Face

The face (facies) refers to the anterior part of the head, which contains the nasal and oral cavities. Externally, it shows the regions of the nose, mouth, chin, mandible, and, on each side, those of the eye, the zygomatic arch, and the cheek.

• The nasal region corresponds to the nose. It includes several subdivisions: the bridge of the nose, the tip of the nose, and the nostrils. The bridge of the nose extends rostrally from the forehead at the level of the eyes. It continues laterally into the infraorbital and cheek regions, and rostrally into the tip of the nose. Its profile varies with species and breeds. It includes a median part, corresponding to the dorsum of the nose, and two lateral surfaces. The tip of the nose is bordered by the nostrils, ending rostrally the bridge of the nose and overhanging the upper lip, with which it forms the rostrum.

• The mouth, externally, is only the opening of the oral cavity proper, which contains the teeth and the tongue. It is a transverse slit closed by two lips, one upper and one lower, which join on each side at a commissure, limiting the angle of the mouth.

• The chin generally forms a simple muscular prominence.

• The mandibular region, laterally hidden by the cheek, extends caudally from the chin and widens. The lower border of the mandibular body forms a projection on each side. These two projections frame a large space, the intermandibular region, which extends to the throat. The lower border of the mandible ends caudally at the angle of the jaw.

• The orbital region is located rostrally and laterally to the forehead; externally, it corresponds to the eye. Its anatomical basis is the eyeball, housed with its accessory muscles and lacrimal apparatus within the orbital cavity. The eye is protected by two eyelids, one upper and one lower.

• The zygomatic region is located more caudally beneath the orbital region and extends to the base of the ear. It ends, below and in front of the ear, with a prominence corresponding to the temporomandibular joint.

• The cheek extends from the commissure of the lips to the parotid region. It is bounded dorsally by the zygomatic, infraorbital, and nasal regions, and ventrally by the mandibular ramus. It has two distinct parts: caudally, the flat part of the cheek or masseteric region, based on the masseter muscle; rostrally, the buccal region, formed mainly by the buccinator muscle.

The face is much more developed in animals than in humans. In ungulates, it occupies more than two-thirds of the head.