The Cranial Nerves

1. The Cranial Nerves 山东大学医学院 解剖教研室 李振华

2. Names of cranial nerves • Ⅰ Olfactory nerve • Ⅱ Optic nerve • Ⅲ Oculomotor nerve • Ⅳ Trochlear nerve • Ⅴ Trigeminal nerve • Ⅵ Abducent nerve • Ⅶ Facial nerve • Ⅷ Vestibulocochlear nerve • Ⅸ Glossopharyngeal nerve • Ⅹ Vagus nerve • Ⅺ Accessory nerve • Ⅻ Hypoglossal nerve

3. Functional components • General somatic afferent fibers (GSA): transmit exteroceptive and proprioceptive impulses from head and face to somatic sensory nuclei • Special somatic afferent fibers (SSA): transmit sensory impulses from special sense organs of vision, equilibrium and hearing to the brain • General visceral afferent fibers (GVA): transmit interoceptive impulses from the viscera to the visceral sensory nuclei • Special visceral afferent fibers (SVA): transmit sensory impulses from special sense organs of smell and taste to the brain • General somatic efferent fibers (GSE): innervate skeletal muscles of eye and tongue • Special visceral efferent fibers (SVE): transmit motor impulses from the brain to skeletal muscles derived from brachial (gill) arches of embryo. These include the muscles of mastication, facial expression and swallowing • General visceral efferent fibers (GVE): transmit motor impulses from the general visceral motor nuclei and relayed in parasympathetic ganglions. The postganglionic fibers supply cardiac muscles，smooth muscles and glands

4. 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 • Ⅲ Oculomotor nerve • Ⅳ Trochlear nerve • ⅥAbducent nerve • Ⅺ Accessory nerv • Ⅻ Hypoglossal nerve • Mixed nerves: contain both sensory and motor fibers--- • ⅤTrigeminal nerve, • Ⅶ Facial nerve, • ⅨGlossopharyngeal nerve • ⅩVagus nerve

5. Sensory cranial nerves

6. Olfactory nerve Olfactory mucosa (SVA)→ Cribriform foramina → Olfactory bulb

7. Optic nerve Ganglion cell (SSA) → Optic canal → Lateral geniculate body

8. Vestibulocochlear nerve Vestibular ganglion(SSA)↘↗Vestibular nuclei Internal acoustic meatus Cochlear ganglion (SSA)↗↘Cochlear nuclei

9. Motor cranial nerves

11. 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

12. Abducent nerve Accessory nerve

13. Hypoglossal nerve Hypoglossal nerve

14. Oculamotor paralysis Abducent nerve injury

15. Mixed cranial nerves

16. 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

18. Branches • Ophthalmic nerve眼神经(Ⅴ1, sensory) leave the skull through the superior orbital fissure, to enter orbital cavity • Branches • Frontal nerve额神经: • Supratrochlear nerve 滑车上神经 • Supraorbital nerve 眶上神经 • Lacrimal nerve 泪腺神经 • Nasociliary nerve 鼻睫神经

19. Distribution: • Sensation from cerebral dura mater • Visual organ • Mucosa of nose • Skin above the eye and back of nose

20. Maxillary nerve上颌神经(Ⅴ2, sensory) • Leave skull through foramen rotundum • Branches • Infraorbital nerve 眶下神经 • Zygomatic nerve 颧神经 • Superior alveolar nerve 上牙槽神经 • Pterygopalatine nerve 翼腭神经

21. Distribution: • Sensation from cerebral dura mater • Maxillary teeth • Mucosa of nose and mouth • Skin between eye and mouth

22. Mandibular nerve(Ⅴ3, mixed) 下颌神经 • Leave the skull through the foramen ovale to enter the infratemporal fossa • Branches • Auriculotemporal nerve 耳颞神经 • Buccal nerve 颊神经 • Lingual nerve 舌神经 • Inferior alveolar nerve下牙槽神经 • Nerve of masticatory muscles咀嚼肌神经

24. 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

25. Facial nerve (Ⅶ) Components of fibers • SVE fibers originate from nucleus of facial nerve, and supply facial muscles • GVE fibers derived from superior salivatory nucleus and relayed in pterygopalatine ganglion and submandibular ganglion. The postganglionic fibers supply lacrimal, submandibular and sublingual glands • SVA fiber 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

27. 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

28. Branches within the facial canal • Chorda tympani 鼓索: 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

29. Greater petrosal nerve岩大神经: GVE fibers pass to pterygopalatine ganglion 翼腭神经节and there relayed through the zygomatic and lacrimal nerves to lacrimal gland • Stapedial nerve 镫骨肌神经: to stapedius

30. Branches outside of facial canal • Temporal • Zygomatic • Buccal • Marginal mandibular • Cervical

31. Pterygopalatine ganglion翼腭神经节: lies in pterygopalatine fossa under maxillary nerve • Submandibular ganglion下颌下神经节: lies between lingual nerve and submandibular gland

32. Injury to the facial nerve

33. Glossopharyngeal nerve (Ⅸ) Components of fibers • SVE fibers: originate from nucleus ambiguus, and supply stylopharygeus • GVE fibers: arise from inferior salivatory nucleus and ralyed in otic ganglion, the postganglionic fibers supply parotid gland • SVA fibers: 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 • GSA fibers: sensation from skin of posterior surface of auricle and

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

37. Vagus nerve (Ⅹ) components of fibers • GVE fibers: originate from dorsal nucleus of vagus nerve, synapse in parasympathetic ganglion, short postganglionic fibers innervate cardiac muscles, smooth muscles and glands of viscera • SVE fibers: 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 • GSA fiber: sensation from auricle, external acoustic meatus and cerebral dura mater

39. 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

40. 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

41. 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

42. Superior laryngeal nerve Internal branch External branch

43. 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

44. 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