128 Anatomy of the Rabbit. 



structure, articulated with the main body of the skull by a typical 

 joint. 



The skull is roughly divisible into two portions, namely, an 

 anterior, facial portion, and a posterior, cranial portion The 

 cranial portion has a somewhat conical shape, its apex being directed 

 forward. It is separated from the facial portion by a depression 

 on either side of the skull, the orbital cavity (orbita), which serves 

 for the accommodation of the optic bulb. Unlike the remaining 

 special sense-organs, the eye is not included within the skull-wall. 

 The two portions are united both medially and laterally, the lateral 

 connection being established by the zygomatic arch (arcus 

 zygomaticus) , which bridges the lateral portion of the orbit. The 

 facial portion has also a somewhat conical shape, its apex being 

 formed by the anterior extremity of the upper jaw and the incisor 

 teeth. Its base is formed in part by the connection with the cranial 

 portion, as already described, and also by the anterior walls of- the 

 orbits. 



The cranial portion exhibits an extensive posterior, nuchal 

 surface (planum nuchale), situated in general at right angles to the 

 cervical portion of the vertebral column and also to the dorsal, 

 lateral, and ventral walls of the skull. This surface includes the 

 external surface of the occipital bone, with the exception, chiefly, 

 of the basilar portion of the latter. Its dorsal portion forms an 

 area of attachment for the spinal and special occipital musculature. 

 Its ventral portion is perforated by a large aperture, the foramen 

 magnum occipitale, for the passage of the central nervous system 

 from the cranial cavity into che vertebral canal. On either side 

 of this is a smooth, ridge-like projection, the occipital condyle 

 (condylus occipitalis), for articulation with the superior articular 

 pits of the atlas. At a little distance lateral to the occipital condyle, 

 the nuchal surface is continued downward through the medium of a 

 somewhat triangular, pointed jugular or paramastoid process 

 (processus jugularis). This structure is separated from the occi- 

 pital condyle by a pronounced notch, the posterior boundary of a 

 deep narrow excava,tion, the jugular fossa (fossa jugularis), which 

 lies between the condyle and the tympanic bulla. The jugular 

 process serves for the attachment of muscles belonging to the 

 tongue, hyoid, and mandible, namely, the styloglossus, stylohyoidei 



