-------------------------------------------------------------------------------- TITLE: Autonomic Nervous System of the Head and Neck SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds DATE: November 30, 1989 RESIDENT PHYSICIAN: Mark L. Nichols, M.D. FACULTY: Charles M. Stiernberg, M.D. SERIES EDITOR: Francis B. Quinn, Jr., M.D. -------------------------------------------------------------------------------- "This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion." HISTORICAL PERSPECTIVE I. GALEN (A.D. 130-200) Distinguished the Sympathetic Trunks Superior and Inferior Cervical Ganglia; Originated the idea that "sympathy" exists between all parts of the body; brain and nerves play essential role. II. EUSTACHIUS (1552) Realized that the Vagi and Costal Nerves (sympathetic trunks) were separate entities. III. WILLIS (1664) Accurately described and illustrated autonomic nerves. IV. WHYTT (1751) Accurately theorized pupillary responses to light, accommodation, and convergence. V. MECKEL (1751) Theorized that ganglia were the sites of division and regrouping of nerve fibers. VI. BARNARD (1858) Found that stimulation of sympathetic fibers to the submandibular gland produced vasoconstriction, stimulation of the Chorda Tympani produced vasodilatation. VII. LUDWIG (1851) Stimulation of the Chorda Tympani increases salivation. VIII. GASKELL (1886) Demonstrated complete structural and functional relationships of the ANS. Noted that some nerves provided inhibit and excitatory functions: described cranial,thoracolumbar and sacral outlets; coined the terms anabolic and catabolic for nerves. IX. LANGLEY (1889) Discovered the paralyzing action of nicotine on cells in the sympathetic ganglia Suggested that craniosacral and thoracolumbar outflows should be classified under the title "Autonomic Nervous System." X. OLIVER and SCHAFER Discovered epinephrine in 1894. XI. LANGLEY (1901) Established the sympathomimetic properties of epinephrine. Discovered the parasympathomimetic effects of pilocarpine. Stated that the term sympathetic should be reserved for the thoracolumbar outflow, parasympathetic for craniosacral outflow. XII. DALE (1913) Important work with Acetylcholine and and pharmacologic approach to the ANS. XIII. MAYO (1931), & Mallory (1935) ANS plays a role in disease. EMBRYOLOGY OF THE AUTONOMIC NERVOUS SYSTEM A. Sympathetic Nervous System 1. By the fifth week of development, cells originating in the neural crest of the thorax, migrate behind the dorsal aorta to form a chain of segmentally arranged sympathetic ganglia interconnected by longitudinal nerve fibers to form the sympathetic chains. 2. Neuroblasts in the thorax migrate craniocaudally to extend the chain into cervical and lumbosacral regions 3. Nerve fibers from the intermediolateral cell column of the spinal cord in the thoracolumbar segment, penetrate the chain ganglia to synapse with the neuroblasts. 4. Some of these nerve fibers from the intermediolateral cell column ascend to higher and lower levels of the sympathetic chain prior to synapsing. B. Parasympathetic Nervous System 1. Parasympathetic ganglia found along side the oculomotor, facial, glossopharyngeal and vagus nerves 2. Origins of the PNS controversial 3. Some feel that cells migrate out of the CNS along preganglionic fibers of cranial nerves III, VII, IX, and X. 4. Other anatomists feel that the PNS arises in sensory ganglia of the cranial nerves 5. The postganglionic fibers of the parasympathetic ganglia pass to the branchial arches and to the cardiac, pulmonary, and intestinal plexuses. III. BASIC AUTONOMIC PHARMACOLOGY A. ADRENERGIC 1. Preganglionic Autonomic: (Sympathetic & Parasympathetic) -Release Acetylcholine (ACh) onto Nicotinic Postganglionic Receptors 2. Post-ganglionic Sympathetic -Release Norepinephrine onto Postganglionic Alpha and Beta Receptors -Exception: Postganglionic Sympathetic fibers to sweat glands release ACH. B. CHOLINERGIC 1. Postganglionic Parasympathetic -Release Ach onto Muscarinic Cholinergic Receptors C. PROTOTYPE AGONISTS AND ANTAGONISTS OF THE ANS 1. Preganglionic Autonomic (PNS,SNS) a. Agonist DMPP dimethylphenyl piperazinium b. Antagonist Hexamethonium C-6, D-Tubocurare 2. Postganglionic Sympathetic a. Alpha receptor 1) Agonist Phenylephrine 2) Antagonist Phenoxybenzamine b. Beta receptor 1) Agonist Isoproterenol 2) Antagonist Propranolol 3. Postganglionic Parasympathetic Muscarinic Receptor a. Agonist Methacholine b. Antagonist Atropine A. GENERAL 1. Preganglionic cell bodies a. Sympathetic Thoracolumbar T1 - L2 b. Parasympathetic Craniosacral 2. ANS is entirely a MOTOR system 3. Responses without conscious control or awareness 4. Autonomic innervation primarily confined to smooth and cardiac muscle, arrector pili muscle, hair follicles, and myoepithelial cells of the glands 5. Postganglionic neurons outnumber preganglionic neurons 32:1 B. SYMPATHETIC 1. Origin: Intermediolateral cell column T1 - L2 spinal cord 2. Myelinated axons: White rami communicantes exit this column via the ventral motor roots T1 - L2 3. After synapsing they exit the sympathetic trunks as gray rami communicantes - unmyelinated 4. There are 3 cervical sympathetic ganglia: superior, middle, and inferior. 5. Preganglionic fibers from white rami of the upper thoracic nerves distributed mainly to the superior cervical ganglion. C. PARASYMPATHETIC NERVOUS SYSTEM 1. Craniosacral origin with CN: III, VII, IX, and X S2, 3, and 4 2. Ganglia lie close to structure of innervation 3. Four ganglia associated with cranial parasympathetic system: a. Ciliary b. Pterygopalatine c. Submandibular d. Otic 4. Vagus (X) has a minimal role in autonomic innervation of the head and neck V. AUTONOMIC NERVOUS SYSTEM OF THE HEAD A. OCULOMOTOR NERVE (CNIII) - CILIARY GANGLION 1. Motor - to all extrinsic extraocular muscles except superior oblique and lateral rectus. 2. Origin - Oculomotor nucleus at the level of superior colliculus. 3. Parasympathetic Origin Edinger-Westphal nucleus rostral and dorsomedial to CN III nucleus 4. Innervation a. Preganglionic Parasympathetic -via CN III. It divides in the cavernous sinus into a superior and inferior ramus. The autonomic fibers pass with the inferior ramus into the orbit and terminate in the ciliary ganglion. b. Postganglionic Parasympathetic -from the ciliary ganglia via the short ciliary nerves to enter the globe to supply the smooth muscle of the ciliary body and the sphincter pupillae of the iris. c. Postganglionic Sympathetic -from the superior cervical ganglion via the internal carotid artery plexus. Fibers pass from the plexus through the ciliary ganglia without synapsing. Sympathetic fibers continue via the short ciliary nerves to the globe to innervate the dilator pupillae muscle . d. Sensory Innervation -via the nasociliary nerve, a branch of the ophthalmic nerve V1. 5. NORMAL PUPILLARY REFLEXES: A. Light: Impulses travel via the optic nerve, optic chiasm, lateral geniculate body to synapse in the pretectal nucleus. From the pretectal nuclei projections extend to ipsilateral and contralateral Edinger-Westphal nuclei to stimulate the constrictor centers. Efferent arc is via preganglionic parasympathetic fibers travelling with CN III to the ciliary ganglion and sphincter pupillae. Actions: direct and consensual pupillary constriction (miosis). B. Accommodation: Cortical voluntary effort via the Edinger- Westphal Nuclei. Efferent arc via CN III to synapse in the Ciliary Ganglion and ultimately innervate the Sphincter Pupillae and Ciliary Body via the Short Ciliary Nerves. Actions: convergence, pupillary constriction, and alteration in lens configuration for near vision. C. Darkness: Afferent loop same as light response. Probable stimulation of an area adjacent to the Edinger-Westphal Nucleus and possibly via the Hypothalamus. Efferent path is via the Sympathetic Nervous System, Superior Cervical Ganglia, Internal Carotid Plexus to the Ciliary Ganglion to distribute postganglionic sympathetic fibers to the Dilator Pupillae. Actions: Darkness causes pupillary dilatation. D. Ciliospinal: Cutaneous afferents from an area sustaining noxious stimuli via a spinal reflex to T1 efferent sympathetic fibers. Efferent loop same as for darkness. Actions: Painful stimuli initiate pupillary dilatation. 6. ABNORMAL PUPILLARY FUNCTION A. Horner's syndrome: Discovered by Claude Bernard (1853) 1. Syndrome consists of pupillary constriction, enophthalmos, ptosis and lack of sweating over the ipsilateral face. 2. Causes: interruption of sympathetic pathways in the medulla, spinal cord, or peripheral sympathetic trunk. Clinically seen in Wallenberg's Syndrome, CVA, Syringomyelia, Trauma. Rare causes include suppurative otitis media, and post tonsillectomy. B. Argyll Robertson Pupil: Discovered by Douglas Argyll Robertson (1869) 1. Diagnosis based on 5 characteristics: a. The Retina is light sensitive b. The Pupil does not contract to light c. The Pupil contracts on accommodation for near vision d. The Pupil contracts with Physostigmine (agonist), but Atropine (antagonist) produces poor dilatation. e. The Pupil must be small 2. Causes: Syphillis a. CN III at the Ciliary Ganglion via arachnoiditis b. Pupillomotor fibers as the enter the Midbrain c. Midbrain lateral to the Aqueduct of Sylvius C. Tonic Pupil: 1. Characteristics: a. common in young females b. unilateral c. mydriasis to direct and consensual stimuli poor d. slow dilatation in prolonged darkness slow constriction in prolonged light e. delay in pupil constriction in accommodation f. Adie's Syndrome: tonic pupil + arreflexia g. discern versus normal pupil 2.5% solution of Methacholine -no effect if normal pupil -strongly constrict if tonic 2. Etiology: (hypothesis) secondary to partial parasympathetic denervation, disturbance in the Ciliary Ganglion. D. The Small Pupil: 1. Etiology: Meningitis, pilocarpine instillation, morphine, histamine 2. Pinpoint Pupils: Pontine hemorrhage or infarct, lesions in the Subthalamus, Thalamus, interruption of ascending Sympathetic pupillodilator fibers E. The Large Pupil: 1. Etiology: Traumatic irridioplegia, unilateral mydriasis via Hippocampal herniation through the Tentorium with compression of CN III as it exits the brainstem. Temporal Arteritis, CVA B. FACIAL NERVE (CN VII) - PTERYGOPALATINE/SUBMANDIBULAR GANGLIA 1. Motor - To muscles of facial expression, platysma, posterior belly of digastric, stylohyoid, stapedius muscles. 2. Origin - Facial nucleus - lateral tegmental area caudal pons. 3. Parasympathetic Origin: general visceral efferent; superior salivatory nucleus. Dorsal to CN VI nucleus. 4. Innervation: - Preganglionic Parasympathetic fibers from the Superior Salivatory Nucleus as well as Taste fibers from the anterior 2/3 of the Tongue join CN. VII after it has curved around the Abducent (CN VI) Nucleus. These fibers exit the brainstem in a separate bundle along with CN VII (Glossopalatine Nerve). The Glossopalatine Nerve enters the Internal Acoustic Meatus between CN VII and VIII. A portion of the Preganglionic Parasympathetic fibers then exit CN VII at the Geniculate Ganglion as The Greater Superficial Petrosal Nerve. The remainder of the Preganglionic Parasympathetic fibers exit Ganglion with CN VII. As the Facial Nerve passes through the vertical portion of its canal, a motor fiber exits to supply the Stapedius muscle, and the remainder of the Preganglionic Parasympathetic fibers exit with taste fibers in the Chorda Tympani. - The Greater Superficial Petrosal Nerve carries preganglionic secretomotor fibers via a small canal in the Petrous portion of the Temporal Bone. The nerve emerges in a hiatus at the anterior surface of the Petrous Temporal Bone and runs in a groove beneath the Dura Mater to the Foramen Lacerum, where it unites with Preganglionic Sympathetic fibers from the Deep Petrosal Nerve via the Internal Carotid Plexus. It continues as the Nerve of the Pterygoid Canal to ultimately terminate in the Sphenopalatine Ganglion. Only Parasympathetic nerves synapse here, Sympathetic and sensory fibers pass uninterrupted. Secretomotor fibers exit the ganglion and enter the Maxillary Nerve V2 where they subsequently course to the Zygomaticotemporal Nerve to the Lacrimal Gland, and via Nasal and Palatine Nerves to the mucous glands and blood vessels of the nasal cavity and palate. - The Chorda Tympani Nerve carrying Preganglionic Parasympathetic fibers as well as taste fibers arises from the Facial Nerve 3-6 mm. above the Stylomastoid Foramen to enter the Aperture of the Posterior Canaliculus for The Chorda Tympani Nerve. It then courses anterosuperiorly to enter the tympanic cavity just posteriorly to the Tympanic Membrane and across the TM to enter the Anterior Canaliculus for the CT which opens anteriorly at the Petrotympanic Fissure where it exits the skull. The CT then joins the posterior border of the Lingual Nerve (V3). The Parasympathetic fibers continue until they synapse in the Submandibular Ganglion suspended just inferior to the Lingual Nerve. Postganglionic Parasympathetic fibers with Postganglionic Sympathetic fibers from the plexus of the External Maxillary / Facial Artery are then distributed to the Submandibular and Sublingual Glands. 5. TOPOGNOSTIC TESTING -LESIONS OF THE FACIAL NERVE a. Not always accurate in discerning site of lesion (incomplete injury) b. Injury at stylomastoid foramen, 1. VII nerve motor paralysis 2. Ipsilateral facial paralysis c. Injury distal to geniculate ganglion 1. Facial paralysis 2. Ipsilateral loss of taste anterior 2/3 of tongue 3. Loss of submandibular and sublingual salivation 4. Hyperacusis d. Injury in meatal and labyrinthine segments 1. Interference with all functions including lacrimation 6. CLINICAL SYNDROMES a. RAMSAY HUNT SYNDROME - HERPES ZOSTER OTICUS: characteristics: 1. Complete facial paralysis 2. Hyperacusis 3. Loss of taste from the anterior 2/3 of the ipsilateral tongue 4. Impaired secretion from the submandibular and sublingual salivary glands 5. Pain and herpetic eruption on: - Tympanic Membrane - External Auditory Canal - Pinna 6. Acyclovir may be beneficial in treatment b. SYNDROME OF CROCODILE TEARS - GUSTATORY LACRIMAL REFLEX characteristics: 1. Unusual consequence of facial paralysis (Bell's Palsy) 2. Ipsilateral tearing occurs when spicy foods are placed on the tongue 3. Etiology: faulty regeneration/rerouting of fibers responsible for salivation with those responsible for lacrimation 4. Frequently reported (6 - 30%) of Bell's Palsy patients 5. Lesion may be in CN VII proximal to the Geniculate Ganglion 6. Treatment: section Greater Superficial Petrosal Nerve c. VAIL'S SYNDROME: 1. Severe attacks of unilateral nocturnal neuralgic pains of the nose, eye, face, neck and shoulder 2. Etiology: Vidian Nerve neuralgia C. GLOSSOPHARYNGEAL NERVE / OTIC GANGLION 1. Motor Origin: Nucleus Ambiguus, motor to the stylopharyngeus muscle. 2. Autonomic Parasympathetic: Preganglionic fibers- Superior Salivatory Nucleus, general visceral efferent 3. Innervation - Preganglionic Parasympathetic fibers exit the brainstem and travel along with CN IX to exit the skull via the Jugular Foramen. As the nerve emerges from the foramen, a recurrent branch of CN IX - Jacobson's Nerve re-enters the skull via the Inferior Tympanic Canaliculus, which opens into the floor of the middle ear. The nerve fibers then enter the mucosa to supply sensory innervation to the Oval and Round Windows, the Eustachian Tube, the Mastoid Air Cell System, and courses anterosuperiorly over the promontory as the Tympanic plexus. The Parasympathetic Fibers then penetrate the roof of the tympanic cavity to enter the subdural space in the Middle Cranial Fossa. The nerve fibers then descend over the Petrous ridge as the Lesser Superficial Petrosal Nerve to exit the skull at Foramen Ovale adjacent to V3 - Mandibular division of CN V. The Preganglionic Parasympathetic fibers then synapse in the Otic Ganglion. Postganglionic fibers exit the Otic Ganglion to join briefly with the Auriculotemporal Nerve (a branch of V3) and then exit to supply secretomotor fibers to the Parotid Gland. Postganglionic Sympathetic fibers via the plexus in the Middle Meningeal Artery pass through the Otic Ganglion and subsequently the auriculotemporal nerve to supply the Parotid Gland, skin and sweat glands of the region. - Sensory innervation: taste and sensation to the posterior 1/3 of the tongue, sensory to the tonsils, fauces, and carotid sinus. 4. CLINICAL SYNDROMES a. AURICULOTEMPORAL SYNDROME - FREY'S SYNDROME (GUSTATORY SWEATING) 1. Ingestion of highly seasoned food in general produces: -flushing -warmness -excessive perspiration over the cheek and pinna 2. Approximately 25% cases following injury to Auriculotemporal nerve 3. Most common causes: Parotidectomy, Parotid abscess 4. Symptoms usually well tolerated (90%) 5. Etiology: regeneration of disrupted secretomotor fibers which become misdirected and innervate sweat glands of the skin and blood vessels 6. Treatment: Auriculotemporal nerve section Tympanic neurectomy VI. AUTONOMIC NERVOUS STRUCTURES IN THE NECK A. VAGUS NERVE (CN X) 1. Largest single contributor to the PNS 2. Motor components extend from the cervical region to descending colon 3. Autonomic component largest preganglionic parasympathetic - origin in dorsal motor nucleus of vagus in medulla 4. Exits jugular foramen descends in the neck posteriorly in the carotid sheath. Gives off motor and sensory branches to visceral structures in the neck. 5. Autonomic innervation limited to the thorax and abdomen B. SYMPATHETIC TRUNK 1. Ascends in the neck posteriorly to the carotid sheath, anterior to the vertebral transverse processes. 2. Extends to the skull base and into the skull as the internal carotid nerve 3. Three main ganglia a. Superior Cervical Ganglia -supplies structures of the head via the carotid plexuses b. Middle Cervical Ganglia -not identifiable in 25% of subjects -supplies visceral branches to the thyroid and parathyroid glands -a cardiac branch -fine branches to the esophagus and trachea -vascular branches via the common carotid, inferior thyroid, vertebral a., jugular veins c. Inferior Cervical Ganglia -fused with T1 and sometimes T2 to form a Stellate Ganglion in 70 - 80% of subjects -located posteriorly to the first portion of the subclavian artery -supplies communicating branches to branches of the Brachial Plexus -visceral branches to the heart, trachea, and the esophagus -vascular branches supplied to vascular structures of the cevicothoracic inlet. -------------------------------------------------------------------------- BIBLIOGRAPHY Appenzeller, Otto ; The Autonomic Nervous System - An Introduction to Clinical and Basic Concepts, Third Edition, Elsevier Biomedical Press, 1982. 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Yagi, N. et al; Crocodile Tears and Thread Test of Lacrimation, Ann Otol. Rhinol. Laryngology, Suppl. 122, Vol. 95, No.1, Pt. 2, PP. 13-16. 1986. --------------------------------END---------------------------------------