The unpaired frontal bone forms the forehead and superior margins of the orbits. (The orbital walls are discussed later).
The paired maxillae form the upper jaw, the medial and inferior margins of the orbits, and the lateral and inferior margins of the anterior nasal aperture. (The nasal walls are described later).
The paired nasal bones form the bridge of the nose and the superior margins of the anterior nasal aperture.
The paired zygomatic bones form the prominences of the cheeks and the inferior and lateral margins of the orbits.
The unpaired mandible forms the lower jaw and the chin (mental prominence).
The unpaired ethmoid bone forms the upper part of the bony nasal septum.
The unpaired vomer forms the lower part of the bony nasal septum.
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NEUROVASCULAR EXIT PORTALS:
The supraorbital notch (in some skulls this is a foramen) transmits the supraorbital nerve and vessels. The nerve is a branch of the frontal nerve, which belongs to the ophthalmic division of the trigeminal nerve (V1). The artery is derived from the ophthalmic artery, a branch of the internal carotid; the vein drains to the superior ophthalmic vein and thence to the cavernous sinus.
The infraorbital foramen transmits the infraorbital nerve and vessels. The nerve is a branch of the maxillary division of the trigeminal nerve (V2). The artery is a branch from the 3rd part of the maxillary artery, a terminal branch of the external carotid; the vein drains to the pterygoid venous plexus and thence to the maxillary vein.
The zygomaticofacial foramen (missing in some skulls, multiple in others) transmits the zygomaticofacial nerve and vessels. The nerve arises from the infraorbital branch of the maxillary division of the trigeminal nerve (V2). The artery is a branch from the 3rd part of the maxillary artery and belongs to the external carotid system; the vein drains to the pterygoid venous plexus and thence to the maxillary vein.
The mental foramen transmits the mental nerve and vessels, which are continuations of the inferior alveolar neurovascular bundle. The nerve is therefore a branch of the mandibular division of the trigeminal (V3). The artery is a branch of the maxillary artery from the external carotid; the vein drains to the maxillary vein.
Prominent Landmarks and Reference Points:
The superciliary ridges (L. supercilia=eyebrow) of the frontal bone lie just above the superior orbital margins. They vary from individual to individual but generally are more prominent in males than females.
Glabella (L. glaber=smooth, bald) is the smooth median elevation of the frontal bone linking the superciliary ridges.
The frontal tuberosities are elevations of the frontal bone above the superciliary ridges. They vary from individual to individual.
Nasion (L. nasus=nose) is the point of intersection of the internasal and frontonasal sutures.
The anterior nasal spine marks the union of left and right maxillae. It can be palpated easily on the midline in the lower part of the nasal septum.