BRIEF INTRODUCTION AND OVERVIEW ABOUT THE ORIGIN, STRUCTURE, ATTACHMENTS AND FUNCTIONS OF THE CRANIAL NERVES FROM HUMAN NERVOUS SYSTEM.

1. CRANIAL NERVES :
ANATOMY

2. INTRODUCTION
 Twelve pairs
 Pass through or into the cranial bones
(thus cranial nerves)
 Numbered I to XII roughly in order from
top (rostral) to bottom (caudal)
 Some cranial nerves contain only sensory
fibres, some contain only motor fibres,
and some contain both.

3.  Some cranial nerves convey parasympathetic
fibres, some convey taste fibres, some convey
both, and some neither
 Olfactory and optic nerves are not “proper”
nerves
 I and II are attached to the cerebral hemispheres
 III to XII to are attached to the brain stem
(midbrain, pons and medulla)

4. CRANIAL NERVES
NAME TYPE PRNCIPAL FUNCTION
I Olfactory Sensory Smell
II Optic Sensory Vision
III Oculomotor Motor Movt of eyeballs
IV Trochlear Motor Movt of eyeballs

5. NAME TYPE PRNCIPAL FUNCTION
V Trigeminal
Va: Ophthalmic
Vb: Maxillary
Vc: Mandibular
Va: Sensory
Vb: Sensory
Vc: Mixed
Va: Sensation from eyeball,
anterior scalp, upper face
Vb: Sensation from nasal cavity
and sinuses, palate, mid face,
maxillary teeth
Vc: Muscles of mastication,
tensor tympani
Sensation from chin, temple, oral
cavity, tongue, TM Joint,
mandibular teeth, ear,
proprioception from muscles of
mastication
VI Abducens Motor Movements of eyeball:
lateral rectus muscle
VII Facial Mixed Muscles of facial expression,
stapedius (middle ear)
(parasympathetic: lacrimal,

6. NAME TYPE PRNCIPAL FUNCTION
IX Glossopharyngeal Mixed Sensation from oropharynx,
posterior tongue, carotid body
and sinus
(taste: posterior tongue)
(muscle: stylopharyngeus)
(parasympathetic: parotid gland)
X Vagus Mixed Muscles of larynx, pharynx
(phonation, swallowing)
Sensation from larynx,
hypopharynx, heart, lungs,
abdominal viscera
(taste: epiglottic region,
hypopharynx)
(parasympathetic: cardiac
muscle; muscles and glands of
foregut and
midgut: intestinal activity)
XI Accessory Motor Muscles: sternocleidomastoid,
trapezius

7. DEVELOPMENT
 Forebrain:
1. Telencephalon (the cerebral
hemispheres) and
2. Diencephalon (the thalamic structures
surrounding the third ventricle)
 Midbrain, or mesencephalon
 Hindbrain: pons, cerebellum and
medulla

9. ATTACHMENTS OF
CRANIAL NERVES
 Forebrain
Cranial n. I
 Telencephalon: limbic system
Cribriform plate (ethmoid)
Cranial n. II
 Diencephalon: lateral geniculate
body  Optic canal (sphenoid)

10.  Midbrain
Cranial n. III
 Upper midbrain (ventral):
Interpeduncular fossa  Superior orbital
fissure (sphenoid)
Cranial n. IV
 Lower midbrain (dorsal): below inferior
colliculi  Superior orbital fissure
(sphenoid)

11.  Hindbrain
Cranial n. V
 Pons (lateral aspect) 
Va: superior orbital fissure (sphenoid)
Vb: foramen rotundum (sphenoid)
Vc: foramen ovale (sphenoid)
Cranial n. VI
 Pontomedullary junction (Near midline)
 Superior orbital fissure (sphenoid)

12. Cranial n. VII
 Pontomedullary junction
(Cerebellopontine angle )  Internal
acoustic meatus, facial canal, stylomastoid
foramen (temporal)
Cranial n. VIII
 Pontomedullary junction
(Cerebellopontine angle )  Internal
acoustic meatus (Temporal)

13. Cranial n. IX, X, XI
 Medulla (Rootlets, lateral to inferior
olive, extending down to cervical cord)
 Jugular foramen (between occipital
and temporal bones)
Cranial n. XII
 Medulla ( Rootlets between pyramid
and olive)  Hypoglossal canal
(occipital)

16. TYPES OF NERVE FIBRE
WITHIN CRANIAL NERVES
 Motor nerves:
voluntary/involuntary
 Motor nerves:
somatic/visceral
 Sensory nerves:
somatic/visceral

17. GANGLION AND NUCLEUS
 Easily confused
 Both contain nerve cell bodies
 Some cranial nerves are associated
with both a ganglion and a nucleus
with the same name
 Example, the trigeminal nerve (V) is
associated with the trigeminal
ganglion and several trigeminal nuclei

18.  In a nerve, ganglion means a swelling on
the nerve.
 Caused by a collection of nerve cell
bodies on a peripheral nerve
 A nucleus is an aggregation of cell bodies
in the CNS
 Exception: basal ganglia of the brain
 Ganglia are peripheral; nuclei are central

19. CRANIAL NERVE NUCLEI
 A nucleus is a collection in the central grey
matter of cell bodies of neurons serving
similar functions
 Motor and sensory nuclei
 In the developing neural tube, motor
components are in the ventral portion
(basal lamina) and sensory components in
the dorsal portion (alar lamina)
 separated by the sulcus limitans

20.  Visceral elements develop near the
sulcus
 Somatic elements towards the dorsal
and ventral margins
 Ventral to dorsal arrangement:
Somatic motor, visceral motor, visceral
sensory and somatic sensory.

22.  In the brain stem:
 dorsal aspects of the brain stem were
forcibly parted by the enlarging central
canal which becomes the fourth
ventricle.
 The sequence of somatic motor, visceral
motor, visceral sensory, somatic sensory
is medial to lateral