The skull of the ox is more clearly pyramidal than that of the horse,
and is shorter and relatively wider. The cranium is quadrangular and
larger externally than in the horse; its large size is due mainly to the
great extent of the frontal sinus, and does not affect the cranial
cavity, which is smaller than in the horse.
The =superior= or =frontal surface= is formed by the frontals, nasals,
and premaxillæ. The frontal part is quadrilateral and very extensive,
the greatest width being at the orbits. It presents a central depression
on its anterior part, and on either side are the supraorbital grooves
and foramina. Behind is the median frontal eminence, and at the lateral
angles the “horn-cores” project in horned cattle. The nasal part is very
short. The osseous nasal aperture is wide. The premaxillæ do not bend
downward as in the horse; they are relatively thin and weak, and are
separated by an interval which has a wide anterior part in place of the
foramen incisivum.
The =lateral surface= is more triangular than in the horse. The temporal
fossa is confined to this surface. It is deep and narrow, and its
boundaries are more complete. It is limited above by a crest which
extends from the postero-external angle of the frontal to the
supraorbital process, and is analogous to the sagittal crest of the
horse. Behind it is bounded by the temporal crest. It is clearly marked
off from the orbit by the rounded posterior orbital ridge and the
pterygoid crest. The zygomatic process is short, weak, and flattened,
and is formed by the temporal and malar only. Its condyle is convex and
is wide from before backward. The glenoid cavity and postglenoid process
are small. The orbit is encroached upon below by the lacrimal bulla, and
presents the orifice of the supraorbital canal behind. The margin is
completed behind by the frontal process of the malar; its lower part is
prominent and rough, not smooth and rounded as in the horse. The
pterygo-palatine fossa is much larger, deeper, and more clearly defined.
It has a long narrow forward extension (maxillary hiatus) between the
vertical plate of the palate bone internally and the maxilla and
lacrimal bulla externally; thus the sphenopalatine and maxillary
foramina are deeply placed. The preorbital region is short but
relatively high. A tuberosity and curved line take the place of the
facial crest. The infraorbital foramen is situated above the first cheek
tooth and is often double.
The =basal surface= is short and wide, especially in its cranial part.
The occipital condyles are limited in front by transverse ridges. The
tubercles at the junction of the occipital and sphenoid are large. The
condyloid fossæ contain two foramina, the hypoglossal below and in
front, and the condyloid above and behind; other inconstant ones occur.
The paramastoid processes are short and convergent. The foramen lacerum
is slit-like. The bulla ossea is a large, laterally compressed
prominence. The muscular processes are usually long and narrow
triangular plates, with one or two sharp points. The external auditory
process is directed almost straight outward. A curved plate extends
downward from it and joins the bulla ossea internally, completing the
deep cavity which receives the articular angle of the hyoid bone. The
chief external opening of the temporal canal is in front of this plate,
and an accessory one lies behind it. The infratemporal fossa is small,
and presents the foramen ovale. The posterior nares are very narrow, and
the vomer does not reach to the level of their margin. The hard palate
is wide, and forms about three-fifths of the entire length of the skull.
A small central part only of its posterior border enters into the
formation of the posterior nares; the lateral parts are notched and just
above them are the posterior palatine foramina. The anterior palatine
foramina are an inch or more from the posterior margin, and about the
same distance apart. The palatine grooves are distinct for a short
distance only. Just beyond the cheek teeth the palate narrows and
becomes concave; beyond this it widens and flattens.
The =posterior= or =nuchal surface= is extensive and somewhat pentagonal
in outline in the adult. About its center is the eminence for the
attachment of the ligamentum nuchæ. From this a median crest extends
toward the foramen magnum, and laterally two lines (Lineæ nuchæ
superiores) curve outward, marking the upper limit of the area which is
roughened for muscular attachment. The surface above the lines is
relatively smooth, and is covered only by the skin and the thin
auricular muscles in the living animal. It is separated from the cranial
roof by a thick border, which forms centrally the frontal eminence, and
bears at its extremities the processus cornu—except in the polled
breeds. The condyles are further apart, and the articular surfaces are
more clearly divided into upper and lower parts than in the horse.
[Illustration:
FIG. 95.—CROSS-SECTION OF SKULL OF OX. SECTION PASSES THROUGH FIFTH
CHEEK TOOTH.
]
[Illustration:
FIG. 96.—CROSS-SECTION OF SKULL OF OX. SECTION PASSES THROUGH SECOND
CHEEK TOOTH.
_a_, _b_, _c_, Superior, middle, inferior meatus; _b′_, communication
between middle meatus and cavity of upper part of inferior turbinal;
_c′_, communication between inferior meatus and lower part of
inferior turbinal; _d_, cavity of superior turbinal; _e_, _f_, outer
and inner walls of _d_; _g_, _h_, upper and lower cavities of
inferior turbinal bone; _i_, basal lamella of inferior turbinal;
_i′_, _i″_, upper and lower divisions of inferior turbinal bone;
_k_, floor of nasal cavity; _m_, lacrimal sinus; _n_, maxillary
sinus; _p_, palatine sinus; _q_, septum between maxillary and
palatine sinuses; _r_, infraorbital canal; _s_, septum between
palatine sinuses; _t_, common meatus; _u_, naso-lacrimal canal; _v_,
floor of nasal cavity and roof of palatine sinus; _1_, septum nasi;
_2_, posterior part of second cheek tooth; _3_, posterior part of
fifth cheek tooth; _4_, hard palate. (After Ellenberger, in
Leisering’s Atlas.)
]
The =cranial cavity= is shorter and its long axis is more oblique than
in the horse, but it is relatively high and wide. The anterior fossa
lies at a much higher level than the rest of the floor. The olfactory
fossæ are smaller, and the sella turcica is much deeper than in the
horse. A deep groove leads from the petrous temporal forward over the
foramen ovale to the foramen rotundum. Behind the sella there is often a
distinct prominence (Dorsum sellæ). The internal sagittal crest is
prominent anteriorly, but absent further back. A faintly marked
elevation takes the place of the tentorium osseum. The small petrous
temporal bone projects into the cavity laterally. The ridges and digital
impressions are very pronounced. The parieto-temporal canal is formed
entirely in the temporal bone, and opens at the apex of the petrous,
where it is joined by the condyloid canal. The foramen lacerum is
divided into two parts (For. lacerum anterius et posterius).
The =nasal cavity= is incompletely divided by the septum, which does not
reach the floor posteriorly. The floor is relatively long, and is more
concave from side to side than in the horse. In the dry skull it has a
large oval opening into the palatine sinus, which is closed during life
by mucous membrane. The middle meatus is divided behind into upper and
lower branches by the great ethmoturbinal. The posterior nares are
narrow and oblique.
[Illustration: