ALL CRANIAL NERVES COURSE AND CLINICAL IMPLICATION IN ORAL AND MAXILLOFACIAL SURGERY

1. Nerve supply of head and
neck
Presenter- Dr.shruthi sykam

2. contents
 Introduction
 Embryology of Cranial nerves
 Olfactory
 Optic
 Occulomotor
 Trochlear
 Trigeminal
 Abducent
 Facial
 Vestibulocochlear
 Glossopharyngeal
 Vagus nerve
 Accessory nerve
 Hypoglossal
 Ansa cervicalis
 Cervical plexus
 Summary
 Conclusion
 references

3. Introduction
 There are 12 cranial nerves each
has a number and name as follows.
1. Olfactory.
2. Optic.
3. Oculomotor.
4. Trochlear.
5. Trigeminal.
6. Abducent.
7. Facial.
8. Vestibulocochlear.
9. Glossopharyngeal .
10. Vagus.
11. Accessory.
12. Hypoglossal.

4. embryology
 The development of cranial nerves
starts as early as 4th week of
gestation period
 In the beginning of 4th week cranial
nerve 3,5,7,8,9,10,11 and 12 develop
 Followed by the formation of rest of
the cranial nerves.

5. Attachment of cranial nerves to brain stem
Pons
cerebellum
Middle cerebellar
peduncle

6. Sensory and motor nerves
 PURELY SENSORY – 1 , 2 , 8
 PURELY MOTOR - 3 , 4 , 6 , 12
 MIXED(SENSORY AND MOTOR)- 5 , 7 , 9 , 10,11

7. Cranial nerve :1 – olfactory
 Origin - forebrain.
 Supply- olfactory epithelium.
 Function- smell.
 Exit- cribriform plate
of ethmoid bone.

8. Course and relation
 Olfactory neurons are a bunch of
nerve fibers around 20 in number
 They represent central process of
olfactory cells(16-20 million cells)
 They doesn’t have a nuclei
 The fibers reach the cerebral cortex
without synapsisng in any thalamic
nuclei.

9. Surgical consideration
Damaged in cases of:
 In head injury and frontal bone
fractures due to tearing away of
olfactory bulb as cribrifrorm plate of
ethmoid is fractured
 Frontal lobe tumors.
 Surgical repair can lead to anosmia.
 Properties: Nerve can regenerate.

10. Cranial nerve: 2 - optic nerve
 Origin- forebrain
 Associated nucleus - lateral
geniculate nucleus and pre-tectal
nucleus
 Supply- retina
 Exit- optic canal

11. CONTENTS OF OPTIC CANAL
 OPTIC NERVE: It’s a group of axons
of ganglion cells of retina.
 OPTIC CHIASMA:consists of nasal
fibers and temporal fibers.
 OPTIC TRACT: it contains temporal
fibers of same side and nasal fibers of
the opposite side
 VISUAL CORTEX: where color,
size,shape,motion ,illumination,and
transperancy are appreciated.
 No ability to regenerate

12. VISUAL FEILD
 It consists of temporal field of the
vision and nasal field of vision
 Visual field is also upper field and
lower visual fields so there are 4
fields of vision
 Upper temporal
 Lower temporal
 Upper nasal
 Lower nasal

13. Reflexes:
1. Pupillary reflex.
2. Accomodation reflex.
3. Dilation of pupil.
4. corneal/conjunctival reflex.
5. Visual body reflex.

14. CLINICAL CONSIDERATION
 Loss of vision in one half of visual
field is heminopia
 If defect is in same side it is called
homonymous and heteronymous if
defect is in opposite side
 Papilloedema:results due to increase
in intra cranial pressure
 Optic nerve damage results in
complete blindness of that eye

16. Cranial nerve:3- oculomotor
 Origin: mid brain
 Supplies:
 Four intraocular muscle
 One extraocular muscle
 proprioceptive to above muscle
 parasympathetic to pupils
 Nuclei - oculomotor nucleus and
Edinger Westphal nucleus.

17. Course and relation
 Attached to oculomotor sulcus at
base of the brain
 Passes between superior and
posterior cerebellar artery on the
lateral side and reach cavernous sinus
 On the later wall of sinus divides into
upper and lower divisions
 And exists from superior orbital
fissure
 The smaller upper divison supplies
superior rectus and part of levator
palpabre superiors
 The large lower divison supplies
1. Medial rectus
2. Inferior rectus
3. Inferior oblique

18. Clinical consideration
 Complete or total paralysis in 3rd nerve leads
to:
1. Ptosis; drooping of upper eyelid-paralysis
of voluntary part of levator palpebrae
superioris
2. Lateral squint- unopposed action of lateral
rectus and superior oblique
3. Dilatation of pupil-paralysis of
parasympathetic fibers
4. Loss of accommodation-paralysis of ciliary
muscle
5. Slight proptosis-unopposed action of
lateral rectus and superior oblique
6. diplopia

19. Cranial nerve:4- trochlear nerve
 Origin: only cranial nerve which arise
from dorsal part of brain
 Function :Supplies superior oblique
muscle
 Nucleus : situated in ventromedial
part of central grey matter at
midbrain
 Exit: superior orbital fissure
 Damage causes diplopia when
looking downwards

20. Course and relation
 The nerve winds around superior
cerebellar peduncle above the pons
 Passes between posterior and
superior cerebellar artery
 Enters cavernous sinus by piercing its
roof
 Lies between oculomotor and
ophthalmic nerves
 It is the longest cranial nerve

21. Clinical consideration
 When damaged results in diplopia on
looking downward
 Paralysis of this nerve results in
1. Defective depression of adducted
eye
2. diplopia

22. Cranial nerve:5- trigeminal
 Origin: arise from lateral part of upper pons
 Largest intra cranial course
 Nuclear columns:
1. General somatic afferent column:
 Spinal nucleus of 5th nerve:fibers convey pain
and temperature from face and relay in it
 Superior sensory nucleus:carry touch and
pressure
 Mesencephalic nucleus: proprioceptive
impulses from muscles of
mastication,TMJ,teeth.
2. Branchial efferent column:supply eight
muscles derived from 1st branchial arch

23.  The cell bodies lie in the V
ganglion/semilunar
ganglion/gasserian ganglion.
 Which lies in the petrous part of the
temporal bone in dural cave,the
meckel’ cave.
 Supply 4 mucles of mastication and 4
other muscles-tensor veli
palatini,tensor tympani,mylohyoid
and anterior belly of digastric.

24. branches
 Comprises of 3 branches
1. Ophthalmic V1(sensory)
2. Maxillary V2(sensory)
3. Mandibular V3(mixed)

25. Clinical consideration
 In injury to:
1. Opthalmic nerve: loss of corneal
blink reflex
2. Maxillary nerve:loss of sneeze reflex
3. Mandibular nerve: loss of jaw jerk
reflex
 Trigeminal ganglion harbours herpes
zoaster virus causing shingles
 Hypoacusis: partial deafness to low
pitched sounds due to paralysis of
tensor tympani muscle.

26. Surgical considerations
Lingual nerve is very close to mandibular 3rd molar
Risk of IAN injury during orthognathic surgery
Abnormal communication between mylohyoid nerve and lingual
nerve can delay local anesthetic action
Infraorbital nerve usually injured in infraorbital fracture.
Risk of injury to nerve medial to mandibular condyle during gap
arthroplasty.

27. Oculo cardiac reflex
 Also called as trigemino cardiac reflex
 When there is pressure on eye ball
due to trauma, hematoma
 The signals travel through ciliary
muscles to gasserian ganglion
 Then to nucleus of trigeminal and
vagus nerve
 Resulting in increase in
parasymphathetic tone and
bradychardia in reflex

28. Arterial compression of nerve is the chief cause of trigeminal
neuralgia: neurolSci;(2014)
Trigeminal neuralgia:
Characterized by attacks of severe pain in area of
distribution of maxillary and mandibular divisions.

29. Cranial nerve 6: abducent
 Origin: upper part of floor of 4th
ventricle in lower pons
 Nucleus: lies in pons closely related
to medial longitudinal bundle.
 Exist: medial part of superior orbital
fissure.
 Function: supplies lateral rectus
muscle

30. Course and distribution
 Nerve runs ventrally and downwards
and is attached to lower border of
pons
 It runs anterior to the cerebellar
artery
 Enters cavernous sinus by piercing
the posterior wall
 Lies lateral to ICA in the cavernous
sinus
 In orbit it ends by supplying lateral
rectus muscle

31. Clinical consideration
 Nerve paralysis results in failure of
abduction of the affected eye
 Diplopia occurs due to paralysis of
right lacteral rectus muscle

32. Cranial nerve 7:facial nerve
 Queen of the face
 Origin: lateral border of lower part of
pons
 Nucleus:
1. Motor nucleus
2. Superior salivatory nucleus
3. Lacrimatory nucleus
4. Nucleus of tractus solitarius

33. Course and relation
1. Within the facial canal:
 Greater petrosal nerve
 The nerve to stapedius
 Chorda tympani
2.At its exit from stylomastoid foramen:
 Posterior auricular
 Digastric
 stylohyoid
 3. terminal branches within the
parotid:
 Temporal
 Zygomatic
 Buccal
 Marginal mandibular
 cervical

34.  Ganglia associated:
 Geniculate ganglion:Located at the
first bend of facial nerve.
 Submandibular ganglion:
parasympathetic ganglion for relay of
scretomotor fibers to submandibular
and sublingual glands.
 Pterygopalatine ganglion: the fibers
reach from nerve to pterygoid canal.

35. variations
 In 22% cases the zygomatic and
buccal branch anastomose in their
path
 In 21% 2 branches of the temporal
region are seen

36. Clinical consideration
 BELLS PALSY
 Infranuclear lesion of facial nerve
 Ipsilateral paralysis of facial muscles
 supra nuclear lesion causes-
contralateral paralysis of lower part
of face

37.  “crocodile tear syndrome”
(lacrimation while eating)
 A unilateral lesion causing damage
of the facial nerve proximal to the
geniculate ganglion,regenerating
fibers for submandibular salivary
gland grow in endoneural sheath of
preganglionic secretomotor fibers
supplying lacrimal glands
 Freys syndrome:
•occurs due to injury to
auriculotemporal nerve
•which regenerates to attach
to sweat glands
•instead of parotid gland

38. Ramsay hunt syndrome
 Involvement of geniculate ganglia by
herpes zoaster causing
 Hyperacusis
 Loss of lacrimation
 Loss of sensation in anterior 2/3rd of
tongue
 Bells palsy and lack of salivation
 Vesicles on the auricle

39. Cranial nerve 8- vestibulocochlear
 Origin: lateral bored of lower pons
 Nuclei: ventricular ganglion
 Exist: auditory canal
 Fuction: hearing

40. Pathway of hearing:

41. Clinical consideration
 Deafness :
1. Conductive loss-failure of sound waves to reach cochlea
2. Sensorineural deafness-production of transmission of action potential due to
cochlear disease
3. Cortical deafness-failure to understand the spoken language
 Vertigo-illusion of rotary movements due to disturbed orientation of body in space
 Tinnitus-ringing sensation in ear
 Meniere’s syndrome-recurrent attacks fo tinnitus,vertigo,hearing loss

42. Cranial nerve 9- glossopharyngeal nerve
 Nerve of the 3rd branchial arch
 Origin: lower part of pons
 Nuclei:
1. Nucleus ambigus
2. Inferior salivatory nucleus
3. Nucleus of tractus solitarius
 Function: taste
 Exist: jugular foramen

43. Course and branches
 Branches:
1. Tympanic nerve
2. Carotid branch
3. Pharngeal branches
4. Muscular branch
5. Tonsillar branch
6. Lingual branch

44. Clinical consideration
 Lesion of nerve causes
1. Absence of secretion from parotid
gland
2. Absence of taste from posterior
2/3rd of the tongue
3. Loss of pain in
tongue,tonsil,pharynx and soft
palate
 Glossopharyngeal neuralgia:
Short,sharp attack of pain affecting
posterior part of pharynx
 Pharyngitis may be a refered pain in
the ear as both are supplied by the
same nerve.

45. Cranial nerve 10- vagus
 ‘Vague’- due to extensive course
 Nuclei :
 Nucleus ambigus
 Dorsal nuclei of vagus
 Nucleus of tractus solitarius
 Nucleus of spinal tract of trigeminal
 Exist: jugular foramen

46. Branches
1. Meningeal branch
2. Auricular branch
3. Pharyngeal
4. Carotid
5. Superior laryngeal
6. Recurrent laryngeal
7. cardiac

47. Clinical considerations
 Paralysis produce:
1. Nasal regurgitation
2. Nasal twang of voice
3. Hoarsness of voice
4. Flattening of palatal arch
5. Cadaveric position of vocal chords
6. dysphagia

48. Cranial nerve 11- accessory
 Origin -Has 2 roots
1. Cranial root- arise from lower part
of nucleus ambigus
2. Spinal root-arise from long spinal
nucleus of spinal cord

49. Course and distribution
 Arises from from 5 segments of
spinal cord
 Closely related to internal jugular
veins and ICA
 Enters posterior triangle of neck by
piercing through the
sternocledomastoid muscle

50. Clinical consideration
 Lesion of spinal root causes drooping
of shoulder and inability to turn chin
to opposite side which is called as
whiplash injury
 Nerve damage usually occurs during
neck dissections.
 Irritation of nerve cause torticollis or
wry neck
 Supranuclear connections act on
ipsilateral sterno cledomastoid and
on contralateral trapezius

51. Neurotization of the phrenic nerve with accessory nerve for high cervical spinal cord injury with respiratory distress: an
anatomic study.
AIM:
High cervical spinal cord injury is associated with high morbidity and mortality. Traditional treatments carry various
complications such as infection, pacemaker failure and undesirable movement The purpose of the study is to provide
anatomic details on the accessory nerve and phrenic nerve for neurotization in patients with high spinal cord injuries
CONCLUSION:
The accessory nerve and the phrenic were similar in width, thickness and the number of motor nerve fibers. And the lengths of
accessory nerve were long enough for neuritisation with phrenic nerve.
Turk neurosur july 2014: Wang, Zang, Nicholas

52. Cranial nerve 12- hypoglossal
 Origin- hypoglossal nuclei of medulla
 Nucleus:
Lies in the 4th ventricle beneath the
hypoglossal triangle
Function : supplies extrinsic(
genioglossus, hyoglossus,styloglossus
and palate glossus)and intrinsic(superior
and inferior longitudinal muscles, vertical
muscle and transverse) muscles of the
tongue

53. Clinical considerations
 Infranuclear lesion produce paralysis
of tongue on that side with wasting
of muscles
 Supranuclear lesion causes paralysis
without muscle wasting

54. HYPOGLOSSAL-FACIAL-JUMP-ANASTOMOSIS WITHOUT AN INTERPOSITION
NERVE GRAFT.
 OBJECTIVES/HYPOTHESIS:
 The hypoglossal-facial-anastomosis is the most often applied procedure for the reanimation of a long lasting
peripheral facial nerve paralysis. We describe the modified technique of the hypoglossal-facial-jump-
anastomosis without an interposition and present the first results.
 RESULTS:
 The reconstruction technique succeeded in all patients: The facial function improved within the
average time period of 10 months to the House-Brackmann score 3.
 CONCLUSION:
 This modified technique of the hypoglossal-facial reanimation is a valid method with good clinical
results, especially in cases of a preserved intramastoidal facial nerve.
Laryngoscope. 2013 Oct : BUETNER, LUERS

56. Cranial nerve 13??
 Known as cranial nerve zero or
terminal nerve
 It is a microscopic plexus of
unmyelinated peripheral nerve
fascicles
 Projects from nasal cavity enters
brain just a bit head of other cranial
nerves

57. conclusion
 Head and neck consists of twelve cranial nerves which supply many closely associated structures
. These structures form the social picture of an individual .
 Hence a proper understanding of the course of nerves of the facial planes and their relations
with their associated central nuclei is must for a maxillofacial surgeon to satisfactorily manage
any injury or pathology in the region

58. References
 GRAY’S ANATOMY: 40TH EDITION
 SURGICAL ANATOMY OF FACE: by Wayne F
 COLOUR ATLAS OF ANTOMY : BY ROHEN
 GRANT’S ATLAS OF ANATOMY : 12TH EDITION
 HUMAN ANTOMY: B D CHAURASIA VOL-3
 PRINCIPLES OF ANATOMY AND PHYSIOLOGY
GERARD TORTORA
 REVIEW OF FACIAL NERVE ANTOMY: TERENCE SUSAN

59. Thankyou

60. “
”
Cranial nerve examination and
applied aspect
Dr. Srishti ghorpade