Cranial nerves Assoc prof Stefan Sivkov MD Ph

Cranial nerves Assoc. prof. Stefan Sivkov, MD, Ph. D

Names I N. olfactorius II N. opticus III N. oculomotorius IV N. trochlearis V N. trigeminus VI N. abducens VII N. facialis VIII N. vestibulocochlearis IX N. glossopharyngeus X N. vagus XI N. accessorius XII N. hypoglossus

Nuclei, components, course

Cranial nerves n Somatic n Somatomotor Somatosensory n General somatosensory n Specific somatosensory Autonomic n Visceromotor n General visceromotor n Specific visceromotor n Viscerosensory n General viscerosensory n Specific viscerosensory n n

Components n n n n General somatosensory fibers (GSS): extero- and proprioseptive impulses from head and face Specific somatosensory fibers (SSS): specific impulses from eye and ear General viscerosensory fibers (GVS): from visceral organs to viscerosensory nuclei. Specific viscerosensory fibers(SVS): specific impulses for smell and taste General somatomotor fibers (GSM): for skeletal muscles of eye and tongue Specific visceromotor fibers (SVM): for skeletal muscles with branchiogenic origin. Mastication, expression, swallowing General visceromotor fibers (GVM): from visceromotor nuclei; relay in parasympathetic ganglia. Heart muscle，smooth muscles, glands.

Nuclei Columns n Medial. Somatomotor. In the central grey matter; derive from basal plate of neural tube; supply striated muscles with myotomic origin; (ІІІ, ІV, VІ, ХІІ). n Ventrolateral. Specific visceromotor. Migrate ventrolaterally forming inner genu; derive from basal plate; supply muscles with branchiogenic origin; (V, VІІ).

n n Visceromotor column. Lateral to medial and dorsal to ventrolateral clmn; derive from basal plate next to sulcus limitans; origin to efferent preganglionic fibers; parasympathetic supply of smooth muscles; (ІІІ, VІІ, ІХ, Х). Sensory column. Lateral to sulcus limitans; derive from alar plate; accept central processes of sensory ganlia cells; n n n General viscerosensory – close to sulcus limitans (VІІ, ІХ, Х). General somatosensory - intermediate, general sensation from head/face (V) Specific somatosensory - lateral, hearing and balance impulses (VІІІ)

Organization of brain stem (after Herrick)

Appearance of brain surface

Course within skull

Exit of skull

Motor, sensory, mixed

Classification n Sensory: only afferent (sensory) fibers q q q n Motor: only efferent (motor) fibers q q q n N. Olfactorius N. Opticus N. Vestibulocochlearis N. N. N. Oculomotorius Trochlearis Abducens Accessorius Hypoglossus N. N. Trigeminalis Facialis Glossopharyngeus Vagus Mixed: sensory and motor fibers q q

Сетивни нерви N. Първи неврон и Вход вид на влакната І Обонятелен епител (СВС) Foramina Bulbus cribrifom olfactorius is Обоняни е ІІ Ганглийни клетки в ретината (ССС) Canalis opticus Зрение VІІІ Ganglion vestibulare (ССС) Meatus acusticus internus Canalis Ganglion cochleare (ССС) spiralis Терминалн Модално и ядра ст Nucleus geniculatu m lateralis Nuclei Баланс vestibulare s Nuclei cochleares Слух

N. olfactorius Обонятелна лигавица (СВС)→ For. cribriformes → Bulbus olfactorius

N. opticus Ganglion cell → Canalis opticus → Corpus geniculatum laterale

N. vestibulocochlearis Ganglion Vestibulare (SSA) - Meatus internus acusticus - Nuclei Vestibulares Ganglion Cochlearе (SSA) - Canalis spiralis - Nuclei Cochleares

Моторни нерви N. Origin Exit Supply ІІІ Nucleus n. oculomotorii (ОСМ) Fissura orbitalis superior Mm. recti superior, inferior, medialis; inferior obliquus; levator palpebrae superioris Nucleus accessorius n. oculomotorii (ОВМ) M. sphincter pupillae и m. ciliaris ІV Nucleus n. trochlearis (ОСМ) Fissura orbitalis superior M. obliquus superior VІ Nucleus n. abducentis (ОСМ) Fissura orbitalis superior M. rectus lateralis XI Nucleus n. accessorii (СВМ) Foramen jugulare M. sternocleidomastoideus и m. trapezius XI I Nucleus n. hypoglossi (ОВМ) Canalis hypoglossi Mускули на езика

N. oculomotorius n Компоненти q q n Ядра q q n Fissura orbitalis superior Инервация q q n латерална стена на sinus cavernosus Напускане на черепа q n sulcus cruris medialis Ход q n nucl. oculomotorius nucl. accessorius Поява q n Общо соматомоторни влакна Общо висцеромоторни влакна Mm. recti superior, inferior, medialis; m. obliquus inferior; m. levator palpebrae superioris M. sphincter pupillae & m. ciliaris Ganglion ciliare : между n. opticus & m. rectus lateralis

Парасимпатикови влакна от nucleus accessorius n. oculomotorii достигат ganglion ciliare по n. oculomotorius (radix parasympathica) и се прекъсват в него. Сетивни влакна от n. nasociliaris (radix sensoria) и симпатикови влакна от plexus caroticus internus (radix sympathica) преминават през ганглия без да се прекъсват. Парасимпатикови влакна достигат (по nervi ciliares breves) до m. cliliaris (акомодация) и m. sphincter pupillae (свиване на зеницата). 2020/12/1 Ganglion ciliare

Damage of n. oculomotorius Diverging strabismus (squinting) n Double vision n Dilated pupil (mydriasis) n Impaired accomodation n

N. trochlearis [IV] Nucleus q Nucl. n. trochlearis (ОСМ) Appearance q Below colliculus inferior Course q Lateral wall of sinus cavernosus q Fissura orbitalis superior Exit Supply q Somatomotorа: n M. obliquus superior

N. abducens [VI] Nucleus Appearance Course Exit Supply Somatomotor: Nucl. n. abducentis (ОСМ) Fissura pontomedullaris, Thru sinus cavernosus, lateral to а. carotis int. Fissura orbitalis superior M. rectus lateralis N. abducens 2020/12/1

Converging strabismus (squinting) n Double vision n Damage of n. abducens

N. accessorius Nucleus Nucl. ambiguus - caudal (SVM) Nucl. spinalis n. accessorii (GSM) Appearance Sulcus retroolivaris – radix cranialis Btw radices ventralis & dorsalis – radix spinalis Course Radix spinalis enters skull thru for. magnum, joins radix cranialis Exit For. Jugulare - pars cranialis – r. externus in n. vagus - pars spinalis – r. externus Supply M. trapezius, m. sternocleidomastoideus

N. hypoglossus [XII] Nucleus Nucl. n. hypoglossi(GSM) Appearance Sulcus anterolateralis btw oliva & pyramis Cisterna basalis Canalis n. hypoglossi Course Exit Supply Somatomotor: Mm. styloglossus, hyoglossus, genioglossus, own muscles of toungue

N. hypoglossus

Mixed nerves

N. trigeminus [V] Components n n SVM: from nucleus motorius n. trigemini, muscles of mastication. GSS влакна: from head and face to sensory nuclei of n. trigeminus; neurons in ganglion trigeminale, lying on pars petrosa на os temporale.

Branches n N. ophthalmicus (V 1, sensory) exits thru fissura orbitalis superior, enters orbit n Branches q N. frontalis: n n q q N. supratrochlearis N. supraorbitalis N. lacrimalis N. nasociliaris

Supply: Sensory: n n Dura mater cerebri Eye Nasal mucosa Skin epicranial & eye area, back of nose Sympathetic fibers for m. dilator pupillae. From upper Th segments, thru superior cervical ganglion. Reach branches of a. carotis interna

N. maxillaris (V 2, sensory) n Exit thru foramen rotundum n Branches q q N. N. infraorbitalis zygomaticus alveolaris superior pterygopalatinus

Supply: n n Dura mater cerebri Teeth – upper jaw Nasal& oral mucosa Skin btwn eyes and mouth

N. mandibularis (V 3, mixed) n Exit thru foramen ovale и enters fossa infratemporalis n Branches q q q N. auriculotemporalis N. buccalis N. lingual N. alveolaris inferior Nn. for masticatory muscles

Supply: Sensory: Dura mater cerebri q Teeth and gums of lower jaw q Mucosa and floor of mouth q Anterior 2/3 of tongue q Skin temporal area, ear, below mouth q Motor: Muscles of mastication, m. mylohyoideus, venter anterior m. digastricus

Facial Nerve VII n n Somatic Motor - facial expressions Autonomic Motor - salivary and lacrimal glands, mucous membranes of nasal and palatine mucosa Special Sensory - taste on anterior 2/3’s of tongue Damage produces sagging facial muscles and disturbed sense of taste (no sweet and salty)

Branches of Facial Nerve Clinical test: Test anterior 2/3’s of tongue with substances such as sugar, salt, vinegar, and quinine; test response of tear glands to ammonia fumes; test motor functions by asking subject to close eyes, smile, whistle, frown, raise eyebrows, etc.

N. facialis [VII] Components n n SVM from nucleus n. facialis for muscles of expression GVM (n. intermedius) from nucleus salivatorius superior, interrupt in ganglion pterygopalatinum & ganglion submandibulare. Postganglionic fibers reach glandulae lacrimalis, submandibularis & sublingualis SVS (n. intermedius) from taste buds in anterior 2/3 of tongue, neurons in ganglion geniculi of n. facialis reaching nucleus tractus solitarii GSS skin external ear

Course Thru meatus acusticus internus, canalis facialis и for. stylomastoideum, enters gl. рarotidea, forming plexus intraparotideus and giving off five branches for muscles of expression

Branches in canalis n. facialis n Chorda tympani: joins n. lingualis of n. mandibularis q q Tate in anterior 2/3 of tongue Interrupt in ganglion submandibulare, postganglionic fibers reaching gl. submandibularis и gl. sublingualis

n n N. petrosus major: GVM fibers to ganglion pterygopalatinum, postganglionic fibers thru n. zygomaticus & n. lacrimalis reach gl. lacrimalis N. stapedius: for m. stapedius

Branches ouside the skull n n n Rr. temporales Rr. zygomatici Rr. buccales R. marginalis mandibulae R. coli

n n Ganglion pterygopalatinum: in fossa pterygopalatine below n. maxillaris Ganglion submandibulare: btw n. lingualis & gl. submandibularis

Damage of n. facialis

Glossopharyngeal Nerve IX n n n Somatic motor – Swallowing and voice production via pharyngeal muscles Autonomic motor - salivation, gagging, control of BP and respiration Sensations from posterior 1/3 of tongue including taste Sensations from baroreceptors and chemoreceptors Damage results in loss of bitter and sour taste and impaired swallowing, blood pressure anomalies (with CN X).

N. glossopharyngeus [IX] Components n n SVM: from nucleus ambiguus to m. stylopharygeus GVM: preganglionic from nucleus salivatorius inferior to ganglion oticum, postganglionic to glandula parotidea SVS: from ganglion inferior, central processes to nucleus tractus solitarii, peripheral processes to posterior 1/3 of tongue GVS: from mucosa of posterior 1/3 of tongue, pharynx, palatine tonsils, tuba auditiva & cavitas tympanica, sinus & glomus caroticus, reach nucleus tractus solitarii

Course: exit thru foramen jugularе Branches n n n Rami linguales: taste buds and mucosa of posterior 1/3 of tongue Rami pharyngei: plexus pharyngeus, sensory and parasympathetic fibers N. tympanicus: GVM thru n. tympanicus & n. petrosus minor reach ganglion oticum, postganglionic thru n. auriculotemporais (Ⅴ 3) for glandula parotidea n Ramus sinus caroticus: for sinus & glomus caroticus n Rami tonsillares & ramus m. stylophayngei Ganglion oticum : below foramen ovale

Vagus Nerve X n n n Sensations from skin at back of ear, external acoustic meatus, part of tympanic membrane, larynx, trachea, espophagus, thoracic and abdominal viscera Sensations from bararoceptors and chemoreceptors Special sensory – taste from epiglottis and pharynx Somatic motor – Swallowing and voice production via pharyngeal muscles Autonomic motor – smooth muscle of abdominal viscera, visceral glands secretions, relaxation of airways, and normal or decreased heart rate. Damage causes hoarseness or loss of voice, impaired swallowing, GI dysfunction, blood pressure anomalies (with CN IX), fatal if both are cut

N. vagus [X] Components n n GVM: nucleus dorsalis n. vagi, interrupt in parasympathetic ganglion, short postganglionic fibers supply heart muscle, smooth muscles and glands SVM: nucleus ambiguus, for muscles of pharynx и larynx GVS: from organs in neck, thorax, abdomen to nucleus tractus solitarii GSS: auricle, meatus acousticus externus & dura mater cerebri

Course n n Exits thru foramen jugulare Descends in vagina carotica btw internal a. carotis interna (communis) & v. jugularis interna N. vagus dexter n n Enters thorax to the right of trachea Descends behind v. brachiocephalica dextra & v. cava superior n Passes behind the root of right lung n Forms plexus esophageus posterior n Forms truncus vagalis posterior in hiatus esophageus, enters abdomen and gives off rami gastrici posteriores celiaci

N. vagus sinister n n Enters thorax btw a. carotis communis & a. subclavia sinistra, behind v. brachiocephalicа sinistra Passes anterior to arch of aorta, giving off n. laryngeus recurrens n Passes behind the root og lefht lung n Forms plexus esophageus anterior n Forms truncus vagalis anterior inв hiatus esophageus, enters abdomen, gives off rr. gastrici anteriores & rr. hepatici

Branches in neck n N. laryngeus superior: descens along pharynx and gives off q q n n Ramus internus, pierces membrana thyrohyoidea and supplies mucosa of larynx to rima glottis Ramus externus, supplies m. cricothyroideus Rami cardiaci cervicales superiores: descend to plexus cardiacus Ramus meningeus, ramus auricularis, rami pharyngei (plexus pharyngeus)

N. laryngeus superior Ramus internus Ramus externus

Thoracic branches n N. laryngeus recurrens q q n Right around а. subclavia sin. , left around arcus aortae Ascend in tracheo-esophageal sulcus Enter larynx behind art. cricothyroidea, and turn into n. laryngeus inferior Supply: laryngeal mucosa below rima glottis, laryngeal muscles except m. cricothyroideus n Rami cardiaci inferiores n Rami tracheales n Rami esophagei Rami bronchiales

Abdominal branches n Rr. gastrici anteriores и posteriores: q q n n Along lesser curvature of stomach supply anterior and posterior walls At antrum pyloricus bracnches for pars pylorica Rr. hepatici: enter plexus hepaticus supply liver and gall bladder Rr. celiaci: for plexus celiacus, reach liver, pancreas, spleen, kidneys and gut to flexura colica sisnistra