THE SKELETON. 33 
posterior condyloid, opens more dorsally at the side of the 
condyle. The former transmits the twelfth (hypoglossal) 
cranial nerve, supplying the larynx, hyoid bone, and tongue. 
The jugular foramen, or foramen lacerum posterius, is at 
the juncture of the bulla, exoccipital, and basioccipital. 
The internal jugular vein and the ninth, tenth, and eleventh 
nerves pass through it. The basioccipital portion of this 
bone lies entirely on the ventral aspect of the skull. It 
articulates craniad with the basisphenoid by a suture which 
is generally obliterated in cats three or four years old. 
The sphenoid bone lies in the center of the base of the 
skull. It is composed of eight parts, corresponding to eight 
distinct bones in the lower vertebrates: the basisphenoid, 
articulating caudad with the basioccipital; two alisphenoids, 
extending dorsad from the basisphenoid and articulating 
caudad with the temporals (Figs. 17 and 18) two ptery- 
goids, projecting ventrally from the basisphenoid and 
terminating in sharp processes; a presphenoid in the mid- 
ventral line craniad of the basisphenoid; two orbitosphen- 
oids, extending dorso-laterally from the presphenoid and 
articulating craniad with the frontals. In an old cat, the 
sutures between these eight parts become more or less oblit- 
erated. The basisphenoid together with the alisphenoids 
is sometimes called the posterior sphenoid in distinction to 
the anterior sphenoid, composed of the presphenoid and 
orbitosphenoids. 
The basisphenoid presents on its dorsal or cerebral sur- 
face the sella turcica, or pitwitary fossa, which lodges the 
pituitary body of the brain (Fig. 90). The posterior 
boundary of this fossa is the clinoid plate, and its lateral 
ovale; p, presphenoid; p/, palatine; pt, pterygoid; pu, promontory 
of the petrous; po, postorbital process; pr, premolar teeth; pm, 
premaxillary; rd, fenestra rotundum; rt, foramen rotundum; st, 
stapes; sg, squamosal; sf, stylomastoid foramen; tc, carotid 
foramen, or foramen lacerum medius; vm, vomer, forming the 
septum between the posterior nares; 2g, zygomatic process of 
squamosal. 
