3,4,6 CRANIAL NERVES

1. CRANIAL NERVES
Dr. Anoop R Prasad

2. 3, 4 and 6th cranial nerves
• For muscles of eye movements
• CN 6 (Abducens) - Lateral rectus muscle
– moves eye laterally
• CN 4 (Trochlear) -Superior oblique muscle - moves eye
down (depression) when looking towards nose; also
rotates internally.
• CN 3 (Oculomotor) All other muscles eye movement –
also raises lid & mediates pupillary constriction.

8. EXAMINATION
• Observe for Lagging and Nystagmus
• Exophthalmus , enophthalmus
• Squint

10. EXAMINATION
• Patient doesn’t move head, following your
finger w/their eyes as you trace out letter “H”
• Alternatively, direct them to follow finger w/their eyes as
you trace large rectangle
• Eyes should move in all directions, in
coordinated, symmetric fashion.

12. PUPILS
• Size :
• normal – 2 – 6 mm
• miosis - <2mm
• Mydriasis - >6mm
• Shape
• Equality :
• >2 mm difference is significant

13. • Pupillary reflex :

14. • Sit in front of the patient & have him look straight
• Bridge the patient’s nose with your left hand
• Shine a light into one eye: optic nerve is afferent
• Note pupillary constriction in that eye: direct reflex
• Also note constriction in opposite eye:
indirect/consensual

15. • Accommodation reflex:
• Convergence
• Miosis
• Increase in anterior curvature of lens

20. SEVENTH NERVE

22. EXAMINATION
• Taste sensation from anterior 2/3 tongue – sweet, sour,
bitter, salty
• Facial asymmetry
• Prominence of Nasolabial fold
• Forehead wrinkles
• Ask to close eyes
• Ask to show the teeth
• Cheek puffing
• Bell’s Phenomenon

24. Testing the motor function of the facial nerves. Ask the
patient to (A) raise the eyebrows, (B) show the teeth, (C) close
the eyes against resistance and (D) blow out the cheeks.

26. 9 & 10

27. EXAMINATION
• Examined together
• Character of voice
• Nasal regurgitation
• Dysphagia
• Look for position of palate & uvula at rest and ask the
patient to say ‘Aaah’
• Gag reflex elicited by touching the pharynx/palate
• Afferent limb- 9th cranial nerve
• Efferent limb- 9/10th cranial nerve
• Elevation of uvula and mid line raphe of palate
• Unilateral weakness- deviation towards normal side
• Bilateral cerebral lesion- hyperactive gag reflex

28. • Patient is unable to pronounce words that require
complete closure of naso pharynx
• Egg-Eng
• Recurrent laryngeal nerve palsy causes dysphagia &
bovine cough

29. Spinal Accessory nerve
• Cranial root and spinal root(C2 – C5)

30. • Acting alone- SCM turns Head to opposite side
• Acting together- Flex the neck and bring the head
forward
• Trapezius- both contract- Head drawn backwards face
deviate upwards.
Helps in abduction beyond 900

31. EXAMINATION
• SCM- compare both sides by asking the patient to turn
the head against resistance
• Ask the patient to flex his neck with examiner exerts
pressure on the forehead
• Trapezius- ask to raise shoulders towards ears
• Try to depress shoulders forcibly

32. • In bilateral SCM weakness- Head seems to be left
behind when the patient sits up
• In unilateral weakness- patient will not be able to turn his
head against resistance to opposite side
• Trapezius weakness- shoulder drooping
• Shrugging of shoulder can be weaker

33. HYPOGLOSSAL NERVE

34. • Supplies all intrinsic and extrinsic muscles except
palatoglossus
• EXAMINATION
• With tongue inside mouth look for size/wasting
fasciculation/ Involuntary movements.
• Ask to protrude- look for deviation
• Assess power by asking to press against the
cheek/move from side to side

35. SUMMARY
I Sense of smell
II Visual acuity, visual field, Pupil and fundi
III,IV,VI Eye movements, accommodation and Nystagmus
V Facial sensations, masseters, corneal and jaw reflex
VII Muscles of facial expressions & Taste ant. 2/3 tongue
VIII Rinne’s,Weber’s and Vestibular test
IX Pharyngeal sensation
X Palate movements and Gag reflex
XI Trapezius and Sternocleidomastoid
XII Tongue appearance and movements