Cranial nerves

The Cranial Nerves: 

The Cranial Nerves 山东大学医学院 解剖教研室 李振华

Names of cranial nerves: 

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

Functional components: 

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

Classification of cranial nerves: 

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

Sensory cranial nerves: 

Sensory cranial nerves N. Location of cell body and axon categories Cranial exit Terminal nuclei Main action Ⅰ Olfactory cells (SVA) Cribrifom foramina Olfactory bulb Smell Ⅱ Ganglion cells (SSA) Optic canal Lateral geniculate body Vision Ⅷ Vestibular ganglion(SSA) Internal acoustic meatus Vestibular nuclei Equilibrium Cochlear ganglion (SSA) Cochlear nuclei Hearing

Olfactory nerve: 

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

Optic nerve: 

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

Vestibulocochlear nerve: 

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

Motor cranial nerves: 

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

Oculomotor nerve: 

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

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Abducent nerve Accessory nerve

Hypoglossal nerve : 

Hypoglossal nerve Hypoglossal nerve

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Oculamotor paralysis Abducent nerve injury

Mixed cranial nerves: 

Mixed cranial nerves

Trigeminal nerve: 

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

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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

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

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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

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

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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

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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): 

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

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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

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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

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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

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Branches outside of facial canal Temporal Zygomatic Buccal Marginal mandibular Cervical

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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

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Injury to the facial nerve

Glossopharyngeal nerve (Ⅸ): 

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

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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

Vagus nerve (Ⅹ): 

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

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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

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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

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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

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Superior laryngeal nerve External branch Internal branch

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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

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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