**2. Anatomy**

Management of pain in dentistry requires knowledge about the fifth cranial nerve anatomythe trigeminal nerve. It is the largest of the cranial nerves and has three major divisions: ophthalmic, maxillary and mandibular.

**The trigeminal nerve** is the major sensory nerve of the face containing both motor fibers for masticatory muscles and sensory fibers. This nerve exits the brain through the area between the pons and the middle cerebellar peduncles.

**The ophthalmic branch** runs through the lateral wall of the cavernous sinus and, through the superior orbital fissure, enters the orbit, branching again to provide sensation of the lacrimal apparatus, cornea, iris, forehead, ethmoid and frontal sinuses and the nose. The ophthalmic nerve –V1- is the smallest of the three divisions, dividing in to three main branches: the nasociliary, frontal and lacrimal nerves (Figure 1).

**The maxillary branch** is **the** second branch of the trigeminal nerve – V2 – passes horizontally forward, through the lateral wall of the cavernous sinus, exiting the cranium through the rotundum foramen which is located in the greater wing of the sphenoid bone. Once outside the cranium, this nerve crosses between the pterygoid plates of the sphenoid bone and the palatine bone. As the maxillary nerve crosses the pterygopalatine fossa, it gives off branches to the posterior–superior alveolar nerve, the sphenopalatine ganglion and the zygomatic region. Branches of this nerve continue through the inferior orbital fissure and infraorbital foramen, providing sensation of the maxillary sinuses, upper jaw, sides of the nose and the cheek (Figure 2). [5, 6]

The branches of the maxillary nerve are given off in four regions:


The branch entering the cranium –the middle meningeal nerve– travels with the middle meningeal artery to provide sensory innervation of the dura mater.

Several branches are given off in the pterygopalatine fossa namely the zygomatic nerve, the pterygopalatine nerve and the posterior superior alveolar nerve.

**The greater palatine nerve** descends through the pterygopalatine canal and through the greater palatine canal emerges on the hard palate, coursing anteriorly between the osseous hard palate and the mucoperiosteum supplying sensory innervation to the bone and palatal soft tissues as far anterior as the first premolar.

syndrome are the most common reactions. Others include tonic-clonic spasm, bronchospasm and angina pectoris. Continual research in the field of pain control is still being done in the

Management of pain in dentistry requires knowledge about the fifth cranial nerve anatomythe trigeminal nerve. It is the largest of the cranial nerves and has three major divisions:

**The trigeminal nerve** is the major sensory nerve of the face containing both motor fibers for masticatory muscles and sensory fibers. This nerve exits the brain through the area between

**The ophthalmic branch** runs through the lateral wall of the cavernous sinus and, through the superior orbital fissure, enters the orbit, branching again to provide sensation of the lacrimal apparatus, cornea, iris, forehead, ethmoid and frontal sinuses and the nose. The ophthalmic nerve –V1- is the smallest of the three divisions, dividing in to three main branches: the

**The maxillary branch** is **the** second branch of the trigeminal nerve – V2 – passes horizontally forward, through the lateral wall of the cavernous sinus, exiting the cranium through the rotundum foramen which is located in the greater wing of the sphenoid bone. Once outside the cranium, this nerve crosses between the pterygoid plates of the sphenoid bone and the palatine bone. As the maxillary nerve crosses the pterygopalatine fossa, it gives off branches to the posterior–superior alveolar nerve, the sphenopalatine ganglion and the zygomatic region. Branches of this nerve continue through the inferior orbital fissure and infraorbital foramen, providing sensation of the maxillary sinuses, upper jaw, sides of the nose and the

The branch entering the cranium –the middle meningeal nerve– travels with the middle

Several branches are given off in the pterygopalatine fossa namely the zygomatic nerve, the

**The greater palatine nerve** descends through the pterygopalatine canal and through the greater palatine canal emerges on the hard palate, coursing anteriorly between the osseous

quest for novel techniques and safer drugs. [1-4].

4 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

ophthalmic, maxillary and mandibular.

the pons and the middle cerebellar peduncles.

nasociliary, frontal and lacrimal nerves (Figure 1).

The branches of the maxillary nerve are given off in four regions:

meningeal artery to provide sensory innervation of the dura mater.

pterygopalatine nerve and the posterior superior alveolar nerve.

**2. Anatomy**

cheek (Figure 2). [5, 6]

**2. Pterygopalatine fossa**

**3. Infraorbital canal**

**1. Cranium**

**4. Face**

**The lesser palatine nerve** travels along with the posterior palatine nerve emerging from the lesser palatine foramen.

**The posterior superior alveolar nerve (PSA)** branches from the main trunk of the maxillary division into the pterygopalatine fossa just before the maxillary division enters the infraorbital canal.

**The maxillary division (V2)** gives off two significant branches namely the anterior superior (ASA) and middle superior (MSA) alveolar nerves.

**The ASA nerve** – given off from the infraorbital nerve – descends within the anterior wall of the maxillary sinus, providing pulpal innervation of the central and lateral incisors, canine and the sensory innervation of periodontal tissues, buccal bone and the mucous membrane of the gums.

**The MSA nerve** provides sensory innervation of maxillary premolars and, perhaps, the mesiobuccal root of the first molar, periodontal tissues, buccal soft tissues and the bone and gums in the premolar region.

**Branches of the face:** through the infraorbital foramen, the infraorbital nerve emerges into the face dividing into its terminal branches: the inferior palpebral, external nasal and superior labial.

**The mandibular branch (V3)** is considered a motor-sensory nerve innervating masticatory muscles, lower jaw and teeth, parotid and sublingual gland, two third of the tongue and the ear canal and exits the skull through the ovale foramen. The mandibular division: The mandibular division – the largest branch of the trigeminal nerve – descends between the medial ramus and the medial pterygoid muscle, entering the mandible through the mandibular foramen (Figure 2.).

**The inferior alveolar nerve** has the largest diameter of 2.4±0.4 mm at the lingula.

**The anterior division of the V3** branch provides sensory innervation of the cheek, mucous membrane in the buccal of the mandibular molars and motor innervation of the masticatory muscles.

**The buccal nerve**, passing through the two heads of the lateral pterygoid, reaches the external surface of the lateral pterygoid muscle, continuing in an anterolateral direction.

**The auriculotemporal nerve** passes through the upper part of the parotid gland crossing the posterior portion of the zygomatic arch.

**The lingual nerve** travels downward and medial to the lateral pterygoid muscle, lying between the ramus and the medial pterygoid muscle in the pterygomandibular space as it descends. The sensory tract of the anterior two-third of the tongue, the mucous membrane of the mouth floor and mandibular lingual gingiva is provided by the lingual nerve.

**Figure 1.** The superficial branches of the trigeminal nerve

**Figure 2.** Branches of the trigeminal nerve

**The mylohyoid nerve** branches off the inferior alveolar nerve just before the entrance of the inferior alveolar nerve into the mandibular canal. This is a mixed nerve providing sensory innervation of the mandibular incisors, and portions of mandibular molars in some. It also provides the motor innervation of the anterior belly of the digastrics and the mylohyoid muscle.

At the mental foramen, the inferior alveolar nerve branches into its terminal branches-- the incisive and the mental nerves:

**The incisive nerve**, remaining within the mandibular canal, forms a nerve plexus innervating the pulpal tissues of the mandibular first premolar, canine and incisors via the dental branches.

**The mental nerve** innervates the skin of the chin and the mucous membrane of the lower lip. [1-6]
