_a_, Right ramus; _b_, left ramus; _c_, body; _d_, alveolar border;
_e_, processus angularis; _f_, condyle; _g_, coronoid process; _h_,
masseteric fossa; _i_, _k_, crests which form the upper and lower
boundaries of fossa; _l_, mandibular foramen; _m_, mental foramina;
_n_, masseteric line; _o_, sigmoid notch. (Ellenberger-Baum, Anat.
d. Hundes.)
]
The large zygomatic process constitutes the bulk of the =malar bone=. It
is very long and is strongly curved. The upper border is convex, free in
front, where it forms part of the orbital margin, beveled behind for
articulation with the similar process of the temporal bone. Between
these it bears an eminence, the processus frontalis, to which the
orbital ligament is attached. The body of the bone may be considered to
consist of a =lacrimal process= directed upward and fitting in between
the lacrimal and maxilla, and a =maxillary process= directed downward.
The facial surface is convex.
The =superior turbinal bone= is in its anterior part a simple plate,
attached by one edge to the nasal bone; it curves downward and inward,
and its free border is thickened and everted. The posterior part is
wider and resembles the ethmoturbinals, with which it is connected.
The =inferior turbinal bone= is short and very complex. It is attached
to the nasal surface of the maxilla by a basal lamina, which divides
into two secondary lamellæ. The latter detach numerous tertiary lamellæ,
which are coiled and have thick free edges (Fig. 373).
The =vomer= is not in contact with the posterior part of the floor of
the nasal cavity, and does not divide the posterior nares. The posterior
end is narrow and deeply notched. Near the posterior nares the two
plates curve outward and join the palate bones and assist in forming the
lamina transversalis.
The two halves of the =mandible= do not fuse completely even in old age.
The body presents six alveoli for the incisor teeth and two for the
canines. The incisor alveoli increase in size from first to third. The
canine alveoli extend deeply downward and backward. There are usually
two or more foramina on the mental surface. The rami diverge less than
in the pig. The inferior border of the horizontal part is convex in its
length and is thick and rounded. The alveolar border slightly concave in
its length and is a little everted, especially in its middle; it
presents seven alveoli for the lower cheek teeth, which resemble those
of the upper jaw except that the fourth and sixth are much smaller and
the fifth is like the fourth of the upper series. The interalveolar
space is very short or even absent. There are two or three mental
foramina on either side. The vertical part is relatively small. Its
external surface presents a deep =masseteric fossa= which encroaches on
the coronoid process and is limited by ridges in front and below. The
internal surface is convex and is marked by the usual foramen. At about
the same level as the latter is the rough =angular process= (Processus
angularis), which projects backward from the posterior border, and is
equivalent to the angle of the other animals. The condyle is placed very
low—not much higher than the apex of the canine tooth when the bone is
resting on a flat surface. It is long transversely and the inner part of
the articular surface is much the wider and extends over the posterior
surface. Its long axis is a little oblique, the inner end being inclined
somewhat downward and forward. The coronoid process is very extensive
and is bent slightly outward and backward.
The body of the =hyoid bone= is a slightly curved transverse rod; it is
compressed from before backward, and bears no lingual process. The
thyroid cornua are permanently attached to the body by cartilage; they
diverge widely, curve inward, and are compressed laterally. The small
cornua are short, prismatic, and strong. The middle cornua are commonly
a little longer than the great cornua; they are compressed laterally,
and are slightly enlarged at the ends, which are joined by cartilage to
the adjacent cornua. The great cornua are bent outward and are somewhat
twisted.