Anesthesia and Pain Control 1: Anatomical Considerations for Local Anesthesia- Dr. Synan

Olfactory

Sensory

CN I

Optic

Sensory

CN II

Oculomotor

Motor

CN III

Trochlear

Motor

CN IV

Trigeminal

Mixed:

- V1: Sensory

- V2: Sensory

- V3: Sensory, Motor

CN V

Abducens

Motor

CN VI

Facial

Motor

CN VII

Auditory

Sensory

CN VIII

Glossopharyngeal

Mixed

CN IX

Vagus

Mixed

CN X

Accessory

Motor

CN XI

Hypoglossal

Motor

CN XII

Provides sensation of smell

Innervates olfactory mucosa in the roof of the nose

Olfactory:

Provides sensation of vision

Innervates the retina

Optic:

Moves eye up, down, and medially, and raises eyelid; Carries parasympathetics to pupil and ciliary muscle; constricts pupil and accommodates lens

Innervates:

Superior, inferior, and medial rectus muscle, inferior oblique muscles, levator palpebrae superioris muscle

Oculomotor:

Moves eye down and lateral

Innervates superior oblique muscle

Trochlear:

Mixed

V1 = Sensory

V2 = Sensory

V3 = Sensory, motor

Trigeminal

Moves eye laterally

Innervates lateral rectus muscle

Abducens

5 branches:

- Temporal

- Zygomatic

- Buccal

- Marginal Mandibular

- Cervical

Innervates muscles of facial expression

- The chorda tympani branch provides taste sensation to the anterior 2/3 of the tongue. Travels along with the lingual nerve

Facial:

Provides sensation of hearing and equilibrium

Innervates cochlear and semicircular canals of inner ear

Auditory:

Provides taste and sensation to posterior 1/3 of tongue

Carries parasympathetic fibers to parotid gland

Elevates pharynx during swallowing

Innervates stylopharyngeus muscle

Glossopharyngeal:

Provides parasympathetic innervation to influence breathing, heart rate, digestion, etc

Innervates thoracic and abdominal organs, heart, lungs, upper digestive tract

Also innervates skeletal muscle of pharynx and larynx which assists in swallowing

Vagus:

Innervates SCM, trapezius, larynx muscles

The spinal portion of the nerve innervates SCM/Trapezius which influences shoulder and neck movement

The Accessory cranial fibers innervate intrinsic laryngeal muscles of the larynx which controls the vocal cords

Accessory:

Innervates hyoglossus, styloglossus, genioglossus, geniohyoid, and intrinsic muscles of tongue

Hypoglossal:

Smaller than sensory root

Exits cranium through foramen oval with V3, the mandibular division of the sensory root of trigeminal nerve

It then enters the infratemporal fossa

Trigeminal Nerve motor root

1. Masticatory

- masseter

- temporalis

- medial pterygoid

- lateral pterygoid

2. Mylohyoid

3. Anterior belly of digastric

4. Tensor tympani

5. Tensor veli palatine

Trigeminal nerve- motor root innervates the following muscles

Ophthalmic division V1:

- Exits skull via superior orbital fissure into the orbit

Maxillary division V2:

- Exits skull via foramen rotundum into the pterygopalatine fossa

Mandibular division V3:

- Exits skull via Foramen oval into infratemporal fossa along with motor root of the trigeminal nerve

Trigeminal nerve- sensory root

Pure sensory

Smallest division

Divdes into 3 branches

- nasociliary nerve

- frontal nerve

- lacrimal nerve

Supplies eyeball, conjunctiva lacrimal gland, mucous membrane of nose and paranasal sinuses and skin of forehead, eyelids, and nose

Ophthalmic division V1:

Supplies mucous membrane of nasal septum and lateral wall of nasal cavity

Ethmoidal and sphenoid sinuses

Iris, cornea

Skin of lacrimal sac

Skin of nose

Ophthalmic Division V1- Nasociliary Nerve Branch

Largest branch of ophthalmic division

Divides into supratrochlear and supraorbital N.

Supplies conjunctiva and skin of upper eyelid, skin of forehead, anterior scalp and mucus membrane of frontal sinus

Ophthalmic Division V1- Frontal nerve branch

Smallest branch of ophthalmic division

Supplies skin and conjunctiva of lateral aspect of upper eyelid, forehead, and lacrimal gland

Ophthalmic Division V1- Lacrimal Nerve Branch

Pure sensory

Intermediate in size

Supplies:

1. Dura mater within cranium

2. Skin of

- Middle portion of face

- Lateral forehead

- Cheek bone

- Lower eyelid

- Side of nose

- Upper lip

3. Mucous membrane

- Nasopharynx

- Maxillary sinus

- Soft palate

- Tonsil

- Hard palate

4. Maxillary teeth and periodontium

Maxillary division of V2

Branches within the cranium

- middle meningeal nerve

Branches within the pterygopalatine fossa

- zygomatic nerve

-- zygomaticotemporal nerve

-- zygomaticofacial nerve

- Pterygopalatine nerve

-- Orbital brancehs

-- Nasal branches

---- Nasopalatine nerve

---- PSLN

---- PILN

-- Palatine branches

-- Greater (anterior) palatine nerve

-- Lesser (middle and posterior) palatine nerves

-- Pharyngeal branch

- Posterior superior alveolar nerve

Maxillary division of (V2) Branches

Zygomaticotemporal N.

- Innervates skin of lateral forehead

Zygomaticofacial N.

- Innervates skin over cheekbone

Maxillary division of V2- Zygomatic Nerve

Orbital branch

- Innervates periosteum of orbit

Nasal branches

- Nasopalatine nerve: innervates anterior septum, floor of nose, anterior 1/3 of hard palate

- Posterior superior lateral nasal

- Posteror inferior lateral nasal

Palatine branches

- Greater palatine N: innervates posterior 2/3 of hard palate

- Lesser palatine N: innervates soft palate and tonsil

Pterygopalatine nerves

- Pharyngeal branch: innervates nasopharynx

Maxillary division of V2- Pterygopalatine nerves

Innervates

1. Mucous membrane of posterior maxillary sinus

2. Buccal gingiva of maxillary molars

3. Periodontium and pulp of maxillary molars except mesiobuccal root of 1st molar in 28% of cases

Maxillary division of V2- Posterior superior alveolar nerve

a. middle superior alveolar nerve

b. anterior superior alveolar nerve

Maxillary division of V2- Branches within the infraorbital canal

Present in about 46-72% of patients

Provides pulpal and periodontium innervation to the maxillary premolars and perhaps the mesiobuccal root of the maxillary 1st molar. Also innervates the buccal gingiva in the premolar area

Middle superior alveolar nerve

Provides pulpal, periodontium, and labial gingival innervation to the maxillary central incisor, lateral incisor, and canine

note:

- MSA nerve is NOT present the ASA nerve also typically innervates the premolars

Anterior superior alveolar nerve

a. Inferior palpebral branches

- Innervates skin of lower eyelids

b. external nasal branches

- Innervates skin of lateral aspect of nose

c. superior labial branches

- Innervates skin and mucous membrane of upper lip

Maxillary division of V2- Branches of the face

Nasal branches

- nasopalatine nerve

Palatine branches

- greater palatine nerve

- Lesser palatine nerves

Posterior Superior Alveolar nerve

Branches of Maxillary Division with Special Significance in Dentistry: Pterygopalatine nerves

Middle superior alveolar N

Anterior superior alveolar N

Branches of Maxillary Division with Special Significance in Dentistry: Infraorbital canal

Incisive papilla

Greater palatine foramen- nerve innervates posterior 2/3 of hard palate

Nasopalatine foramen- nerve innervates anterior 1/3 of hard palate

Lesser palatine foramen- nerve innervates soft palate and tonsils

Palatine nerves

Mixed nerve

Largest division of trigeminal nerve

Branches in thee areas:

- Branches from the undivided nerve

- Branches from anterior division

- Branches from the posterior division

Mandibular Division of V3

Skin of:

- Temporal region

- Auricular region

- External auditory meatus

- Cheek

- Lower lip

- Chin

Mucous membrane of:

- Cheek

- Tongue (anterior 2/3rds)

- Mastoid cells

Mandibular teeth and periodontium

Bone and mandible

Temporomandibular joint

Parotid gland

Mandibular Division of V3: Sensory innervation

Masticatory muscles

Mylohyoid

Anterior belly of digastric

Tensor tympani

Tensor veli palatini

Mandibular Division of V3: Motor innervation

Nervus spinosus:

- Dura mater

- Mastoid air cells

Nerve to medial pterygoid muscle

- Small br. to tensor veli palatini

- tensor tympani

Mandibular Division of V3: Undivided nerve

Nerve to lateral pterygoid muscle

Nerve to masseter muscle

Nerve to temporalis muscle

Buccal Nerve (buccinator nerve or long buccal nerve)

Mandibular Division of V3: Divided nerve (anterior division)

sensory

Buccal nerve provides ______ innervation to skin of cheek, and mucous membrane of cheek and buccal gingiva of mandibular molars

buccinator muscle, facial nerve innervates buccinator muscle

Buccal nerve does not innervate the

Auriculotemporal nerve

Lingual nerve

Mylohyoid nerve

Inferior alveolar nerve: dental br

Incisive branch: dental branches

Mental nerve

Mandibular Division of V3: Divided nerve (posterior division)

Skin over zygomatic area, cheek, and mandible

Parotid gland

Skin of external auditory meatus and tympanic membrane

Posterior portion of temporomandibular joint

Skin over temporal region

Auriculotemporal nerve-innervates

Pure sensory

Runs anterior and medial to inferior alveolar nerve. Located at the side of the base of the tongue just below and behind mandibular 3rd molar

innervates

- anterior two-thirds of tongue (general sensation)

- Mucous membrane of floor of mouth

- Lingual gingiva of mandible

NOTE:

- Chorda tympani (a branch of the facial nerve) provides senastion of taste to anterior two-thirds of tongue

Lingual nerve

Mixed nerve

Branches from inferior alveolar Nerve before IAN enters mandibular canal

Runs downward and forward in mylohyoid groove on medial surface of mandible

Innervates

- mylohyoid muscle (motor)

- Anterior belly digastric (motor)

- Skin of mental protuberance (sensory)

- Sensory innervation of mandibular incisors

- Sensory innervation to mandibular molars

Mylohyoid nerve

Supplies pulpal innervation to mandibular molars and second premolars and sensory innervation to buccal periodontium of these same teeth

IAN

Supplies pulpal innervation and sensory innervation to buccal periodontium of mandibular 1st premolar, canine, and incisors

Incisive nerve

Mandibular foramen- target area for inferior alveolar nerve block

Deposition of local anesthetic just superior to mandibualr foramen

Exits inferior alveolar canal through the mental foramen

Divides into three branches that innervate the skin of chin and lower lip and mucous membrane of lower lip and labial gingiva of mandibular premolars and anterior teeth

Mental nerve

- Root eminences

- Canine eminence

- Canine fossa

- Infraorbital foramen

- Pyriform rim

- Anterior nasal spine

- Nasal septum

- Nasal bones

- Zygoma

Important bony landmark in maxilla (anterior surface)

- Pterygomaxillary fissure and fossa

- Foramina for posterior superior alveolar nerve

- Maxillary tuberosity

- Lateral pterygoid plate

- Medial pterygoid plate

Important bony landmark in maxilla (Inferior Temporal surface)

- Palatal processes of maxilla (anterior 3/4ths of hard palate)

- Alveolar process

- Greater (anterior) palatine foramen

- Greater palatine groove

- Incisive foramen (descending palatine artery nasopalatine nerve)

- Premaxilla

- Horizontal process of palatine boen (posterior fourth of hard palate)

- Lesser palatine foramen

- Posterior nasal spine

Important bony landmark in maxilla (palatal surface)

- Condylar head

- Condylar neck

- Coronoid process

- Coronoid notch

- Ramus

- Body of mandible (thick, dense bone)

- Mental foramen

- Alveolar process (less dense bone in anterior)

- Mental protuberance

Important bony landmark in Mandible (Anterior view)

- Condylar head

- Condylar neck

- Sigmoid notch

- Coronoid process

- Coronoid notch (concavity of anterior ramus)

- Ramus

- Body of mandible

- External oblique line

- Mental foramen

- Mental protuberance

- Antegonial notch

- Antelingula

Important bony landmark in Mandible (Lateral View)

- Condylar head

- Condylar neck

- Coronoid process

- Mandibular foramen

- Lingula

- Mylohyoid line

- Lingual foramina

- Genial tubercles

Important bony landmark in Mandible (Lingual view)

halfway between superior and inferior borders and 65%-75% of the distance from the anterior border of the ramus to its posterior border

May range from 1 to 19 mm or more above the level of the occlusal plane

The mandibular foramen is usually located

20-25mm

The thickness of soft tissue between needle penetration and bone of the ramus at the level of the mandibular foramen averages about