ANATOMY OF THE HORSE. 39 



occipital notch ; in front of the notch and root of the occipital sty- 

 loid projection, THE PETROUS PORTION of the temporal bone — 

 exhibiting, posteriorly, the posterior mastoid process^ having at 

 its root the external orifice of the aqueduct of the vestibule: di- 

 rectly in front, the auditory process and meatus, at the inner side- 

 of which ig the hyoideal process ; behind the meatus are the 

 mastoid cells; projecting from the inner and anterior part, is the 

 slender temporal styloid process, having at its root the Eustachian 

 opening and styloid foramen. In front of, and rather outwardly 

 to the petrous portion, we observe, — the anterior mastoid process ; 

 at its root, the mastoid foramen ; extending outwardly, in front of 

 it, the glenoid cavity, bounded anteriorly by the temporal articu- 

 lar process. The foramen lacerum is the large irregular opening 

 formed by the occipital, temporal, and sphenoid bones, compre- 

 hending the tempero-occipital and spheno- occipital hiatus, and 

 traversed by the internal carotid artery, the jugular vein, the 

 eighth pair of nerves, and the inferior maxillary nerve. This fora- 

 men is bounded in front by the ala of the sphenoid bone, whose 

 borders are joined to the temporal and ethmoid bones by the sphe- 

 noidal suture. Curving forwards and downwards from the ala is 

 the pterygoid process : it articulates along its front part with the 

 palatine styloid process, which is comparatively slender and de- 

 scends beyond it. At the root of the pterygoid process is seen the 

 pterygoid for amen, forming one continued passage with the infero- 

 posterior orbital hole. 



2. The inferior facial region constitutes the remain- 

 der of the inferior surface : it is bounded, posteriorly, by the 

 sphenoid and ethmoid bones; and, anteriorly, by the incisive teeth. 

 Beginning from behind, we perceive, — in the middle, the broad 

 part of the vomer, embracing the body of the ethmoid ; and its 

 superior cornua extending under that of the sphenoid bone, at 

 whose points are found the spheno-palatine foramina, which open 

 again under the infero-posterior orbital : anteriorly to this it arti- 

 culates with the palate bones, both laterally and along their mid- 

 dle — Laterally, the palatine styloid processes, and the nasal and 

 palatine surfaces and borders of the palate bones, by which latter 

 is formed the posterior opening of the nose : this aperture in its 

 general figure is oval lengthwise, and is equally divided into two 

 semilunar halves by the shaftofthe vomer, aboutone-third of whose 

 length is seen through the orifice. Farther outward, on the sides 

 of this opening, the maxillary tuberosities ; immediately above 

 them, the maxillary hiatus or entrance io the posterior palatine 

 foramen, the infra-orbital canal, and the anterior palatine cofi- 

 duit : extending forward from the tuberosities in parallel lines, 

 the alveolar processes and cavities for the twelve superior molar 



