FOCUSED REVIEW - SENSORY INNERVATION OF THE HEAD - TOUCH, PAIN, TEMPERATURE AND TASTE

FOCUSED REVIEW - SENSORY INNERVATION OF THE HEAD - TOUCH, PAIN, TEMPERATURE AND TASTE Mini review of topics not clearly remembered Goal - under 30 minutes 'No sinner was ever saved after the first 20 minutes of a sermon' - Mark Twain

REVIEW - SENSORY INNERVATION OF THE HEAD - TOUCH, PAIN, TEMPERATURE TASTE REVIEW CRANIAL NERVES - MANY CRANIAL NERVES ARE MOTOR MOTOR XII - Hypoglossal - muscles of tongue XI - Accessory - motor to sternocleidomastoid, trapezius IV - Trochlear - eye muscle - Superior Oblique VI - Abducens - eye muscle - Lateral Rectus MOTOR AND AUTONOMIC III - Oculomotor - many eye muscles and Lev. Palp. Sup. + Parasympathetics (constrictor pupil, ciliary muscle) OTHER CRANIAL NERVES PROVIDE SPECIAL SENSES I - Olfactory nerve - smell II - Optic nerve - vision VIII - Vestibulo-cochlear nerve - hearing, balance

FOCUS ON GENERAL SENSATION (TOUCH, PAIN, TEMPERATURE) - ALSO TASTE CONTAINED IN CRANIAL NERVES - V (Trigeminal), VII (Facial), IX (Glossopharyngeal), X (Vagus) Components and Structures 1. Dorsal root of spinal nerve - contains afferent (sensory) axons. 2. Dorsal root ganglion - cell bodies of all sensory neurons (somatic and visceral) are located at dorsal root ganglia; look like swellings attached to dorsal root. 3. Ventral root of spinal nerve - contains efferent (motor) axons REVIEW - SENSORY NEURONS IN SPINAL NERVES Dorsal root ganglion Dorsal root ganglion Dorsal root Dorsal root SPINAL NERVE Ventral root Ventral root

SENSORY GANGLIA ARE ATTACHED TO CRANIAL NERVES Cell bodies of sensory neurons in VII (Facial Nerve) in Geniculate Ganglion Cell bodies of sensory neurons in Trigeminal Nerve are in Trigeminal (Semilunar) Ganglion GENICULATE GANGLION - VII TRIGEMINAL SEMI- LUNAR GANGLION V1 V2 V3 VII exit skull at Stylomastoid Foramen VII, VIII leave Internal Auditory Meatus CLINICAL - COMPRESSION OR DAMAGE TO SENSORY GANGLIA CAN PRODUCE PAIN OR SENSORY LOSS

TRIGEMINAL NERVE – PRECISE SENSATION (TOUCH, PAIN, ETC.) TO SKIN OF FACE, FOREHEAD THREE DIVISIONS POSTERIOR SIDE OF HEAD AND ALL OF NECK - CERVICAL SPINAL NERVES - CERVICAL PLEXUS - C2 - C4 DORSAL PRIMARY RAMI ON POSTERIOR SIDE V1 – OPHTHALMIC DIVISION V2 – MAXILLARY DIVISON V3 – MANDIBULAR DIVISION Boundary- Lateral edge of eye Boundary Lateral edge of mouth CLINICAL TEST - PRECISE SENSATION (GSA) - TWO POINT DISCRIMINATION CLINICAL TEST OF V1: SUPRAORBITAL N.

EXCEPTION - SKIN OF OUTER EAR V, VII, IX, X V1 – OPHTHALMIC DIVISION V2 – MAXILLARY DIVISON V3 – MANDIBULAR DIVISION EXCEPTION:SKIN OF OUTER EARALSO1) VII- FACIAL2) IX - GLOSSO- PHARYNGEAL3) X - VAGUS Boundary- Lateral edge of eye Boundary Lateral edge of mouth CLINICAL - BELL'S PALSY (VII) - PARALYSIS OF FACIAL MUSCLES; IN RECOVERY, PATIENTS COMPLAIN OF EARACHES

TRIGEMINAL NERVE ALSO INNERVATES CORNEA OF EYE CORNEAL REFLEX - V TO VII VII - CLOSE EYELID V- TOUCH CORNEA ORBICU- LARIS OCULI M. LONG CILIARY NERVES (V1) - SENSORY TO CORNEA CORNEA - on surface of eye; transparent; irregularities astigmatism - Palpebral part - Close eyelids - Orbital part - Buries eyelids, Ex. sandstorm NOTE: SHORT CILIARY NERVES (III, CILIARY GANGLION) PARASYMPATHETIC ACTIVATED IN PUPILLARY LIGHT REFLEX NOT CORNEAL REFLEX CORNEA HIGHLY SENSITIVE TO TOUCH CLINICAL TEST - CORNEAL REFLEX - TOUCH DETECTED BY V - PRODUCES BILATERAL CLOSING OF EYELIDS (VII)

TRIGEMINAL NERVE – ALSO INNERVATES STRUCTURES INSIDE OF HEAD NASAL CAVITY NOTE: CRANIAL DURA MATER IS ALSO INNERVATED BY V (ex. Nervus Spinosus V3) ORAL CAVITY

TRIGEMINAL (V1, V2) SENSORY TO NASAL CAVITY General Sensation - (GSA) touch, pain, etc. - V1 Anterior Ethmoidal N. - V2 Nasal Branches - V2 Nasopalatine N. OLFACTORY N. PTERYGO- PALATINE GANGLION V2 NASAL BR. V1 ANT. ETHMOIDAL N. CLINICAL - NASAL CAVITY HAS PRECISE SENSATION; PAIN IS INTENSE AND LOCALIZED Other nerves 1.Olfactory N. - SMELL - in Olfactory Area 2. branches of Facial N. (VII) - PARASYMPATHETICS to Mucous Glands of nose - GVE - from Pterygopalatine Ganglion (hitchhike with branches of V2 (Nasal, Nasopalatine N.) V2 - NASOPALATINE N.

TRIGEMINAL INNERVATES PARANASAL AIR SINUSES Air filled extensions of Nasal Cavity: - All Paired - Develop After birth - Lined by mucous membrane - Drain to Nasal Cavity SENSORY FROM BRANCHES OF V1, V2 FRONTAL SINUSES ETHMOID SINUSES PAIN FROM INFECTED SINUSES IS ACUTE, LOCALIZED MAXILLARY SINUSES

PARANASAL AIR SINUSES All usually paired VIEW: FLOOR OF ANT. CRAN. FOSSA WITH BONE REMOVED A. Frontal - separate by septum, variable size C. Ethmoid- also called aircells (Ant., Mid., Post.) B. Sphenoid - in body of Sphenoid bone NOSE Ethmoid - Blocked Sinus Infection Can Spread to Orbit

FACIAL NERVE - VII - MOTOR AND SENSORY STAPEDIUS - DAMAGE -HYPERCOUSIA - sounds seem too loud MOSTLY REMEMBER MOTOR MUSCLES OF FACIAL EXPRESSION BUCCINATOR MUSCLE - forms wall of mouth, damage - difficulty chewing food, drips from mouth FACIAL PARALYSIS - sagging face, loss of naso- labial fold, inability to close eyelid

FACIAL NERVE (VII) - SENSORY INNERVATION TO HEAD SENSORY FIBERS IN FACIAL NERVE - Chorda Tympani - - taste to ant 2/3 of tongue - parasymp.to Submandibular, Sublingual salivary glands - Gleek CHORDA TYMPANI GENICULATE GANGLION - VII CHORDA TYMPANI - arises in middle ear, joinsLingual nerve (from V3) Note: POST. AURICULAR NERVE - precise, touch to outer ear - Ear pain in Bell's palsy DAMAGE - Loss of taste to ant. 2/3 of tongue; decrease salivation LINGUAL NERVE (V3)

HEAD ALSO HAS VISCERAL SENSORY INNERVATION PRECISE SENSATION - SOMATIC GSA - MOSTLY IN V IMPRECISE SENSATION - PHARYNX AND DERIVATIVES - VISCERAL SENSORY GVA - IN 3 CRANIAL NERVES Nasal Cavity NASOPHARYNX - VII Oral Cavity OROPHARYNX - IX LARYNGOPHARYNX - X Note: Authors disagree on innervation of nasopharynx

GLOSSOPHARYNGEAL NERVE (IX) 3. Carotid branches Sensory – Carotid sinus - blood Pressure Carotid Body - CO2 in blood 4. Motor Nerve to Stylopharyngeus 5. Pharyngeal Branches Sensory to oropharynx 6. Tonsillar Branches Sensory to palatine tonsil 7. Lingual branches Sensory (touch) & taste to post. 1/3 of tongue 1. Tympanic br. to MIDDLE EAR Motor Nerve to Stylopharyngeus Tonsillar Lingual Carotid Pharyngeal br

DAMAGE TO GLOSSOPHARYNEAL NERVE GAG REFLEX Carotid Pharyngeal branches IX – GAG REFLEX IN - IX(Pharyngeal Sensory branches) OUT - X - all muscles of Pharynx (except Stylopharyngeus), all muscles of palate (except Tensor Palati) IX –CENTRAL LESIONS – Nucleus solitarius - GVA-- 9,10: cardiac-pulmonary areflexia; loss of chemo-baro-sensory afferents in the carotid sinus/body (Carotid branch IX)

SENSORY INNERVATION OF TONGUE TOUCH - PRECISE TO ANT. 2/3 IMPRECISE TO POST. 1/3 TASTE ANT. TO EPIGLOTTIS - X- VAGUS POST. 1/3 OF TONGUE - IX - GLOSSO- PHARYNGEAL ANT. 2/3 OF TONGUE VII - CHORDA TYMPANI ANT. TO EPIGLOTTIS - X- VAGUS - IMPRECISE POST. 1/3 OF TONGUE IX - GLOSSO- PHARYNGEAL - IMPRECISE ANT. 2/3 OF TONGUE V3 - LINGUAL N. PRECISE TOUCH IMPRECISE PRECISE SENSATION MOTOR - ALL MUSCLES INNERVATED BY XII HYPOGLOSSAL – TONGUE DEVIATES TOWARD SIDE OF HYPOGLOSSAL LESION (GENIOGLOSSUS)

FOCUSED REVIEW - SENSORY INNERVATION OF THE HEAD - TOUCH, PAIN, TEMPERATURE AND TASTE