2. SURGICAL ANATOMY
OF
CRANIAL NERVES
GUIDED BY
DR.RAMAKRISHNA
DR.VIVEK
PRESENTED BY:
DR.MURARI WASHANI
I YEAR M.D.S

3. CONTENT
 INTRODUCTION
 CRANIAL
NERVES
 CLINICAL
TESTING OF NERVES

4. INTRODUCTION
 An
example mnemonic sentence for the initial
letters "OOOTTAFVGVAH" is "Oh, oh, oh, to touch
and feel very good velvet...ah,

7. OLFACTORY
NERVE

8.  The
olfactory nerve transmits olfactory impulses
from the olfactory epithelium of the nose to the
brain
 It is actually a collection of sensory nerve rootlets
that extend down from the olfactory bulb and
pass through the many openings of the cribriform
plate in the ethmoid bone.

11.  Clinical
notes
 Anosmia
 CSF
( loss of sense of smell)
Rhinnorhoea
 Hyposmia
 Parosmia
(a decreased sense of smell)
(a perversion of the sense of smell)
 Cacosmia
(awareness of a disagreeable or
offensive odour that does not exist)

12. Test: Bedside
testing with pure (non-irritant) odours
should be performed during early recovery
 Serial
testing should be done in patients with
anosmia : should try ammonia
 MRI
imaging frequently reveals abnormalities in the
olfactory bulbs and tracts and in the inferior frontal
lobes in patients with posttraumatic olfactory
dysfunction

13. OPTIC NERVE

14. 
Sight is dependent not only on cerebral cortex but also on
other six cranial nerve.

Occulomotor ,trochlear nerve and abducent nerve
innervate the extrinsic occular muscle and control
movement of eye ball.

Pain, touch and pressure sensation is carried by the
opthalmic nerve.

Facial nerve innervate the orbicularis oculi muscle.

17. CLINICAL NOTES: Section
of one optic nerve causes blindness in one
eye
 Bitemporal hemianopia
 Homonymous hemianopia
 Exudates, haemorrhages and abnormalities of
blood vessels may be seen on retinoscopy and
may be signs of generalized disease processes
(e.g. diabetes, rheumatoid arthritis, etc.)
 Damage to optic nerve can cause diplopia,
blurring of vision

18. Clinical testing
 Confrontation
 Snellens
 Colour
test –
test-
vision is tested using Ishihara plates which
identify patients who are colour blind.

19. Occulomotor

20. INTRODUCTION
 Occulomotor
nerve supplies
 the levator palpebral superioris ,
 Superior rectus,
 medial rectus,
 inferior rectus and
 inferior oblique

22. CLINICAL NOTES: Occulomotor nerve injury
 Ptosis-
paralysis of levator palpabre
 lateral
squint
 spasm
of the muscles supplied by it (e.g. spasm of
medial rectus leading to a medial squint.

23. TROCHLEAR
NERVE

24.  Trochlear
nerve supplies the superior oblique.
 It is the smallest nerve in terms of the number of
axons it contains. It has the greatest intracranial
length
o trochlear nerve is so called because superior oblique
(which it supplies) is arranged as a pulley (Latin:
trochlea – pulley).

25. Clinical notes
.limiting infero-lateral moment of eye
Injury to the trochlear nerve can cause vertical diplopia on looking
downward which improves with contralateral head tilt and worsens
with ipsilateral head tilt.

26. Trigeminal
nerve

27.  Originate
 largest
cranial nerve
 contains
 The
from trigeminal ganglion.
both sensory & the motor fibres
word trigeminal is derived from the word
‘trigemina’ meaning triplet

28. DIVISIONS OF TRIGEMINAL NERVE:
1. Ophthalmic nerve
2. maxillary nerve
3. mandibular nerve

29. OPTHALMIC BRANCH:
transmits sensory fibres from
 the eyeball,
 the skin of the upper face and anterior scalp,
 the lining of the upper part of the nasal cavity
and air cells,
 and the meninges of the anterior cranial fossa.

33.  Clinical
notes
1.Corneal reflex
2.Supraorbital injuries
3.Ethmoid tumours
4.Nasal fractures

34. MAXILLARY NERVE
 The
maxillary nerve transmits sensory fibres from the
skin of the face between the palpebral fissure and
the mouth, from the nasal cavity and sinuses, and
from the maxillary teeth.
The maxillary division gives off branches in four
division :
 In the middle cranial fossa
 In the ptreygopalatine fossa
 In the infra-orbital groove and canal
 On the face ( Terminal branches )

35. 

Branches in the middle cranial fossa : middle meningeal nerve.
Branches in pterygopalatine fossa : 1. Zygomatic nerve
a.Zygomaticofacial nerve
b.Zygomaticotemporal nr
2. Pterygopalatine nerve
a.Orbital nerve
b.Nasal nerve
- Posterior superior lateral
nasal branch .
- Medial or septal branch.
c.Palatine nerve
Posterior superior alveolar branches :
 Branches in the infraorbital groove and canal :
- Middle superior alveolar nerve.
- Anterior superior alveolar nerve.
 Terminal branches
- Inferior palpebral branches
- Lateral nasal branches
- Superior labial branches


38.  Clinical
notes
1 Infraorbital injuries: malar fractures
2 Maxillary sinus infections
3 Maxillary antrum tumours
4 Maxillary teeth abscesses
Clinical testing
Test skin sensation of lower eyelid, cheek and upper
lip

39. MANDIBULAR BRANCH
 The
mandibular nerve is a mixed sensory and
motor nerve.
 It
transmits sensory fibres from the skin over the
mandible , side of the cheek and temple, the oral
cavity and contents, the external ear, the
tympanic membrane and temporomandibular
joint.
 It
is the largest of all the three divisions.

42.  Clinical
notes
1 Lingual nerve damage
2 Inferior alveolar nerve and inferior alveolar nerve
block
3. TRIGEMINAL NEURALGIA:Clinical testing
1 Sensory:
Test skin sensation of chin and lower lip.
2 Motor:
Feel contractions of masseter, temporalis. Open jaw
against resistance (pterygoids, mylohyoid, anterior
digastric)

43. ABDUCENT
NERVE

44. Supplies lateral rectus muscle.
Note: the abducent nerve is so called because
lateral rectus abducts the eyeball.

 The
abducent nerve innervates lateral rectus
muscles exclusively.
 It emerges from the brain stem between the pons
and the medulla oblongata and usually runs
through the inferior venous compartment of the
petroclival venous confluence in a bow shaped
canal, Dorello’s canal.

47. DAMAGE TO THE ABDUCENS NERVE :
 - In a complete injury of the abducent nerve, the
affected eye is turned medially. In an incomplete
injury, the affected eye is seen at midline at rest,
but the patient cannot deviate the eye laterally.
 -Combined
injuries of the III, IV and/or V nerves are
common and can result in the loss of depth
perception and reading and visual scanning
problems

48. FACIAL NERVE

49.  The
facial nerve supplies the muscles of facial
expression.
 taste sensation from the anterior portion of the
tongue and oral cavity.
 It is a mixed type of nerve, contains both sensory &
motor fibres

51.  Course
and branches
 Intracranial course and branches

52.  Extracranial
course and branches

53. 

The most important thing about the intracranial course
of VII is its relationship to the middle ear.
The most important thing about the extracranial
course is its relationship to the parotid gland.
Clinical notes
1.
Parotid disease
2.
Stapedius: hyperacusis (cannot tolerate sound)
3.
Bell’s palsy
4.
Facial nerve injury in babies- mastoid rudimentry

54. Clinical testing
1. Observe the face. Normal facial movements (lips,
eyelids, emotions) and the presence of normal
facial skin creases indicate an intact nerve.
2. Test strength by trying to force apart tightly closed
eyelids. This should be difficult.

55. VESTIBULOCOCHLEAR
NERVE:-

56.  The
vestibulocochlear nerve is the sensory nerve
for hearing (cochlear) and equilibration
(vestibular).
 It is also known as the statoacoustic nerve.
Origin and course
 Arises laterally in cerebellopontine angle. Passes
with facial nerve into internal acoustic meatus
(temporal bone). Cochlear portion (anteriorly)
and vestibular portion (posteriorly).
Vestibulocochlear nerve does not emerge
externally.

58. TWO PARTS
A.COCHLEAR NERVE:- CONCERNED WITH HEARING
2.VESTIBULAR NERVE:-CONCERNED WITH BALANCING
CLINICAL NOTES
1.Lesions- Hearing defects
2.TRAUMA
- IN FRACTURE OF MIDDLE FOSSA
- COMPRESSED BY TUMOUR
Tests Rinne’s
 Weber’s

59. GLOSSOPHARYNGEAL
NERVE

60. The main function of the glossopharyngeal nerve is the sensory supply
of the oropharynx and posterior part of the tongue.

61.  BRANCHES
 The
glossopharyngeal nerve has following
branches:
i) Tympanic
ii) Carotid
iii) Pharyngeal
iv) Muscular
v) Tonsillar
vi) Lingual

63. Clinical notes: Glossopharyngeal neuralgia
 Swallowing
difficulties
 Tardive
dyskinesia: tardive dyskinesia is
characterized by repetitive, involuntary,
purposeless movements
Testing of nerve
 Tickling the posterior wall of pharynx
 Taste sensibility on the posterior 1/3rd of tongue

64. VAGUS NERVE

65.  The
main functions of the vagus are phonation
and swallowing. It also transmits cutaneous
sensory fibres from the posterior part Of the
external auditory meatus and the tympanic
membrane.
 It is so called because of its extensive( vague)
course through the head, neck & thorax
 The vagus is the most extensively distributed of all
cranial nerves. Its name reflects both its wide
distribution and the type of sensation it conveys
(Latin: vagus – vague, indefinite, wandering)

69. 
Clinical notes

1.
Palatal elevation – ‘ah’ glossopharyngeal and vagus nerves.

2.
Vagal reflexes: coughing, vomiting, fainting

3.
Referred pain

4.
Vocal cords

Clinical testing
If speech is normal, the vagus nerves are fine. Tradition and
convention, however, often demand the charade of testing them.
1 Listen to speech.
2 Gag reflex
3 Testing palatal, pharyngeal movements, and listening to speech are
tests of motor components of IX, X and cranial XI .They are thus tests of
the nucleus ambiguss.


70. ACCESSORY
NERVE

71. The accessory nerve has two parts: cranial and spinal.
Oddly enough, when clinicians refer to the eleventh cranial
nerve, or accessory nerve, they almost always mean spinal
accessory
 Origin and course of spinal accessory)
• Rootlets from upper four or five segments of spinal cord continue series of rootlets of IX, X and cranial XI.
• Emerge between ventral and dorsal spinal nerve roots, just
behind denticulate ligament.
• Ascends through foramen magnum to enter posterior
cranial fossa.
• Briefly runs with cranial XI before emerging through jugular
foramen (middle compartment).
• Passes deep to sternocleidomastoid which it supplies.
• Enters roof of posterior triangle of neck. Surface marking in
poste-rior triangle: one third of way down posterior border of
sternocleidomastoid to one third of way up anterior border of
trapezius.


74. Clinical notes
•
The accessory nerve is vulnerable in the posterior
triangle as it crosses the roof.
•
Such injuries result in paralysis of trapezius (but not
sternocleidomastoid which it has already supplied) and thus
shoulder abduction beyond 90° involving scapular rotation is
impaired (hair grooming, etc.).
•
The accessory nerve may be damaged in dissection
Of the neck for malignant disease, in biopsy of enlarged
lymph nodes in and around the posterior triangle, or in
penetrating injuries to this region.

Clinical testing of spinal accessory
 1.
Ask the patient to shrug the shoulders (trapezius)
against resistance.
 2.
Ask the patient to put hand on head (trapezius:
shoulder abduction beyond 90°).
 3.
Ask the patient to move the chin towards one shoulder
against resistance (contralateral sternocleidomastoid).

75. HYPOGLOSSAL
NERVE:

76. 

The hypoglossal nerve supplies the muscles of the tongue.
Movements of the tongue are important in chewing, in the
initial stages of swallowing and in speech. It also conveys
fibres from C1 which innervate the strap muscle
Origin, course and branches
•Originates from medulla by vertical series of rootlets between
pyramid and olive.
•Hypoglossal (condylar) canal in occipital bone.
•Receives motor fibres from C1 and descends to
submandibular region.
•Turns forwards, lateral to external carotid artery, hooking
beneath origin of occipital artery. Passes lateral to hyoglossus
and enters tongue from below.
•Gives descendens hypoglossi to ansa cervicalis carrying
fibres from C1 to strap muscles; other C1 fibres remain with XII
to supply geniohyoid.
•Supplies intrinsic muscles of tongue, hyoglossus, genioglossus
and styloglossus.


79. Clinical notes
1. Hypoglossal nerve lesions
•damage to the hypoglossal nerve in the neck would result in an
ipsilateral lower motor neuron lesion. This would cause the
protruded tongue to deviate to the side of the lesion.
2.Carotid artery surgery, block dissection of neck
•The hypoglossal nerve is vulnerable in surgery (e.g. carotid
endarterectomy, block dissection of the neck for malignant
disease) where it passes under the origin of the occipital artery.
Clinical testing
1.Ask the patient to protrude tongue. If it deviates to one side,
then
the nerve of that side is damaged – the tongue is pushed to the
paralysed side by muscles of the functioning side.
2.Ask patient to push tongue into cheek, then palpate cheek to
feel tone and strength of tongue muscles.

80. GRAYS ANATOMY
ATLAS OF HUMAN BODY- NETTERS
LASTS ANATOMY – SINNATANBY
MONHEIMS LOCAL ANESTHESIA AND PAIN
CONTROL – C.RICHARD BENNETT
• Hollinshead's Textbook of Anatomy
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