Oral and Maxillofacial Anatomy
This domain tests applied regional anatomy of the head and neck as you use it chairside: trigeminal branches that determine whether a block works, masticatory muscle and temporomandibular joint mechanics, the fascial spaces that predict how an odontogenic infection spreads, and the vascular and lymphatic anatomy behind surgical bleeding risk and oncology referral.
Trigeminal branches that decide anaesthetic success
- V1 (ophthalmic): supraorbital, supratrochlear and nasociliary branches supply the forehead, upper eyelid and anterior nasal skin.
- V2 (maxillary): infraorbital, zygomatic, greater and lesser palatine, nasopalatine, and the posterior, middle and anterior superior alveolar nerves. The nasopalatine nerve supplies the anterior hard palate and palatal gingiva of anterior teeth.
- V3 (mandibular): auriculotemporal, buccal, lingual and inferior alveolar. The inferior alveolar gives off the nerve to mylohyoid before entering the mandibular foramen and terminates as the mental nerve at the mental foramen, usually between the premolars.
- The buccal nerve (V3) supplies the buccal gingiva and mucosa beside the mandibular molars - not the molar teeth themselves - and is not anaesthetised by an inferior alveolar block.
Muscles and joint mechanics
Masseter, temporalis and medial pterygoid elevate the mandible; the lateral pterygoid is the principal depressor and protrusor, and its superior head inserts into the disc and capsule. Posterior temporalis fibres retract the condyle.
Spread of odontogenic infection
Maxillary lateral incisor and canine infections track to the canine space; maxillary molars to the buccal and infratemporal spaces; mandibular molars to the submandibular and then sublingual and submental spaces, where bilateral involvement defines Ludwig angina.
Worked example
A patient reports persistent buccal mucosal pain after an otherwise successful inferior alveolar block for a mandibular first molar extraction. Reasoning: the block anaesthetises the inferior alveolar, incisive and usually lingual nerves; the buccal soft tissue beside the molars is served by the long buccal nerve, which runs outside the pterygomandibular space. The correct supplement is a local infiltration buccally, not a repeat block.
Traps that cost marks
- Assuming an inferior alveolar block always anaesthetises the lingual nerve; accessory supply from the mylohyoid nerve can also explain failed molar anaesthesia.
- Confusing the mental nerve (lower lip and chin) with the buccal nerve.
- Forgetting that the maxillary sinus floor lies close to the apices of upper molars and premolars, and that the greater palatine artery runs forward from the greater palatine foramen - a bleeding hazard in palatal flaps.
- Ignoring the retropharyngeal space as the route from a dental infection to mediastinitis.