Supra-angular and coronoid splint-bones serve for the insertion of part of the temporal or masseter muscle.
Its duct leaves the inferior anterior angle, at first descends a little, and runs forward under cover of the rounded inferior border of the lower jaw, then curves up along the anterior margin of the masseter muscle, becoming superficial, pierces the buccinator, and enters the mouth by a simple aperture opposite the middle of the crown of the third premolar tooth.
The masseter muscle does not pass through the narrow infra-orbital canal, and the temporal muscle is large.
The lachrymal forj amen is always within the orbital margin; and in many species the infra-orbital foramen is very large (in some as large as the orbit) and transmits part of the masseter muscle.
Zygomatic arch, the middle portion of which is formed by the more or less straight and horizontal jugal, and the large infra-orbital canal, traversed by a portion of the masseter muscle.
The lower jaw is large, especially the region of the angle, which is expanded and flattened, giving great surface for the attachment of the masseter muscle.
T, temporal muscle; m, masseter; m', portion of masseter transmitted through the infra-orbital foramen, the superior maxillary nerve passing outwards between it and the maxilla.