The skull forms a bony box which contains the brain and is produced craniad into the facial portion which encloses the nasal cavity and forms the framework of the face.

In dorsal view ([Fig. 39]) the skull presents a smooth convex surface, broadest caudad, with the two zygomatic arches (g) curving out some distance laterally. The following bones are visible in dorsal view: the occipital (1), interparietal (2), parietals (3), temporals (4), frontals (5), malar or zygomatic bones (6), nasals (7), maxillaries (8), premaxillaries (9), and lachrymals (10).

[Fig. 39].—Skull, Dorsal Surface.

1, occipital bone; 2, interparietal bone; 3, parietal bones; 4, temporal; 5, frontal; 6, malar; 7, nasal; 8, maxillary; 9, premaxillary; 10, lachrymal, a, lambdoidal ridge; b, external occipital tubercle; c, sagittal crest; d, parietal eminence; e, line which forms the dorsal boundary of the temporal fossa; f, zygomatic process of the frontal; g, zygomatic arch; h, frontal process of the malar; i, supraorbital arch; j, nares; k, foramen incisivum or anterior palatine foramen; l, sphenopalatine foramen; m, zygomatic process of the temporal; n, infraorbital foramen; o, opening of lachrymal duct.

The caudal boundary of the dorsal surface is marked by the prominent lambdoidal ridge (a) which passes from the middle cranioventrad along each side to the root of the zygomatic arch: it is borne by the occipital and temporal bones. From the middle of the lambdoidal ridge a second ridge, the sagittal crest (c), passes craniad in the middle line across the interparietal bone: it varies greatly in extent, reaching in a very old and muscular cat to the cranial border of the parietals, while in kittens it does not exist. The most prominent portions of the skull in this region, just craniad of the middle of the parietal bones, are known as the parietal tubercles or eminences (d). A faint curved line (e) runs from the cranial end of the sagittal crest craniolaterad to the base of the zygomatic process of the frontal: it marks the dorsal boundary of the origin of the temporal muscle, and may therefore be considered the dorsal boundary of the temporal fossa. This fossa extends from its dorsal boundary as far laterad and caudad as the lambdoidal ridge (a), and as far craniad as a line connecting the tip of the zygomatic process of the frontal (f) with the frontal process of the malar (h). The temporal muscle takes origin from its surface.

The middle portion of the dorsal surface is formed by the frontals (5). Each frontal presents laterally a prominent zygomatic process (f), extending ventrolaterad toward a corresponding (frontal) process (h) of the malar bone. These two processes mark the boundary between the orbital fossa (craniad) and the temporal fossa (caudad). Craniad of the zygomatic process of the frontal a sharp margin separates the dorsal surface of the skull from the wall of the orbital fossa: this is the supraorbital arch or margin (i).

The cranial portion of the dorsal surface is formed by the maxillary (8), nasal (7), and premaxillary bones (9). Just craniad of the nasals, bounded ventrad and craniad by the premaxillaries, appears the large opening of the nares (j), leading into the nasal cavity.

The zygomatic arch (g) is formed by the zygomatic process of the temporal (m) and the malar or zygomatic bone (6). Each presents near its middle a prominent dorsocaudally directed process, the frontal process (h) of the malar bone. The zygomatic arch forms the lateral boundary of the temporal and orbital fossæ, which are separated by a line connecting the frontal process of the malar (h) and the zygomatic process of the frontal (f).

A portion of the floor of the orbit and the opening of the lachrymal canal (o) may also be seen in dorsal view; they are described in connection with the [lateral surface].