_F_, Pterygoid bone; _G_, horizontal and _G′_, perpendicular part of
palate bone; _H_, occipital bone; _J_, malar bone; _K_, sphenoid
bone; _O_, maxilla; _P_, vomer; _Sch._, squamous temporal; _St._,
frontal bone; _Z_, premaxilla; _1_, for. magnum; _2_, occipital
condyle; _3_, paramastoid (styloid) process of occipital; _4_,
hypoglossal and condyloid foramina; _5_, for. lacerum; _6_,
pharyngeal tubercles; _7_, bulla ossea; _8_, muscular process (left
one is removed to expose for. ovale); _9_, hyoid process; _10_, ext.
auditory meatus; _11_, zygomatic process; _12_, external opening of
parieto-temporal canal; _13_, postglenoid process; _14_, temporal
condyle; _15_, for. ovale; _16_, for. lac. orbitale + for. rotundum;
_17_, optic foramen; _18_, ethmoidal foramen; _19_, orbital opening
of supraorbital canal; _20_, pterygoid crest; _21_, hamulus of
pterygoid bone; _22_, lacrimal bulla; _23_, temporal process of
malar; _24_, pterygoid process of maxilla; _25_, sphenopalatine
foramen; _26_, maxillary foramen; _27_, posterior palatine foramen;
_28_, anterior palatine foramen; _29_, accessory palatine foramina;
_30_, palate process of maxilla; _31_, interalveolar border; _32_,
palatine cleft; _33_, palate process of premaxilla; _34_, fissura
incisiva; _35_, facial tuberosity; _36_, posterior nares.
(Ellenberger-Baum, Anat. d. Haustiere.)
]
The =parietal bones= do not enter into the formation of the roof of the
cranium. They constitute the upper part of the posterior wall, and bend
sharply forward along the lateral wall, forming part of the wall of the
temporal fossa. The line of inflection is marked by the prominent
=parietal crest=, which is continuous with the temporal crest below. The
parietals are excavated to form part of the frontal sinuses in the adult
animal.
The condition in the young subject is as follows: The two parietals
are united with each other and also with the interparietal and
supraoccipital. The resulting mass is somewhat horseshoe-shaped. Its
occipital part (Planum occipitale) forms the greater part of the
posterior wall of the cranium and bears about its center the
tuberosity for the attachment of the ligamentum nuchæ. From either
side of this a line curves outward, and divides the surface into an
upper smooth area and a lower area which is rough for muscular
attachment. The upper border joins the frontal bone and concurs in the
formation of the frontal eminence. The temporal parts (Plana
temporalia) are much smaller and are concave externally; they join the
frontal above and the squamous temporal below.
[Illustration: