The Cranial Nerves

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The Cranial Nerves

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Names of cranial nerves

• ? Olfactory nerve
• ? Optic nerve
• ? Oculomotor nerve
• ? Trochlear nerve
• ? Trigeminal nerve
• ? Abducent nerve
• ? Facial nerve
• ? Vestibulocochlear nerve
• ? Glossopharyngeal nerve
• ? Vagus nerve
• ? Accessory nerve
• ? Hypoglossal nerve

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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

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Classification of cranial nerves

• Sensory cranial nerves contain only afferent
  (sensory) fibers
• ?Olfactory nerve
• ?Optic nerve
• ? Vestibulocochlear nerve
• Motor cranial nerves contain only efferent
  (motor) fibers
• ? Oculomotor nerve
• ? Trochlear nerve
• ?Abducent nerve
• ? Accessory nerv
• ? Hypoglossal nerve
• Mixed nerves contain both sensory and motor
  fibers---
• ?Trigeminal nerve,
• ? Facial nerve,
• ?Glossopharyngeal nerve
• ?Vagus nerve

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

• Olfactory mucosa (SVA)? Cribriform foramina ?
  Olfactory bulb

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Optic nerve

• Ganglion cell (SSA) ? Optic canal ? Lateral
  geniculate body

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Vestibulocochlear nerve

• Vestibular ganglion(SSA) ?
  ? Vestibular nuclei
• 
  Internal acoustic meatus
• Cochlear ganglion (SSA) ?
  ? Cochlear nuclei

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Motor cranial nerves
N. Nucleus of origin and axon categories Cranial exit Main action
? Nucleus of oculomotor (GSE) Superior orbital fissure Motot to superior, inferior and medial recti inferior obliquus levator palpebrae superioris
? Accessory nucleus of oculomotor (GVE) Superior orbital fissure Parasympathetic to sphincter pupillea and ciliary muscl
? Nucleus of trochlear nerve (GSE) Superior orbital fissure Motor to superior obliquus
? Nucleus of abducent nerve (GSE) Superior orbital fissure Motor to lateral rectus
? Nucleus of accessory nerve (SVE) Jugular foramen Motor to sternocleidomastoid and trapezius
? Nucleus of hypoglossal nerve( GSE) Hypoglossal canal Motot to muscles of tongue
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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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Accessory nerve
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Hypoglossal nerve
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Oculamotor paralysis
Abducent nerve injury
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Mixed cranial nerves
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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 ??? (?1, sensory) leave
  the skull through the superior orbital fissure,
  to enter orbital cavity
• Branches
• Frontal nerve???
• Supratrochlear nerve ?????
• Supraorbital nerve ????
• Lacrimal nerve ????
• Nasociliary nerve ????

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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 ????(?2, sensory)
• Leave skull through foramen rotundum
• Branches
• Infraorbital nerve ????
• Zygomatic nerve ???
• Superior alveolar nerve ?????
• Pterygopalatine nerve ????

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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 (?3, mixed) ????
• Leave the skull through the foramen ovale to
  enter the infratemporal fossa
• Branches
• Auriculotemporal nerve ????
• Buccal nerve ???
• Lingual nerve ???
• Inferior alveolar nerve?????
• Nerve of masticatory muscles ?????

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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

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Facial nerve (?)

• 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 ?? 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???? GVE fibers pass to
  pterygopalatine ganglion ????? and there relayed
  through the zygomatic and lacrimal nerves to
  lacrimal gland
• Stapedial nerve ????? to stapedius

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

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• Pterygopalatine ganglion ????? lies in
  pterygopalatine fossa under maxillary nerve
• Submandibular ganglion ?????? lies between
  lingual nerve and submandibular gland

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Injury to the facial nerve
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Glossopharyngeal nerve (?)

• 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 ?? 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 (?3)
  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

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Vagus nerve (?)

• 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
Internal branch
External 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 crows 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