Trigeminal Nerve: Mandibular Branch (V3)

• The trigeminal nerve’s mandibular branch (V3) is covered in these notes
• This will describe the role, regions supplied and relevance to dentistry, relative to the mandibular branch of the trigeminal nerve (CN V3)

Trigeminal Nerve

• It is the largest cranial nerve
• Knowledge of this nerve is important for dental professionals
• The trigeminal nerve has three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3)

Mandibular Branch (V3)

• It is the largest of the trigeminal nerve's three divisions
• This branch exits the skull through the foramen ovale
• It contains both sensory and motor fibers

Sensory Supply

• Provides sensation to the mandibular teeth and supporting structures
• Innervates the mucosa of the anterior two-thirds of the tongue and the floor of the mouth
• Supplies the skin of the lower face, parts of the temporal region, and the outer ear

Motor Supply

• Controls the muscles of mastication
• Innervates the mylohyoid muscle
• Supplies the anterior belly of the digastric muscle
• Controls the tensor veli palatini and tensor tympani muscles

Anatomical Course

• It divides into small anterior and larger posterior trunks shortly after exiting the skull
• Branches exist from the primary nerve before it divides

Branches before division

• Supplies the meningeal branch
• Nerve extends to the medial pterygoid muscle

Anterior Trunk Branches

• Masseteric nerve supplies the masseter muscle
• Deep temporal nerves supply the temporalis muscle
• Nerve to the lateral pterygoid muscle
• Long buccal nerve provides sensory innervation to the cheek

Posterior Trunk Branches

• Auriculotemporal nerve provides sensory innervation to the temporal region
• Lingual nerve provides sensory innervation to the tongue
• Inferior alveolar nerve supplies the mandibular teeth

Medial Pterygoid Nerve

• A motor nerve that enters the deep surface of the medial pterygoid muscle
• It also supplies the tensor tympani and tensor veli palatini muscles
• Elevates the jaw

Masseter Muscle

• The masseteric nerve, the first branch of the anterior trunk, innervates it
• The nerve crosses the masseter muscle between the coronoid process and the condyle of the mandible
• There is an articular branch to the temporomandibular joint (TMJ)
• Action: Elevates the mandible (mouth closing)

Temporalis Muscle

• Anterior and deep temporal nerves innervate this
• Action: Elevates the mandible (mouth closing)

Lateral Pterygoid Muscle

• Nerve to the lateral pterygoid may run partly with the long buccal nerve
• Depresses the mandible (mouth opening)

Long Buccal Nerve

• Exclusively a sensory nerve and anterior trunk branch
• The nerve emerges between the heads of the lateral pterygoid muscle
• It runs close to the retromolar fossa of the mandible on the lateral surface of the buccinator muscle in the cheek
• It provides branches to the skin of the cheek
• Pierces the buccinator muscle to supply the buccal sulcus and buccal gingivae of mandibular molars and premolars

Auriculotemporal Nerve

• The first branch of the posterior trunk is sensory
• Autonomic fibers extend to the parotid gland
• The nerve merges with the chorda tympanic branch of the facial nerve
• It travels behind the lateral pterygoid muscle in between the condyle and sphenomandibular ligament
• Emerges between the TMJ and the external auditory meatus and ascends on the side of the head

Lingual Nerve

• This is the posterior trunk’s second branch and is sensory
• It joins the chorda tympani branch of the facial nerve
• Receives parasympathetic fibers for the submandibular and sublingual glands
• Emerges from under the lateral pterygoid muscle
• Curves down and forward between the mandibular ramus and medial pterygoid muscle
• Lies anterior, but deeper than the inferior alveolar nerve, towards the floor of the mouth

Lingual Nerve Supply

• Mucosa covers the anterior two-thirds of the tongue’s dorsum
• Innervates the undersurface of the tongue and the floor of the mouth
• Innervates the lingual gingivae of mandibular teeth
• It twists around the submandibular duct and enters the tongue behind the sublingual salivary gland

Inferior Alveolar (Dental) Nerve

• It is sensory and motor
• Descends deep to the lateral pterygoid muscle, positioning itself behind the lingual nerve
• Enters the mandibular foramen
• Proceeds through the mandibular canal
• Divides near the premolars into the mental and incisive nerves
• The mental nerve emerges at the mental foramen
• The mental nerve travels anteriorly in the incisive canal

Mylohyoid Nerve

• It is a branch of the inferior alveolar nerve
• It branches off just before the mandibular foramen
• The nerve runs in the mylohyoid groove
• Supplies motor function
• Extends to the mylohyoid muscle and the anterior belly of the digastric muscle
• Depresses the mandible (on a fixed hyoid) or elevates the hyoid during swallowing

Inferior Alveolar Nerve Branches

• The inferior alveolar nerve supplies the mandibular molars and premolars, including gingivae
• Supplies skin of the chin, lower lip, and labial gingivae of the anterior mandibular teeth (Mental Nerve)
• Incisive nerve innervates the mandibular incisors and canines

Summary of the Mandibular Branch

• The mandibular branch supplies the mandibular teeth and supporting structures
• Supplies the mucosa of the anterior two-thirds of the tongue and floor of the mouth
• Innervates the muscles of mastication
• The trigeminal nerve is the largest and the fifth cranial nerve
• The trigeminal nerve has three divisions: ophthalmic, maxillary, and mandibular
• The mandibular nerve exits through the foramen ovale