The Cranial Nerves & Spinal nerves. Departemen Anatomi Fakultas Kedokteran USU

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1 The Cranial Nerves & Spinal nerves Departemen Anatomi Fakultas Kedokteran USU Names of cranial nerves ⅠOlfactory nerve ⅡOptic nerve ⅢOculomotor nerve Ⅳ Trochlear nerve ⅤTrigeminal nerve ⅥAbducent nerve ⅦFacial nerve ⅧVestibulocochlear nerve Ⅸ Glossopharyngeal nerve ⅩVagus nerve ⅪAccessory nerve Ⅻ Hypoglossal nerve 1

2 Classification of cranial nerves Sensory cranial nerves: contain only afferent (sensory) fibers ⅠOlfactory nerve ⅡOptic nerve Ⅷ Vestibulocochlear nerve Motor cranial nerves: contain only efferent (motor) fibers ⅢOculomotor nerve ⅣTrochlear nerve ⅥAbducent nerve ⅪAccessory nerv Ⅻ Hypoglossal nerve Mixed nerves: contain both sensory and motor fibers--- ⅤTrigeminal nerve, Ⅶ Facial nerve, ⅨGlossopharyngeal nerve ⅩVagus nerve Sensory cranial nerves N. Location of cell body and axon categories Ⅰ Ⅱ Ⅷ Olfactory cells (SVA) Ganglion cells (SSA) Vestibular ganglion(ssa) Cochlear ganglion (SSA) Cranial exit Cribrifom foramina Optic canal Internal acoustic meatus Terminal nuclei Olfactory bulb Lateral geniculate body Vestibular nuclei Cochlear nuclei Main action Smell Vision Equilibri um Hearing 2

3 Olfactory nerve Olfactory mucosa (SVA) Cribriform foramina Olfactory bulb Optic nerve Ganglion cell (SSA) Optic canal Lateral geniculate body 3

4 Vestibulocochlear nerve Vestibular ganglion(ssa) Vestibular nuclei Internal acoustic meatus Cochlear ganglion (SSA) Cochlear nuclei Motor cranial nerves N. Nucleus of origin and axon categories Ⅲ Ⅳ Ⅵ Ⅺ Ⅻ Nucleus of oculomotor (GSE) Accessory nucleus of oculomotor (GVE) Nucleus of trochlear nerve (GSE) Nucleus of abducent nerve (GSE) Nucleus of accessory nerve (SVE) Nucleus of hypoglossal nerve( GSE) Cranial exit Superior orbital fissure Superior orbital fissure Superior orbital fissure Jugular foramen Hypoglossal canal Main action Motot to superior, inferior and medial recti; inferior obliquus; levator palpebrae superioris Parasympathetic to sphincter pupillea and ciliary muscl Motor to superior obliquus Motor to lateral rectus Motor to sternocleidomastoid and trapezius Motot to muscles of tongue 4

5 Oculomotor nerve Components General somatic efferent fibers (GSE) General visceral efferent fibers (GVE) Main action-supplies Superior, inferior and medial recti; inferior obliquus; levator palpebrae superioris Sphincter pupillea and ciliary muscle Ciliary ganglion: lies between optic nerve and lateral rectus Oculomotor nerve 5

6 Accessory nerve Abducent nerve Hypoglossal nerve Hypoglossal nerve 6

7 Oculamotor paralysis Abducent nerve injury Mixed cranial nerves 7

8 Trigeminal nerve Components of fibers SVE fibers: originate from motor nucleus of trigeminal nerve, and supply masticatory muscles GSA fibers: transmit facial sensation to sensory nuclei of trigeminal nerve, the GSA fibers have their cell bodies in trigeminal ganglion, which lies on the apex of petrous part of temporal bone 8

9 Branches Ophthalmic nerve(Ⅴ1, sensory) leave the skull through the superior orbital fissure, to enter orbital cavity Branches Frontal nerve: Supratrochlear nerve Supraorbital nerve Lacrimal nerve Nasociliary nerve Distribution: Sensation from cerebral dura mater Visual organ Mucosa of nose Skin above the eye and back of nose 9

10 Maxillary nerve(Ⅴ2, sensory) Leave skull through foramen rotundum Branches Infraorbital nerve Zygomatic nerve Superior alveolar nerve Pterygopalatine nerve Distribution: Sensation from cerebral dura mater Maxillary teeth Mucosa of nose and mouth Skin between eye and mouth 10

11 Mandibular nerve(Ⅴ3, mixed) Leave the skull through the foramen ovaleto enter the infratemporal fossa Branches Auriculotemporal nerve Buccal nerve Lingual nerve Inferior alveolar nerve Nerve of masticatory muscles 11

12 Distribution: Sensation from cerebral dura mater Teeth and gum of lower jaw Mucosa of floor of mouth Anterior 2/3 of tongue Skin of auricular and temporal regions and below the mouth Motor to masticatory muscles, mylohyoid, and anterior belly of digastric Facial nerve (Ⅶ) Components of fibers SVEfibers originate from nucleus of facial nerve, and supply facial muscles GVEfibers derived from superior salivatory nucleus and relayed in pterygopalatine ganglion and submandibular ganglion. The postganglionic fibers supply lacrimal, submandibular and sublingual glands SVAfiber from taste buds of anterior two-thirds of tongue which cell bodies are in the geniculate ganglion of the facial nerve and end by synapsing with cells of nucleus of solitary tract GSA fibers from skin of external ear 12

13 Course: leaves skull through internal acoustic meatus, facial canal and stylomastoid foramen, it then enters parotid gland where it divides into five branches which supply facial muscles 13

14 Branches within the facial canal Chorda tympani : joins lingual branch of mandibular nerve To taste buds on anterior two-thirds of tongue Relayed in submandibular ganglion, the postganglionic fibers supply submandibular and sublingual glands Greater petrosal nerve: GVE fibers pass to pterygopalatine ganglion and there relayed through the zygomatic and lacrimal nerves to lacrimal gland Stapedial nerve : to stapedius 14

15 2/11/2011 Branches outside of facial canal Temporal Zygomatic Buccal Marginal mandibular Cervical Pterygopalatine ganglion : lies in pterygopalatine fossa under maxillary nerve Submandibular ganglion : lies between lingual nerve and submandibular gland 15

16 Injury to the facial nerve Glossopharyngeal nerve (Ⅸ) Components of fibers SVE fibers: originate from nucleus ambiguus, and supply stylopharygeus GVEfibers: arise from inferior salivatory nucleus and ralyed in otic ganglion, the postganglionic fibers supply parotid gland SVAfibers: arise from the cells of inferior ganglion, the central processes of these cells terminate in nucleus of solitary tract, the peripheral processes supply the taste buds on posterior third of tongue GVA fibers: visceral sensation from mucosa of posterior third of tongue, pharynx, auditory tube and tympanic cavity, carotid sinus and glomus, and end by synapsing with cells of nucleus of solitary tract GSAfibers: sensation from skin of posterior surface of auricle and 16

17 Course: leaves the skull via jugular foramen Branches Lingual branches : to taste buds and mucosa of posterior third of tongue Pharyngeal branches : take part in forming the pharyngeal plexus Tympanic nerve : GVE fibers via tympanic and lesser petrosal nerves to otic ganglion, with postganglionic fibers via auriculotemporal (Ⅴ3) to parotid gland Carotid sinus branch : innervations to both carotid sinus and glomus Others: tonsillar and stylophayngeal branches Otic ganglion : situated just below foramen ovale 17

18 Vagus nerve (Ⅹ) components of fibers GVEfibers: originate from dorsal nucleus of vagus nerve, synapse in parasympathetic ganglion, short postganglionic fibers innervate cardiac muscles, smooth muscles and glands of viscera SVEfibers: originate from ambiguus, to muscles of pharynx and larynx GVA fibers: carry impulse from viscera in neck, thoracic and abdominal cavity to nucleus of solitary tract GSAfiber: sensation from auricle, external acoustic meatus and cerebral dura mater 18

19 Course Exits the skull from jugular foramen Descends in the neck in carotid sheath between internal (or common) carotid artery and internal jugular vein Right vagus nerve Enter thoracic inlet on right side of trachea Travels downward posterior to right brachiocephalic vein and superior vena cava Passes posterior to right lung root Forms posterior esophageal plexus Forms posterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity, then divides into posterior gastric and celiac branches 19

20 Left vagus nerve Enter thoracic inlet between left common carotid and left subclavian arteries, posterior to left brachiocephalic vein Crosses aortic arch where left recurrent laryngeal nerve branches off Passes posterior to left lung root Forms anterior esophageal plexus Forms anterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity, then divides into anterior gastric and hepatic branches Branches in neck Superior laryngeal nerve: passes down side of pharynx and given rise to Internal branch, which pierces thyrohyoid membrane to innervates mucous membrane of larynx above fissure of glottis External branch, which innervates cricothyroid Cervical cardiac branches : descending to terminate in cardiac plexus Others: auricular, pharyngeal and meningeal branches 20

21 Superior laryngeal nerve Internal branch External branch Branches in thorax Recurrent laryngeal nerves Right one hooks around right subclavian artery, left one hooks aortic arch Both ascend in tracheo-esophageal groove Nerves enter larynx posterior to cricothyroid joint, the nerve is now called inferior laryngeal nerve Innervations: laryngeal mucosa below fissure of glottis, all laryngeal laryngeal muscles except cricothyroid Bronchial and esophageal branches 21

22 Branches in abdomen Anterior and posterior gastric branches Run close to lesser curvature and innervate anterior and posterior surfaces of stomach As far as pyloric antrum to fan out into branches in a way like the digits of a crow s foot to supply pyloric part Hepatic branches: join hepatic plexus and then supply liver and gallbladder Celiac branches: send branches to celiac plexus to be distributed with sympathetic fibers to liver, pancreas, spleen, kidneys, intestine as far as left colic flexure Spinal Nerves Thirty-one pairs of spinal nerves First pair exit vertebral column between skull and atlas (C1) Last four pair exit via the sacral foramina Others exit through intervertebral foramina Eight pair cervical, twelve pair thoracic, five pair lumbar, five pair sacral, one pair coccygeal 22

23 Dermatomal Map Spinal nerves indicated by capital letter and number Dermatomalmap: skin area supplied with sensory innervation by spinal nerves Spinal Nerves Medially, give rise to the roots that attach the nerve to the s.c. Laterally, give rise to the rami that innervate the dorsal and ventral regions of the body Dorsal ramus Contains both sensory and motor neurons that innervate the dorsal regions of the body Ventral ramus Contains both sensory and motor neurons that innervate the ventral regions of the body Braid together to form plexuses (plexi) 23

24 Branches of Spinal Nerves Dorsal Ramus: innervate deep muscles of the trunk responsible for movements of the vertebral column and the C.T. and skin near the midline of the back. Ventral Ramus: what they innervate depends upon which part of the spinal cord is considered. Thoracic region: form intercostal nerves that innervate the intercostal muscles and the skin over the thorax Remaining spinal nerve ventral rami form five plexuses (intermingling of nerves). Ventral rami of C1-C4= cervical plexus Ventral rami of C5-T1= brachial plexus Ventral rami of L1-L4= lumbar plexus Ventral rami of L4-S4= sacral plexus Ventral rami of S4 and S5= coccygeal plexus Communicating Rami: communicate with sympathetic chain of ganglia. Cervical Plexus Formed by ventral rami of spinal nerves C1-C4 Motor: Innervates muscles of the neck (SCM, trapezius), laryngeal muscles Sensory: Skin of upper chest, shoulder, neck, and ear Phrenic nerve From C3-C5 (cervical and brachial plexuses) Innervates diaphragm 24

25 Brachial Plexus Formed by ventral rami of spinal nerves C5-T1 Five ventral rami form three trunks that separate into six divisions then form cords that give rise to: (RTDC) Branches/nerves Axillary Radial Musculocutaneous Ulnar Median Brachial Plexus: Axillary Nerve Motor: Innervates deltoid and teres minor Deltoid -Abducts arm Teres -Laterally rotate arm Sensory: from skin of the lateral shoulder 25

26 Brachial Plexus: Radial Nerve Motor: Stimulates extensor muscles of arm, forearm, and hand Triceps, supinator, brachioradialis, ECR, ECU, and some extensors of the fingers (extensor digitorum) Cause extension movements at elbow and wrist, thumb movements Sensory: From skin on posterior surface of arm and forearm, lateral 2/3 of dorsum of hand Damage due to compression results in crutch paralysis Major symptom is wrist drop Failure of extensors of wrist and fingers to function Elbow, wrist, and fingers constantly flexed Brachial Plexus: Musculocutaneous Nerve Motor: Stimulates flexors in anterior arm: (biceps brachii, brachialis) Causes flexion movements at shoulder and elbow Sensory: From skin along lateral surface of forearm 26

27 Brachial Plexus: Ulnar Nerve Motor: Stimulates flexor muscles in anterior forearm (FCU, FDP, most intrinsic muscles of hand) Results in wrist and finger flexion Sensory: From skin on medial surface of hand, little finger, and medial surface of ring finger Most easily damaged Hitting the funny bone excites it Brachial Plexus: Median Nerve Motor: Innervates all but one of the flexors of the wrist and fingers, and thenarmuscles at base of thumb (Palmaris longus, FCR, FDS, FPL, pronator) Causes flexion of the wrist and fingers and thumb Sensory: From skin of anterolateral2/3 palm, thumb, index and middle fingers; lateral surface of ring finger Damaged in carpal tunneland suicide attempts 27

28 Lumbar plexus: formed by ventral rami of spinal nerves L1-L4 Sacral plexus: formed by ventral rami of L4-S4 Usually considered together because of their close relationship Four major nerves exit and enter lower limb Obturator Femoral Tibial Common fibular (peroneal) Lumbosacral Plexus Lumbar Plexus:Obturator Nerve Motor: Innervates adductor group and gracilis Causes adduction of the thigh and knee (gracilis) Sensory: From skin of the superior medial side of thigh 28

29 Lumbar Plexus: Femoral Nerve Motor: Innervates anterior muscles of thigh Quadriceps group and sartorius Cause extension of the knee Innervates flexors and adductors of hip: Pectineus and Iliopsoas Cause flexion of the hip Sensory: From skin of the anterior and lateral thigh; medial surface of leg and foot Sacral Plexus: Sciatic Nerve Thickest and longest nerve of the body Innervates posterior thigh and entire lower leg Composed of 2 nerves (tibial n. and common fibular nerve (or peroneal nerve) in a common sheath) Leaves pelvis via greater sciatic notch Courses deep to gluteus and enters posterior thigh just medial to the hip joint The 2 divisions diverge just above the knee. Sciatic Nerve Injury May be due to fall, disc herniation, impro-per administration of injection into buttock When transected, leg is nearly useless Leg cannot be flexed (hamstrings paralyzed) All foot and ankle movement is lost Foot drops into plantar flexion (footdrop) 29

30 Tibial Nerve Tibial Innervates muscles of: Posterior thigh -hamstrings (knee flexors, hip extensors) Posterior leg(gastrocnemius, - plantar flexors; FDL, FHL - toe flexors) Branches in foot to form medial and lateral plantar nerves Tibial nerve injury, paralyzed calf muscles - cannot plantar flex foot;shuffling gait develops Common Fibular (Peroneal) Nerve Common Fibular Nerve Innervates anterior and lateral muscles of the leg and foot Extensors that dorsiflex the foot- Tibialis anterior, EDL, EHL) Sensory: From skin of the lateral and anterior leg and dorsum of the foot. Common fibular nerve is susceptible to injury because of its superficial location at the head and neck of the fibula. Tight leg cast, remaining too long in a sidelying position on a firm mattress may compress this nerve and result in footdrop 30

31 Other Nerves of the Lumbosacral Plexus Nerves that innervate the skin of the suprapubic area, external genitalia, superior medial thigh, posterior thigh Iliohypogastric nerve -Muscles of abdominal wall and pubic region Genitofemoral nerve -Skin of scrotum (males) and labia (females); inferior abdominal muscles Pudendal nerve -innervates muscles and skin of the perineum (region encompasssing external genitalia and anus); external anal sphincter; mediates erection, and is involved in voluntary control of urination; the shameful nerve Coccygeal Plexus S4-S5; coccygeal nerve Muscles of pelvic floor Sensory information from skin over coccyx 31

32 Nature of Somatic Reflexes Quick, involuntary, stereotyped reactions of glands or muscle to sensory stimulation automatic responses to sensory input that occur without our intent or often even our awareness Functions by means of a somatic reflex arc stimulation of somatic receptors afferent fibers carry signal to dorsal horn of spinal cord one or more interneurons integrate the information efferent fibers carry impulses to skeletal muscles skeletal muscles respond The Muscle Spindle Sense organ (proprioceptor) that monitors length of muscle and how fast muscles change in length Composed of intrafusalmuscle fibers, afferent fibers and gamma motorneurons 32

33 Stretch Reflex Flexor Withdrawal Reflexes Occurs during withdrawal of foot from pain Polysynaptic reflex arc Neural circuitry in spinal cord controls sequence and duration of muscle contractions 33

34 Crossed Extensor Reflexes Maintains balance by extending other leg Intersegmental reflex extends up and down the spinal cord Contralateral reflex arcs explained by pain at one foot causes muscle contraction in other leg Relationship of Brain and Spinal Cord Reflexes Sensory information goes to brain; e.g., pain. Descending tracts convey motor impulses from brain to effectors. 34