Head and Neck Anatomy
Scope
Head and neck anatomy is examined through nerve and vessel pathways, fascial spaces, and the applied anatomy that determines where a local anaesthetic is deposited and which structures a surgical flap can injure.
Trigeminal (V)
- V1 exits the superior orbital fissure; branches are frontal, lacrimal and nasociliary.
- V2 exits the foramen rotundum; infraorbital, zygomatic, greater and lesser palatine, nasopalatine, posterior superior alveolar.
- V3 exits the foramen ovale; sensory branches are lingual, inferior alveolar, buccal and auriculotemporal, with motor supply to the muscles of mastication plus mylohyoid, anterior digastric, tensor veli palatini and tensor tympani.
Arteries
External carotid branches in order: superior thyroid, ascending pharyngeal, lingual, facial, occipital, posterior auricular, maxillary, superficial temporal. The maxillary artery gives off the middle meningeal, inferior alveolar and posterior superior alveolar arteries.
Applied landmarks
- The lingual nerve lies medial to the lingula and retromolar triangle, so lingual retraction protects it during mandibular surgery.
- The inferior alveolar nerve enters the mandibular foramen; a bifid canal or accessory supply explains some failed anaesthetics.
- The facial nerve exits the stylomastoid foramen; its buccal branch crosses the masseter and is at risk in a buccal incision.
Worked example
A lesion at the foramen ovale produces numbness of the lower lip, chin and anterior two-thirds of the tongue, and the jaw deviates to the same side on opening. Reasoning: V3 carries lingual and inferior alveolar sensory fibres and motor fibres to the lateral pterygoid; with that muscle paralysed, the contralateral pterygoid acts unopposed.
Traps
- The buccal nerve of V3 is sensory; the buccal branch of the facial nerve is motor.
- Taste from the posterior third of the tongue travels with the glossopharyngeal nerve, not the lingual.