part of the brain. 



Q. What are its general divisions? — A. 

 It is divided into body, situated in the mid- 

 dle, alaB or wings, on each side, and two 

 pterygoid processes, considered as legs. 



Q. To what bones is it connected ? — A. 

 Occipital, ethmoid, squamous-temporal, pal- 

 ate, and vomer. 



ETHMOID BONE (oS ^THMOIDES). 



Q. What part of the cranium does the 

 OS aethmoides occupy ? — A. Anterior to 

 the sphenoid, and is the boundary of the 

 cranial, and commencement of the nasal, 

 cavities. 



Q. Describe its form. — ^. The posterior 

 portion bears resemblance to a bird with its 

 wings extended, having no legs, but a long 



erected neck and a smaU round head ; the 

 anterior part consists of a slim, brittle, 

 porous, spongy structure of considerable 

 volume. 



Q. What are its connections? — A. 

 With ,the sphenoid, frontal, vomer, and 

 superior turbenated bones; and with the 

 cartilaginous septum of the nose. 



BONES OP THE FACE. 



Under this head we shall consider the 



Ossa nasi, 



" maxillaria superiora, 



" maxillaria anteriora, 



" malarum, 



" lacrymalia, 



" palati, 



" tm-binati, superior et inferiora, 



" vomer, .... 

 Os maxillare inferus, (lower j aw,) 



Total, 18 



We shall now consider these bones in the 

 above order. 



NASAL BONES (oSSA NASi). 



Q. How many nasal bones are there ? — 

 A. Two. 



Q. Where are they situated? — A. In 

 the superior part of the face. 



Q. Describe their form? — A. They re- 

 semble the form of a pear ; are broad pos- 

 teriorly, pointed anteriorly ; they are convex 

 externally and concave internally. 



Q. To what bones are they connected ? 

 — -A. To the frontal, superior and anterior 

 maxillaria, and lachrymal. 



Q. What is theuruse?— A To defend 

 the nares, and retain in position the septura 

 nasi. 



SUPERIOR MAXILLARY BONES (oSSA MAXIL- 

 LARIA superiora). 



Q. Where are they situated? — A. In 

 the supero-lateral parts of the face. 



Q. Describe their form ? — A. They are 

 somewhat irregular — trilateral; from the 

 centre (which is thickest) they taper, the 

 anterior part being much thinner than the 

 posterior. 



Q. How are they divided? — A. Each 



