The document describes the anatomy of the brain and cranial nerves. It discusses the major structures of the brain including the cerebral cortex with its lobes, brain stem with midbrain, pons and medulla, and cerebellum. It then describes the 12 pairs of cranial nerves, identifying their origin, distribution and function. The cranial nerves include olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, spinal accessory, and hypoglossal nerves. Assessment techniques for cranial nerve function are also briefly outlined.

1. 1
Cranial Nerves

2. 2
Cerebral Cortex
• Two hemispheres
• Separated by longitudinal fissure
• Right and Left hemispheres
• Connected by Corpus Callosum
• Sulci and gyri
• Frontal, parietal, temporal and occipital lobes

3. 3
Brain Stem
• Midbrain
• Pons
• Medulla oblongata
• Midbrain connects the pons and the cerebellum with
the cerebral hemispheres
• Cranial nerves III and IV originate in the midbrain
• Pons in front of cerebellum; between the midbrain and
medulla and is a bridge between the two halves of the
cerebellum and between the medulla and the cerebrum
• Cranial nerves V, VI, VII and VIII originate in the pons
• IX, X, XI and XII have their nuclei in medulla oblongata

4. 4
Cerebellum
• Separated from the cerebral hemispheres by
tentorium cerebelli
• Responsible for coordination of movement –
balance, position, sense (awareness of where
each part of the body is)

5. 5
Cranial Nerves
• 12 pairs
• Emerge from the lower surface of the brain
and pass through the foramina in the skull
• I, II, VIII – sensory
• III, IV ,VI, XI and XII – motor
• V, VII, IX and X are – mixed

6. 6
Cranial Nerves
1. Olfactory – sensory - sense of
smell
2. Optic nerve – sensory – visual
acuity
3. Oculomotor – motor – eye ball
movement, lid movement,
pupillary constriction lens
accommodation

7. 4. Trochlear – motor – muscles that move the
eye
5.Trigeminal – mixed – facial sensation,
mastication
6. Abducens – motor – muscle that move the eye
7. Facial – mixed – facial expression, salivation,
taste
7

8. 8. Vestibulocochlear – sensory – hearing and
equilibrium
9. Glossopharyngeal – mixed – taste, sensation
in the pharynx and tongue, pharyngeal
muscles
10. Vagus – mixed – muscles of pharynx, larynx,
soft palate, thoracic and abdominal viscera –
parasympathetic innervation
11. Spinal accessory – motor –
sternocleidomastoid trapezius muscles.
12. Hypoglossal – motor – movement of the
tongue
8

9. 9
Olfactory nerves
• Nerve of the sense of smell
• Nerve endings and fibres arise in the upper
part of the mucous membrane of the nose
• Pass upwards through the cribriform plate of
ethmoid bone
• These nerves pass to the olfactory bulb
• Thence proceed backwards as the olfactory
tract, to the area of smell in the temporal lobe

10. 10
Optic nerves
• Nerves of the sense of sight
• Fibres originate in the retina
• The fibres combine to form optic nerve
• Optic nerve passes through the optic foramina of the
sphenoid bone
• Join optic chiasma above the pituitary gland
• The nerves proceede backwards as the optic tracts to
the lateral geniculate bodies
• From LGB the impulses pass as optic radiations to the
centre for sight in the occipital lobes and to the
cerebellum
• In the occipital lobe sight is perceived
• The central retinal artery and vein enter the eye
enveloped by the fibres of the optic nerve

11. 11
Oculomotor nerve
• Arises from nerve cells near the cerebral aqueduct.
• It supplies the following extra-ocular muscles : superior
rectus, medial retus, inferior rectus and the inferior
oblique muscles of the eye
• It also supplies the following intra-ocular muscles also
ciliary muscles – shape of lens
circular muscles of the iris – constrict the iris
• It supplies the levator palpebrae muscle – raises the upper
eyelid

12. 12
Trochlear nerve
• This nerve arises from nerve cells near the
cerebral aqueduct.
• It supplies the superior oblique muscle of the
eye which moves the eye ball downwards and
outwards

13. 13
Trigeminal nerve
• Contains motor and sensory fibres
• Chief sensory nerve for the face and head
• Pain temperature and touch
• Motor action on muscles of mastication
• Three main branches -
• The ophthalmic branch – sensory – lacrimal glands,
conjunctiva, forehead, eyelids anterior aspect of scalp
and mucous membrane of the nose
• The maxillary branch – sensory – cheeks, upper gums,
upper teeth aned lower eyelids
• The mandibular branch sensory and motor – teeth and
gums of the lower jaw, pinnas lower lip and tongue –
muscles of mastication

14. 14
Abducent nerve
• From nerve cells lying under the floor of the
fourth ventricle
• supplies lateral rectus muscle

15. 15
Facial nerve
• Motor and sensory
• From nerve cells in the lower part of the pons
• Supplies muscles of facial expression
• Sensations from taste buds on the anterior 2/3
of tongue to the taste perception area in the
cerebral cortex

16. 16
Vestibulocochlear nerve
• Two distinct sets of fibres – vestibular nerves
and cochlear nerves
• Vestibular nerve arises from the semicircular
canals go to cerebellum – associated with the
manitenance of posture and balance
• The cochlear nerve originate in the organ of
Corti – go to hearing areas of the cerebral
cortex.

17. 17
Glossopharyngeal nerve
• From nuclei in the medulla oblongata.
• Motor fibres – muscles of the tongue and
pharynx and secretory cells of the parotid
• Sensory fibres – go to cerebral cortex from
posterior 1/3 of tongue, the tonsils and
pharynx.
• Nerves IX, X and XI go out of the cranium
through the same foramen – the jugular
foramen

18. 18
Vagus nerve
• Arise from nerve cells in the medulla
oblongata and other nuclei
• Pass through neck into the thorax and the
abdomen
• Motor – smooth muscles and secretory glands
of the pharynx, larynx, trachea, heart,
oesophagus, stomach, intestines, pancreas,
gall bladder, bile ducts, spleen, kidneys, ureter
and blood vessels in the thoracic and
abdominal cavities
• Sensory – lining membranes of the above
structures.

19. 19
Accessory nerve
• Arise from nerve cells in the medulla
oblongata and in the spinal cord.
• Supplies sternocleidomastoid and trapezius
muscles
• Branches join the vagus nerve and supply the
pharyngeal and laryngeal muscles

20. 20
Hypoglossal nerve
• Arise from cells in the medulla oblongata
• Supply the muscles of the tongue and muscles
surrounding the hyoid bone and contribute to
swallowing and speech

21. 21
Assessing Cranial Nerve Function
• Olfactory Nerve : identify odors with eyes closed –
coffee etc
• Optic Nerve : snellen eye chart; visual fields :
ophthalmoscopic examination
• Oculomotor Nerve : III, IV and VI : ocular rotations,
conjugate movements, nystagmus. Test for pupillary
reflexes and inspect eyelids for ptosis
• Trochlear
• Abducens
• Trigeminal Nerve :

22. 22

23. 23

24. 24

25. 25

27. 27

28. 28

29. 29
Back

30. 30

31. 31

32. 32

33. 33

34. 34

35. 35

36. 36
Back

37. 37

38. 38

39. 39
Oculomotor
nerve

40. 40

41. 41

42. 42
Brain stem - Cranial nerves -
anterior view
1. Oculomotor nerve CN.III
2. Trochlear nerve CN.IV
3. Transverse pontine vein
4. Abducent nerve CN.VI
5. Trigeminal nerve CN.V
6. Facial and
vestibulocochlear
nerves CN.VII/VIII
7. Glossopharyngeal nerve
CN.IX
8. Vagus nerve CN.X
9. Accesory nerve -spinal
part CN.XI
10. Hypoglossal nerve
CN.XII
11. Anterior cerebellar vein

43. 43
41,
42,
46,
44,
45,
46

44. 44
Trigeminal nerve
Trigeminal
nerve

45. 45

46. 46
T
R
I
G
E
M
I
N
A
L
N
E
R
V
E

47. 47

48. 48

49. 49

50. 50

51. 51
Facial nerve

52. 52

53. 53

54. 54
Back

55. 55
Glosso
pharyngeal
nerve

56. 56

57. 57

58. 58

59. 59

60. 60

61. 61

62. 62

63. 63
back

64. 64

65. 65

66. 66
back

67. 67
Back

68. 68
olfactory

69. 69
Back

70. 70

71. 71
The End

72. 72
a) Frontal bone.
b) Frontal sinus.
c) Internal frontal spine.
d) Foramen caecum.
e) Crista galli.
f) Frontal bone, orbital portion.
g) Cellulae of the ethmoidal bone.
h) Body of the sphenoid bone.
i) Greater wing of the sphenoid bone.
k) Occipital bone, basilar portion.
l) Temporal bone, squamous portion.
m) Temporal bone, petrous portion.
n) Optic foramen.
o) Foramen rotundum.
p) Foramen ovale.
q) Foramen spinosum.
r) Superior orbital fissure.
s) Tympanic cavity.
t) Internal auditory meatus (broken open from above).
u) Malleus, hammer (s. capitulum).
v) Incus (s. ambos).
w) Cochlea.
x) Superior semicircular canal.
y) Ocular bulb.
z) Lacrimal gland.
a) m. Lateral rectus.
b) m. Levator palpebrae superioris.
g) m. Superior rectus.
d) m. Superior oblique.
d*) Trochlea for superior oblique.
e) m. Medial rectus.
z) m. Temporalis (medial surface).
h) m. Lateral pterygoid.
q) Hypophysis (pituitary gland).
i) Foramen magnum.
k) Jugular foramen.
l) Hypoglossal canal (s. Anterior condyloid foramen).
m) Occipital bone (fossae cerebelli).
n) Transverse sinus.
1. middle meningeal artery (branch of the maxillary artery).
2. internal carotid artery.
3. lacrymal artery.
4. artery, muscle branch.
5. supraorbital artery.
6. ethmoidal artery.
7. ophthalmic artery.
8. optic nerve (CN II).
9. oculomotor nerve (CN III).
10. trochlear nerve (CN IV).
11. trigeminal nerve (CN V).

73. 73
23. zygomatic branch, lacrymal nerve.
24. lacrymal branch, lacrymal nerve.
25. ciliary nerves (from the ciliary ganglion [s. ganglion opthalmicum]).
26. nerve to the m. buccinator.
27. deep temporal nerve.
28. nerve to the m. masseter.
29. superficial temporal nerve (s. auricularis anterior nerve).
30. maxillary artery.
31. nerves of the external auditory meatus.
32. chorda tympani (of facial nerve).
33. petrosus minor nerve [NA] (s. lesser superficial petrosal nerve).
34. petrosus major nerve [NA] (s. greater superficial petrosal nerve, nervus Vidianus, nervus petrosus superficialis
major) [carried in the genu of the facial nerve].
35. abducens nerve (CN VI).
36. facial nerve (CN VII) inner half of the internal auditory meatus.
37. genu (facial nerve).
38. facial nerve in the Fallopian canal.
39. cochlear nerve (CN VIII).
40. vestibular nerve (CN VIII).
41. glossopharyngeal nerve (CN IX).
42. vagus nerve (CN X).
43. spinal accessory nerve of Willis (CN XI).
44. hypoglossal nerve (CN XII).
45. vertebral artery.

74. 74

75. 75