1. Cranial Nerves Dr.Haythem Ali Alsayigh

2. 12 pairs of cranial nerves
III to XII attached to brain stem
Their cell bodies form nuclei in the brain stem
First cell body of sensory nerves lie out side CNS
(form ganglia)

3. Summary of cranial nerves
Aspects to study
Position of nucleus
Emerging point from brain stem
Intracranial course
Point of exit from the cranial cavity
Extracranial course
Distribution

4. Few terms: Somatic, branchial and visceral

5. Branchial (Pharyngeal) Arches
ectoderm
endoderm
Core of mesodermal tissue covered by ectoderm and endoderm
Each of the arch will have its own bone/cartilage, muscles, nerve and artery

6. Mandibular branch of trigeminal nerve (V)
Facial nerve (VII)
Premaxilla, maxilla, zygomatic bone, part of temporal bone and mandible
Glossopharyngeal nerve (IX)
Superior laryngeal branch of vagus nerve (X)
Recurrent laryngeal branch of vagus nerve (X)

7. Visceral In relation to internal organs Heart Lung Intestines ………………
……………..

8. Few hints
Nerve A
Nerve B

9. Posterior
Somatic sensory
Visceral sensory
Motor
Sensory
Visceral motor
Somatic motor
Spinal cord (thoracic or lumbar)
Posterior horn
Lateral horn
Anterior horn
Motor
Sensory

10. Brain stem
SpS
GSS SS VS VM BM SM

11. Types of sensations General Visceral sensory Visceral sensory
pain, temperature, touch, viration
position sense
Visceral sensory
Special Visceral sensory
taste
General Somatic sensory
pain, temperature, touch, vibration
position sense
Somatic sensory
Special Somatic sensory
hearing

12. SpS SS VS BM SM VM
SpS SS VS BM SM VM

13. III IV V VI VII XII IX X XI III VII IX VII X IX X V VII IX X VIII SS
GSS VS
VIII SM BM VM
VII IX X V
VII IX X XI

14. Functional components of cranial nerves
III IV
Somatic Motor
Muscles of the orbit (III, IV, VI)
Muscles of tongue (XII) VI
XII

15. Branchial Motor Muscles of mastication (V) Facial muscles (VII)
Pharyngeal and laryngeal muscles (Nucleus ambiguus via IX, X, XI nerves)

16. Visceral Motor Edinger Westphal nucleus (accessory oculomotor)
Salivary nuclei (NI part of VII, IX)
Dorsal motor nucleus of vagus
(for cardiac muscles, smooth muscles of alimentary tract)

17. Sensory Visceral sensory with taste
Consists of single nuclei for visceral and somatic sensory
Visceral sensory with taste
Nucleus of tractus solitarious which receives taste fibres from the tongue through VII, IX
and sensory from heart, lungs and other viscera through X

18. General somatic sensory
Sensory nucleus of trigeminal nerve extending from the midbrain to the cervical spinal cord

19. Special somatic sensory
Hearing via VIII (vestibulocochlear nerve)

20. III IV III VI VII XII IX X V VII IX VII X IX XI X V VII IX X VIII SS
GSS SS VS
VIII BM SM VM
VII IX X V
VII IX X XI

21. Intracranial course and exit

22. 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

24. 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

26. 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

27. Sensory cranial nerves
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

28. 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)
Motor to superior obliquus Ⅵ
Nucleus of abducent nerve (GSE)
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

30. Optic canal
(II)
Superior orbital fissure
(III, IV, V1, VI)
Foramen rotundum
(V2)
Foramen ovale
(V3)
Foramen spinosum
Foramen lacerum
Internal acoustic meatus
(VII, VIII)
Jugular foramen
(IX, X, XI)
Hypoglossal canal
(XII)

31. Olfactory Nerve (I)
Anterior perforated
substance
Olfactory tract
Uncus
Olfactory bulb
Nerve filaments
Cribriform plate of
ethmoid bone
Bypass thalamus and goes directly into the taste area

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

33. Optic Nerve (II) T N

34. Optic Nerve (II) Optic nerve Optic chiasma Optic tract Optic radiation
Superior colliculus
(body reflexes)
Pretectal nucleus
(pupillary reflexes)
Internal
capsule
Lateral geniculate body
of thalamus

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

36. Oculomotor Nerve (III)
Somatic motor nucleus
Visceral motor nucleus
(Edinger westphal nucleus)
Nerve emerges from ventral aspect of midbrain
travel’s in the lateral wall of the cavernous sinus

37. Oculomotor Nerve… cont.
Levator palpabrae superioris
Dilator pupillae
Sympathetic from
Internal carotid plexus
Superior division
Superior rectus
Medial rectus, inferior rectus, inferior oblique
Inferior division
Parasympathetic from
EW nucleus
Ciliary muscle
Sphincter pupillae
Ciliary ganglion

38. Oculomotor nerve Oculomotor nerve Components Main action－supplies
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

39. Accessory nerve
Abducent nerve

40. Trochlear Nerve (IV) Somatic motor nucleus
Emerges from the dorsal aspect of midbrain
Travels in the lateral wall of the cavernous sinus
Supplies the superior oblique muscle

41. Abducens Nerve (VI) Somatic motor nucleus
Nucleus lies in lower pons near midline
Emerge between pons and pyramid of medulla
Travels through the cavernous sinus
Supply the lateral rectus muscle

42. Oculamotor paralysis
Abducent nerve injury

43. Oculomotor N (III) Trochlear N (IV) Abducent N (VI) Ventral midbrain
Lateral wall
Cavernous S
Divide
Sup. & Inf.
divisions
Sup/infraorbital fissure
Trochlear N (IV)
Dorsal
midbrain
Lateral wall
Cavernous S
Superior orbital fissure
Abducent N (VI)
Between
Pons & pyramid of medulla
within
Cavernous S
Superior orbital fissure

44. Cavernous sinus 1- Oculomotor N 2- Trochlear N 3- Abducent N
4- Ophthalmic branch of TN
5- Maxillary branch of TN
6- Sympathetic plexus of N
7- Internal carotid A
8- Pituitary gland

45. LR6(SO4)3

46. Trigeminal nerve (V) Branchial motor nucleus Somatic sensory nucleus
Emerge from the ventral aspect of pons
Sensory and motor roots emerge separately

47. Trigeminal nerve… cont.
Somatic sensory
nucleus
Trigeminal ganglion
Cell bodies of 1st order
SA fibres
Ophthalmic division
Lat. Wall of
cavernous
sinous
Maxillary division
Mandibulardivision
Mandibularnerve
(mixed)
Branchial motor
nucleus
Foramen ovale

48. 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

50. Branches
Ophthalmic nerve (Ⅴ1, sensory) leave the skull through the superior orbital fissure, to enter orbital cavity
Frontal nerve
Supratrochlear nerve
Supraorbital nerve Lacrimal nerve Nasociliary nerve

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

52. Maxillary nerve (Ⅴ2, sensory) Leave skull through foramen rotundum
Branches
Infraorbital nerve
Zygomatic nerve
Superior alveolar nerve
Pterygopalatine nerve

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

54. Mandibular nerve (Ⅴ3, 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

56. 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

57. Facial Nerve (VII) Visceral motor nucleus (Superior salivary nucleus)
Branchial motor nucleus
Visceral motor nucleus
(Superior salivary nucleus)
Taste sensory nucleus (Tractus solitarius)
Main facial nerve and the nervous intermedius parts emerge from the cerebellopontine angle

58. Facial Nerve…cont. Internal acoustic meatus Geniculate ganglion
(taste 1st order cell bodies)
Nucleus of
Tractus solitarious
Chorda tympani
nerve
Taste from anterior tongue
Nervous
intermedius
Branchial motor
nucleus
VE to submandibular gland and glands on the mouth floor
Greater petrosal nerve
Sup. salivary
nucleus
Nerve to stapedius
Ear drum
Stylomastoid foramen
Pure branchial motor facial nerve
Supply muscles of facial expression

59. 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

61. 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

62. 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

63. 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

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

65. Pterygopalatine ganglion: lies in pterygopalatine fossa under maxillary nerve
Submandibular ganglion : lies between lingual nerve and submandibular gland

66. Injury to the facial nerve

67. Vestibulocochlear Nerve (VIII)
Internal acoustic meatus
Spiral ganglion of cochlea
Cochlear nuclei
in pons
Cochlear nerve
Hair cells of spiral organ
Vestibular ganglion
Vestibular nuclei
in medulla
Cerebellopontine angle
Vestibular nerve
Hair cells of utricle, saccule and semilunar canals

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

69. Glossopharyngeal Nerve (IX)
Branchial motor nucleus (Nucleus ambiguus)
supplies stylopharyngeus muscle
Parasympathetic nucleus (Inferior salivary nucleus)
supplies parotid gland
Sensory nuclei
GSS from posterior tongue goes to sensory nucleus of trigeminal nerve
Taste from the posterior tongue goes to the tractus solitarius
VS from baroreceptors go to nucleus of tractus solitarius

70. 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

72. 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

74. Vagus Nerve (X) Branchial motor nucleus (Nucleus ambiguus)
supplies pharyngeal constrictors
Visceral motor nucleus (Dorsal motor nucleus of vagus)
supplies muscles of heart, bronchi, oesophagus, stomach and intestines
Visceral sensory nucleus
VS from larynx, heart, lung… goes to nucleus of tractus solitarius
GSS goes to sensory nucleus of trigeminal nerve

75. 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

77. Course Right vagus nerve 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

78. 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

79. Cervical cardiac branches : descending to terminate in cardiac plexus
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

80. Superior laryngeal nerve
Internal branch
External branch

81. 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

82. 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

83. Accessory Nerve (XI) Branchial motor nerve Somatic motor nerve
Cranial root From nucleus ambiguus
Fibres in the cranial root join the vagus nerve
Somatic motor nerve
Spinal root Anterior horn cells of upper cervical spinal segments
Fibres in the spinal root supply sternocleidomastoid and trapezius muscles

85. Hypoglossal Nerve (XII)
Somatic motor nerve
Leaves cranial cavity through the hypoglossal canal
Supplies all muscles (intrinsic and extrinsic) of tongue except palatoglossus

88. GSA VE BE BA

89. GSA BE BA VE

90. THE END THANKS