The =malar= or =zygomatic bones= (Ossa zygomatica) are placed between
the lacrimal above and the maxilla below and in front. Each is
irregularly triangular in outline and presents three surfaces, three
borders, a base, and an apex.
The =facial surface= is smooth, slightly convex, wide in front, and
narrow behind. At its lower part it presents the =facial= or =zygomatic
crest=, which is continuous in front with the similar ridge on the
maxilla and behind with the zygomatic process of the temporal; the crest
is rough below, where the masseter muscle is attached to it.
The =orbital surface= is separated from the facial surface by the
concave =orbital margin=. It is concave and smooth, and forms part of
the lower and front wall of the orbit.
The =nasal surface= is concave and faces into the maxillary sinus. In
the young foal a considerable part of it articulates with the maxilla.
The =superior border= articulates with the lacrimal chiefly, but to a
small extent behind with the maxilla also.
The =inferior border= and the =base= articulate with the maxilla.
The =apex= is beveled above and is overlapped by the zygomatic process
of the temporal bone.
=Development.=—Each ossifies in membrane from one or two centers.