The sharply angled boundary between the lateral and inferior surfaces of the greater wing is the infratemporal crest (Fig. 8.136). Two apertures (the foramen ovale and the foramen spinosum) pass through the base of the greater wing and allow the mandibular nerve [V3] and the middle meningeal artery, respectively, to pass between the middle cranial fossa and infratemporal fossa. In addition, one or more small sphenoidal emissary foramina penetrate the base of the greater wing anteromedial to the foramen ovale and allow emissary veins to pass between the pterygoid plexus of veins in the infratemporal fossa and the cavernous sinus in the middle cranial fossa.
Projecting vertically downward from the greater wing immediately medial to the foramen spinosum is the irregularly shaped spine of the sphenoid, which is the attachment site for the cranial end of the sphenomandibular ligament.
The lateral plate of the pterygoid process is a vertically oriented sheet of bone that projects posterolaterally from the pterygoid process (Fig. 8.136). Its lateral and medial surfaces provide attachment for the lateral and medial pterygoid muscles, respectively.
The posterior surface of the maxilla contributes to the anterior wall of the infratemporal fossa (Fig. 8.136). This surface is marked by a foramen for the posterosuperior alveolar nerve and vessels. The superior margin forms the inferior border of the inferior orbital fissure.
The zygomatic bone is a quadrangular-shaped bone that forms the palpable bony prominence of the cheek:
A maxillary process extends anteromedially to articulate with the zygomatic process of the maxilla.
A frontal process extends superiorly to articulate with the zygomatic process of the frontal bone.
A temporal process extends posteriorly to articulate with the zygomatic process of the temporal bone to complete the zygomatic arch.
A small zygomaticofacial foramen on the lateral surface of the zygomatic bone transmits the zygomaticofacial nerve and vessels onto the cheek.
A thin plate of bone extends posteromedially from the frontal process and contributes to the lateral wall of the orbit on one side and the anterior wall of the temporal fossa on the other. A zygomaticotemporal foramen on the temporal fossa surface of the plate where it attaches to the frontal process is for the zygomaticotemporal nerve.
Ramus of mandible
The ramus of the mandible is quadrangular in shape and has medial and lateral surfaces and condylar and coronoid processes (Fig. 8.137).
The lateral surface of the ramus of the mandible is generally smooth except for the presence of a few obliquely oriented ridges. Most of the lateral surface provides attachment for the masseter muscle.
The posterior and inferior borders of the ramus intersect to form the angle of the mandible, while the superior border is notched to form the mandibular notch. The anterior border is sharp and is continuous below with the oblique line on the body of the mandible.
The coronoid process extends superiorly from the junction of the anterior and superior borders of the ramus. It is a flat, triangular process that provides attachment for the temporalis muscle.
The condylar process extends superiorly from the posterior and superior borders of the ramus. It consists of: the head of the mandible, which is expanded medially and participates in forming the temporomandibular joint; and the neck of the mandible, which bears a shallow depression (the pterygoid fovea) on its anterior surface for attachment of the lateral pterygoid muscle.
The medial surface of the ramus of the mandible is the lateral wall of the infratemporal fossa (Fig. 8.137B). Its most distinctive feature is the mandibular foramen, which is the superior opening of the mandibular canal. The inferior alveolar nerve and vessels pass through this foramen.