LOCAL ANESTHESIA FOR THE DENTAL HYGIENIST:

Anatomy Review

Main Structures Involved:Facial Bones of the Skull:

-Maxilla, Mandible, and Palatine bones

Cranial Nerve V—Trigeminal nerve:V2-Maxillary branch of the Trigeminal

nerveV3-Mandibular branch of the

Trigeminal nerve

Cranial NervesEmerge from the

inferior surface of the brain

All pass through the foramina (window like opening) of the skull to innervate structures in the head, neck, and facial region

Cranial Nerves (12 pairs)I- OlfactoryII- OpticIII- OculomotorIV- Trochlear

V- Trigeminal VI- AbducentVII- FacialVIII-VestibulocochlearIX- Glossopharyngeal X- VagusXI- Accessory XII- Hypoglossal

Trigeminal Nerve - V

Trigeminal NerveLargest cranial nerve/Most Important

Short trunk from brain with 2 roots

Afferent /Sensory Root [larger]

Has trigeminal ganglionOpthalmic V1Maxillary V2Mandibular V3

Motor /Efferent root [smaller]Muscles of masticationParasympathetic to

salivary glands

Cranial Nerve V (Trigeminal)3

Divisions/branches

• V1 entirely afferent

• V2 entirely afferent

• V3 mixed, both afferent and efferent

Foramen of the Trigeminal Nerve

V-1 Ophthalmic DivisionEnters the eye through the Superior orbital fissure

Sensation to conjuctiva, cornea, eyeball, orbit, forehead, ethmoid sinus, frontal sinus, dura mater of brain

V-2 Maxillary DivisionEnters the skull through

the Foramen Rotundum

Afferent (Sensory) nerve for:

Maxilla and overlying skin and dental plexus

Maxillary sinuses Nasal cavity Palate Nasopharynx Part of dura mater

V2 Branches:Infraorbital Nerve

Sensation for upper lip, medial cheek, lower eyelid and side of the nose

Passes through infraorbital sulcus (groove in floor of orbit) becomes:

Infraorbital canal which terminates at:

Infraorbital foramen

Sensation for Maxillary centrals, laterals, canines, and associated tissues

Originates in pulp tissues of teeth at apical foramen

Joins the infraorbital nerve along anterior wall of maxillary sinus

May cross over midline.

V2 Branches:Anterior Superior Alveolar (ASA)

V2 Branches:Middle Superior Alveolar (MSA)

Sensation for Maxillary premolars and mesiobuccal root of the 1st molar, and buccal gingiva.

Originates in pulp tissues of teeth at apical foramen

Joins the infraorbital nerve along lateral wall of maxillary sinus

Not present on all patients.

Communicates with ASA and PSA nerves.

V2 Branches:Posterior Superior Alveolar (PSA)

Sensation for Maxillary 1st (except MB root), 2nd, 3rd molars, buccal gingiva, and maxillary sinus.

Originates in pulp tissues of teeth at apical foramen

Joins the infraorbital nerve along lateral wall of maxillary sinus

Communicates with ASA and MSA nerves.

V2 Branches: Greater Palatine Nerve

Posterior hard palate and posterior lingual gingivaEnters Greater palatine foramen near 2-3rd molar

V2 Branches: Lesser Palatine NerveSoft Palate and palatine tonsillar tissuesEnters lesser palatine foramen near pterygoid

process

V2 Branches: Nasopalatine Nerve

Mucosa of anterior hard palate and lingual gingiva of maxillary teeth

Enters incisive foramen beneath incisive papillaTravels along nasal septumCommunicates with GP nerve lingual to the maxillary

canines

V-3 Mandibular DivisionEnters the skull through the

Foramen Ovale in Sphenoid boneLargest of three divisionsSensory root to:

CheekExternal ear and scalpTongueSubmand/Sublingual salivary

glandsFloor of the mouthMandibular dental plexus

Motor root to:Muscles of MasticationPalatal muscles

V3 Branches: Buccal NerveSkin of cheekBuccal mucosaBuccal gingiva of

mandibular posterior teeth

Located on surface of buccinator muscle

V3 Branches: Lingual Nerve

Lateral surface of the tongue

Slightly medial to Inferior alveolar nerve

Sensory for body of the tongue, floor of the mouth, and lingual gingiva of mandibular teeth

V3 Branches: Mental Nerve Sensory for chin, lower

lip, and labial mucosa of mandibular pre-molars, and anterior teeth

Merges with the incisive nerve to form the IA nerve

Enters the mental foramen on the anterior surface of the mandible near 1st and 2nd premolar apices

V3 Branches: Incisive Nerve

Sensory for mandibular premolars and anterior teeth pulp tissue

Merges with the mental nerve to form the IA nerve

May crossover midlineEnters the mental

foramen on the anterior surface of the mandible near 1st and 2nd premolar apices

V3 Branches: Inferior Alveolar Nerve Sensory for mandibular

teethFormed from merger of

the mental and incisive nerves

Exits the mandibular foramen on the lingual surface of the ramus

V3 Branches: Mylohyoid Nerve

Efferent (motor) for mylohyoid muscle and anterior belly of digastric muscle

May serve as a afferent nerve for mandibular 1st molar if IA nerve block failure