FOCUSED REVIEW SENSORY INNERVATION OF THE HEAD TOUCH

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 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) REVIEW - SENSORY NEURONS IN SPINAL NERVES Dorsal root ganglion Dorsal root Ventral root SPINAL NERVE 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

SENSORY GANGLIA ARE ATTACHED TO CRANIAL NERVES Cell bodies of sensory neurons in Trigeminal Nerve are in Trigeminal (Semilunar) Ganglion TRIGEMINAL SEMILUNAR GANGLION VII, VIII leave Internal Auditory Meatus V 2 Cell bodies of sensory neurons in VII (Facial Nerve) in Geniculate Ganglion GENICULATE GANGLION - VII V 1 V 3 VII exit skull at Stylomastoid Foramen 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 V 1 – OPHTHALMIC DIVISION Boundary. Lateral edge of eye V 2 – MAXILLARY DIVISON Boundary Lateral edge of mouth POSTERIOR SIDE OF HEAD AND ALL OF NECK CERVICAL SPINAL NERVES CERVICAL PLEXUS C 2 - C 4 DORSAL PRIMARY RAMI ON POSTERIOR SIDE V 3 – MANDIBULAR DIVISION CLINICAL TEST - PRECISE SENSATION (GSA) - TWO POINT DISCRIMINATION CLINICAL TEST OF V 1: SUPRAORBITAL N.

EXCEPTION - SKIN OF OUTER EAR V, VII, IX, X V 1 – OPHTHALMIC DIVISION Boundary. Lateral edge of eye V 2 – MAXILLARY DIVISON Boundary Lateral edge of mouth V 3 – MANDIBULAR DIVISION EXCEPTION: SKIN OF OUTER EAR ALSO 1) VII- FACIAL 2) IX GLOSSOPHARYNGEAL 3) X - VAGUS 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 CORNEA - on surface of eye; transparent; irregularities astigmatism CORNEA HIGHLY SENSITIVE TO TOUCH VII - CLOSE EYELID V- TOUCH CORNEA LONG CILIARY NERVES (V 1) - SENSORY TO CORNEA NOTE: SHORT CILIARY NERVES (III, CILIARY GANGLION) PARASYMPATHETIC ACTIVATED IN PUPILLARY LIGHT REFLEX NOT CORNEAL REFLEX ORBICULARIS OCULI M. - Palpebral part - Close eyelids - Orbital part - Buries eyelids, Ex. sandstorm CLINICAL TEST - CORNEAL REFLEX TOUCH DETECTED BY V - PRODUCES BILATERAL CLOSING OF EYELIDS (VII)

TRIGEMINAL NERVE – ALSO INNERVATES STRUCTURES INSIDE OF HEAD NASAL CAVITY ORAL CAVITY NOTE: CRANIAL DURA MATER IS ALSO INNERVATED BY V (ex. Nervus Spinosus V 3)

TRIGEMINAL (V 1, V 2) SENSORY TO NASAL CAVITY OLFACTORY N. General Sensation (GSA) touch, pain, etc. - V 1 Anterior Ethmoidal N. - V 2 Nasal Branches - V 2 Nasopalatine N. V 2 V 1 PTERYGOPALATINE GANGLION NASAL BR. 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 V 2 (Nasal, Nasopalatine N. ) V 2 - NASOPALATINE N.

TRIGEMINAL INNERVATES PARANASAL AIR SINUSES SENSORY FROM BRANCHES OF V 1, V 2 FRONTAL SINUSES ETHMOID SINUSES MAXILLARY SINUSES Air filled extensions of Nasal Cavity: - All Paired - Develop After birth - Lined by mucous membrane - Drain to Nasal Cavity PAIN FROM INFECTED SINUSES IS ACUTE, LOCALIZED

PARANASAL AIR SINUSES All usually paired VIEW: FLOOR OF ANT. CRAN. FOSSA WITH BONE REMOVED NOSE A. Frontal separate by septum, variable size C. Ethmoid- also called air cells (Ant. , Mid. , Post. ) B. Sphenoid - in body of Sphenoid bone 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 FACIAL PARALYSIS sagging face, loss of nasolabial fold, inability to close eyelid BUCCINATOR MUSCLE - forms wall of mouth, damage difficulty chewing food, drips from mouth

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 arises in middle ear, joins Lingual nerve (from V 3) DAMAGE - Loss of taste to ant. 2/3 of tongue; decrease salivation GENICULATE GANGLION - VII LINGUAL NERVE (V 3) Note: POST. AURICULAR NERVE precise, touch to outer ear Ear pain in Bell's palsy

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

GLOSSOPHARYNGEAL NERVE (IX) 1. Tympanic br. to MIDDLE EAR Motor Nerve to Stylopharyngeus Tonsillar Lingual 3. Carotid branches Sensory – Carotid sinus - blood Pressure Carotid Body - CO 2 in blood 4. Motor Nerve to Stylopharyngeus 5. Pharyngeal Branches Sensory to oropharynx 6. Tonsillar Branches Sensory to palatine tonsil Carotid 7. Lingual branches Sensory (touch) & taste to post. 1/3 of tongue 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 chemobaro-sensory afferents in the carotid sinus/body (Carotid branch IX)

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