Cranial Nerves

Question 1

CI

Answer 1

Olfactory:

• special sensory - smell
• enters outside brainstem
• leaves via forebrain
• synapses in olfactory bulb

Question 2

CII

Answer 2

Optic

• special sensory - vision
• partial decussation at optic chiasm

Question 3

CIII

Answer 3

Oculomotor

• 4 x extra ocular muscles of eye
• and parasympathetic to constrict iris and cilary bodies (Edinger-Westphal).

Question 4

CIV

Answer 4

Trochlear

• exits brain stem dorsally behind pons after decussating
• superior obliques (down and out)

Question 5

CV

Answer 5

Trigeminal

• somatosensory for head and neck
• 3 branches - mandibular, maxillary and opthalmic
• pain and temp to the spinal nuclei located in the medulla
• touch and pressure to the principal nucleus in the midbrain
• proprioception to the mesenphalic nuclei (jaw reflexes aswell)
• motor; muscles of masticaiton

Question 6

CVI

Answer 6

Abducens

• junction between pyramids and pons
• innervates lactus rectus which abducts the eyeball away from the midline

Question 7

CVII

Answer 7

Facial

• at cerebellar pontine angle
• motor; muscles (facial expression)
• sensory; skin of external ear canal and eardrum
• special sensory; taste (ant 2/3rds tongue)
• parasympathetic; salivary gland innervation (not parotid) and lacrimal gland (keeps cornea moist)

motor neurones to upper face = bilateral
motor neurones to lower face = contralateral unilateral

UMN lesion - lower face paralysis = central facial palsy
LMN lesion - entire face affected on one side = peripheral face/bell’s palsy

Question 8

CVIII

Answer 8

Vestibulocochlear

• vestibular branch - balance, posture, movement
• cochlear branch - hearing

Question 9

CIX

Answer 9

Glossopharyngeal

• special sensory; taste (post 1/3rds of tongue)
• visceral sensory; carotid body (blood pco2)
• motor; upper pharynx
• parasympathetic; parotid gland

Question 10

CX

Answer 10

Vagus

• sensory
  a) somatosensory - mucous membranes of laryngopahrynx, larynx and upper trachea
  b) visceral - trachea, lungs, carotid sinus, guts
• motor
  a) somatic; lower pharynx, upper oesophagus (swallowing and vomitting)
  b) parasympathetic - cardiac muscle (heart beat), smooth muscle of GIT, tachea and bronchi (airway diameter)

wanders into abdomen and thorax

Question 11

CXI

Answer 11

Spinal Accessory

• muscles involved in shoulder and head movements
• sternocleiodmastoid
• trapezius

Question 12

CXII

Answer 12

Hypoglossal

• between olive and pyramids
• intrinsic and most extrinsic muscles of the tongue