Nerve supply of teeth

Nerve supply of teeth

Trigeminal nerve

The trigeminal nerve is the largest cranial nerve (Fig. A).

It leaves the anterior aspect of the pons as a small motorroot and a large sensory root, and it passes forward, out ofthe posterior cranial fossa, to reach the apex of the petrouspart of the temporal bone in the middle cranial fossa. Here,the large sensory root expands to form the trigeminalganglion(Fig. A).

The trigeminal ganglion lies within a pouch of dura mater called the trigeminalcave.

The motor root of the trigeminal nerve is situated below the sensory ganglion and is completely separate from it. The ophthalmic (V1), maxillary (V2), and mandibular (V3) nerves arise from the anterior border of the ganglion (Fig. A).

Figure (A) Branches of trigeminal nerve

Maxillary Nerve 

The maxillary nerve arises from the trigeminal ganglion inthe middle cranial fossa.

It passes forward in the lateral wall of the cavernous sinus and leaves the skull through the foramen rotundum and crosses the pterygopalatine fossa to it enter the orbit through the inferior orbital fissure. It then continues as the infraorbital nerve in the infraorbital groove, and emerges on the face throughthe infraorbital foramen. It gives sensory fibers to the ski of the face and the side of the nose.

Figure (B) Branches of maxillary nerve

Branches

• Meningeal branches
• Zygomatic branch, which divides into thezygomaticotemporal and the zygomaticofacial nervesthat supply the skin of the face. The zygomaticotemporalbranch gives parasympathetic secretomotor fibers tothe lacrimal gland via the lacrimal nerve.
• Ganglionic branches, which are two short nerves thatsuspend the pterygopalatine ganglion in the pterygopalatinefossa. They contain sensory fibersthat have passed through the ganglion from the nose,the palate, and the pharynx. They also contain postganglionicparasympathetic fibers that are going to the lacrimalgland.
• Posterior superior alveolar nerve (Fig. B), whichsupplies the maxillary sinus as well as the upper molarteeth and adjoining parts of the gum and the cheek
• Middle superior alveolar nerve (Fig. B), which suppliesthe maxillary sinus as well as the upper premolarteeth, the gums, and the cheek
• Anterior superior alveolar nerve (Fig. B), whichsupplies the maxillary sinus as well as the upper canineand the incisor teeth
• Pterygopalatine Ganglion
• The pterygopalatine ganglion is a parasympathetic ganglion,which is suspended from the maxillary nerve in thepterygopalatine fossa. It is secretomotor to thelacrimal and nasal glands.
• Branches
• Orbital branches, which enter the orbit through theinferior orbital fissure
• Greater and lesser palatine nerves, whichsupply the palate, the tonsil, and the nasal cavity
• Pharyngeal branch, which supplies the roof of thenasopharynx

Mandibular Nerve 

The mandibular nerve is both motor and sensory (Figs.11.11 and 11.65). The sensory root leaves the trigeminalganglion and passes out of the skull through the foramenovale to enter the infratemporal fossa. The motor root ofthe trigeminal nerve also leaves the skull through the foramenovale and joins the sensory root to form the trunk ofthe mandibular nerve, and then divides into a small anteriorand a large posterior division (Fig. 11.66).

Branches from the Main Trunk of the Mandibular Nerve

• Meningeal branch
• Nerve to the medial pterygoid muscle, which suppliesnot only the medial pterygoid, but also the tensor velipalatini muscle.
• Branches from the Anterior Division of theMandibular Nerve
• Masseteric nerve to the masseter muscle
• Deep temporal nerves to the temporalis muscle
• Nerve to the lateral pterygoid muscle
• Buccal nerve to the skin and the mucous membrane ofthe cheek (Fig. A). The buccal nerve does not supplythe buccinator muscle (which is supplied by the facialnerve), and it is the only sensory branch of the anteriordivision of the mandibular nerve.
• Branches from the Posterior Division of theMandibular Nerve
• Auriculotemporal nerve, which supplies the skin of theauricle (Fig. A), the external auditory meatus, thetemporomandibular joint, and the scalp. This nerve alsoconveys postganglionic parasympathetic secretomotorfibers from the otic ganglion to the parotid salivarygland.
• Lingual nerve, which descends in front of the inferioralveolar nerve and enters the mouth (Fig. A). It then runs forward on the side of the tongueand crosses the submandibular duct. In its course, it isjoined by the chorda tympani nerve,and it supplies the mucous membrane of theanterior two thirds of the tongue and the floor of themouth.
• It also gives off preganglionic parasympatheticsecretomotor fibers to the submandibular ganglion.
• Inferior alveolar nerve (Fig. A), whichenters the mandibular canal to supply the teeth of thelower jaw and emerges through the mental foramen(mental nerve) to supply the skin of the chin. Before entering the canal, it gives off the mylohyoidnerve, which supplies the mylohyoidmuscle and the anterior belly of the digastricmuscle.
• Communicating branch, which frequently runs fromthe inferior alveolar nerve to the lingual nerveThe branches of the posterior division of the mandibularnerve are sensory (except the nerve to the mylohyoid muscle).

DENTAL PAIN PATHWAY

Otic Ganglion

The otic ganglion is a parasympathetic ganglion that islocated medial to the mandibular nerve just below theskull, and it is adherent to the nerve to the medial pterygoidmuscle. The preganglionic fibers originate in the glossopharyngealnerve, and they reach the ganglion via thelesser petrosal nerve. The postganglionicsecretomotor fibers reach the parotid salivary gland via theauriculotemporal nerve. (Fig. A)

C L I N I C A L N O T E S

Injury to the Lingual Nerve:

The lingual nerve passes forward into the submandibularregion from the infratemporal fossa by running beneath theorigin of the superior constrictor muscle, which is attachedto the posterior border of the mylohyoid line on the mandible.Here, it is closely related to the last molar tooth and is liableto be damaged in cases of clumsy extraction of an impactedthird molar