Trigeminal nerve (Maxillary)

• The trigeminal nerve is the largest cranial nerve.
• Understanding this nerve is crucial for dental professionals.
• The nerve splits into 3 divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3).

Nerve Roots

• Each nerve has a short trunk with two closely adapted roots.
• The motor root is thinner.
• The sensory root is thicker.
• Trigeminal nerves enable sensing facial touch, pain and temperature.
• Trigeminal nerves facilitate control of muscles for chewing.
• It should be distinguished from the facial nerve (cranial nerve VII), which controls all other facial movements

Areas Supplied

• Sensory (afferent) roots supply maxillary dentition, mandibular dentition, skin of face and head, oral mucosa, nasal mucosa, air sinuses, and meninges.
• Motor (efferent) roots supply the muscles of mastication: masseter, temporalis, medial pterygoid, lateral pterygoid, and the anterior belly of digastric.
• Motor (efferent) roots supply mylohyoid, tensor tympani, and tensor veli palatini.
• The Trigeminal nerve originates in the brain stem and arises from the pons.
• There is one motor nucleus and 3 sensory nuclei in the Pons.

Pathway from Skull

• From the middle cranial fossa, the 3 branches of the trigeminal nerve exit at the superior orbital fissure (SOF), foramen rotundum (FR), and foramen ovale (FO)
• The ophthalmic branch enters the orbit through the superior orbital fissure (SOF).
• The maxillary branch exits via foramen rotundum (FR) into pterygopalatine fossa, then through infra-orbital canal to the infra-orbital foramen. The mandibular branch exits via foramen ovale (FO).
• The three divisions of the trigeminal nerve merge in an area called the Gasserion ganglion.
• Within the brain stem, signals traveling via the trigeminal nerve reach specialized neuron clusters called the trigeminal nerve nucleus.

Ophthalmic Nerve (V1)

• V1 is the first division of the sensory root of the trigeminal nerve.
• It carries information to the brain via the superior orbital fissure of the sphenoid bone.
• Cranial nerves II, IV, and VI also traverse the superior orbital fissure.
• It is the smallest division, serving as an afferent nerve to the conjunctiva, cornea, eyeball, orbit, forehead, ethmoidal and frontal sinuses, and portions of the dura mater.
• The branches of ophthalmic nerve are the lacrimal nerve, frontal nerve, and nasociliary nerve.
• The lacrimal nerve supplies conjunctiva and skin covering lateral part of upper eyelid and is responsible for tear production.
• The Frontal nerve supplies mucous membrane lining frontal sinus plus skin & conjunctiva covering the upper eyelid & skin over the forehead & scalp.
• The nasociliary nerve has sensory branches to the ciliary ganglion, long ciliary nerves, posterior ethmoidal nerve, anterior ethmoidal nerve, and infratrochlear nerve

Pterygo-Maxillary Fissure

• It lies between posterior surface of the maxilla & pterygoid process of sphenoid bone.
• It fills the triangular gap between the lower ends of medial & lateral pterygoid plates.
• The pterygomaxillary fissure (C) leads into it.
• It is entered by foramen rotundum & maxillary nerve.

Maxillary Nerve (V2)

• The maxillary branch exits via foramen rotundum and passes into the upper part of the pterygopalatine fossa which divides into zygomatic, infraorbital, posterior superior alveolar, and pterygopalatine nerves.
• V2 consists of only sensory fibers.
• V2 is the nerve of the maxillary process on the embryonic face.
• It supplies maxillary teeth and supporting structures, the hard and soft palate, the maxillary sinus, much of the nasal cavity and skin overlying middle part of face.

Infra-Orbital Nerve

• The infra-orbital is the terminal branch of the maxillary nerve
• It enters the orbit at the inferior orbital fissure and runs in the infra orbital groove.
• It leaves the orbit at infra-orbital foramen to run onto the face.
• Its branches are middle superior alveolar nerve, anterior superior alveolar nerve and terminal branches being palpebral, nasal & labial nerves.
• The terminal branches of the nerve arise at the infraorbital foramen.
• The palpebral nerve branch supplies skin of the lower eyelid.
• The nasal nerve branch supplies skin of side of nose.
• The labial nerve supply skin & oral mucosa of the upper lip, the labial gingivae of anterior maxillary teeth, and skin of cheek overlying the body of the maxilla.

Posterior Superior Alveolar Nerve (C)

• It leaves the pterygopalatine fossa through the pterygomaxillary fissure.
• It runs onto tuberosity of maxilla, sending branch to supply buccal gingiva of maxillary molars.
• This nerve pierces bone to supply maxillary sinus & maxillary molar teeth 3rd, 2nd & palatal & disto-buccal root of 1st.

Middle & Anterior Superior Alveolar Nerves (G)

• The middle & anterior superior alveolar nerves arise from the infra-orbital nerve in the orbit.
• The middle supplies the maxillary premolars & the mesio-buccal root of the first maxillary molar.
• The anterior supplies the maxillary incisors & canine.

Pterygopalatine Nerves

• The 3 Pterygopalatine nerves are the Greater Palatine, Lesser Palatine and Nasopalatine.
• The greater palatine passes through greater palatine canal & onto hard palate at the greater palatine foramen.
• It gives off nasal branches in canal that supplies mucosa of lateral wall of nasal fossa.
• On palate, it supplies much of mucosa of the hard palate & palatal gingivae, except round incisive papilla.
• The lesser palatine passes through greater palatine canal to lesser palatine foramen.
• It supplies the soft palate.
• The nasopalatine, enters nasal cavity through sphenopalatine foramen, supplies part of nasal septum, and passes through incisive canal on hard palate.
• The nasopalatine nerve supplies oral mucosa around incisive papilla.

Zygomatic nerve

• The Zygomatic Nerve travels anteriorly to enter orbit via inferior orbital fissure.
• It divides into the Zygomaticotemporal nerve and the Zygomaticofacial nerve.
• The zygomaticotemporal nerve Provides sensory innervation to the temple.
• The zygomaticofacial nerve emerges on the face through zygomaticofacial foramen, perforating orbicularis oculi & innervates skin on the prominence of the cheeks.