Oral and Maxillofacial Anatomy, Physiology, and Histology
What the exam expects
This domain tests your spatial and histological knowledge of the oral and maxillofacial region. You should be able to trace the trigeminal branches, describe the course of the facial nerve, identify the muscles of mastication and facial expression, and recognize the histology of enamel, dentin, pulp, cementum, and periodontal ligament.
Concepts to master
- Trigeminal nerve: V1 (ophthalmic), V2 (maxillary), V3 (mandibular). The inferior alveolar nerve is a branch of V3 and supplies the mandibular teeth; the lingual nerve carries general sensation and chorda tympani fibers for taste to the anterior two-thirds of the tongue.
- Facial nerve: motor to the muscles of facial expression; chorda tympani carries taste from the anterior tongue; the nerve exits the stylomastoid foramen.
- Muscles of mastication: masseter, temporalis, medial pterygoid, lateral pterygoid; all are innervated by V3.
- Dental histology: enamel is acellular and cannot regenerate; dentin is produced by odontoblasts; cementum is produced by cementoblasts; the periodontal ligament anchors the tooth to alveolar bone.
Traps
A common trap is confusing the lingual nerve (sensation and taste) with the inferior alveolar nerve (sensation to teeth and chin). Another is confusing the facial nerve (expression) with the trigeminal nerve (mastication and sensation).
Worked rule of thumb
When a lesion affects the corner of the mouth and eye closure, think facial nerve (peripheral). When it affects only the lower face, think central lesion or trigeminal branch. Use the "forehead sparing" rule: upper motor neuron lesions spare the forehead because it has bilateral cortical input.
Study strategy
Draw the trigeminal and facial nerve branches from memory weekly. Label the dental tissues on a histology slide and state which cell produces each layer.