Cranial Nerve Pathways

Question 1

Describe CNI pathway

Answer 1

Olfactory nerve
Olfactory bulb
Olfactory tracts

Question 2

Describe CNII pathway

Answer 2

Optic nerve
Chiasm
Optic tracts
Lateral geniculate of thalamus
Radiations (inferior radiation is called Meyer's loop)
Occipital cortex

Question 3

Name the sensory cranial nerves

Answer 3

I, II, VIII,

Question 4

Describe CNVIII (cochlear portion) pathway

Answer 4

Spiral ganglion cells to dorsal + ventral cochlear nueclei
Cochlear nuclei to bilateral superior olivary nuclei for timings
S. olivary nuclei to inferior colliculus via lateral lemniscus
Inferior colliculi to medial geniculate of thalamus then auditory cortex

Question 5

Describe CNVIII (vestibular portion) pathway

Answer 5

Vestibular ganglion to vestibular nucleus

Then either thalamus or spinal cord or cerebellum or medial longitudinal nucleus to link to eyes

Question 6

What part of brainstem (if applicable) are each sensory nerve found

Answer 6

I = olfactory mucosa
II = retina then optic canal
VIII = pontomedullary junction

Question 7

Name the motor cranial nerves

Answer 7

III, IV, VI, XI, XII

Question 8

Describe CNIII pathway

Answer 8

Somatic motor to eye muscles = occulomotor nucleus
Parasympathetic to dilator papillae = from pre-tectal nucleus to Edinger-Westphal nucleus then synapse at ciliary ganglion and to dilate pupil

Question 9

Describe CNIV pathway

Answer 9

Trochlear nucleus is found in midbrain

Loops back and crosses before exiting posterior to supply SO of eye

Question 10

Describe CNVI pathway

Answer 10

Abducens nucleus is found posterior pontomedullary junction and at anterior wall of 4th ventricle
Supplies LR of eye

Question 11

Describe CNXI pathway

Answer 11

Anterior roots (remember only motor) of C1-5 ascend to form spinal root
Cranial root comes from nucleus ambiguus and joins spinal root
Immediately goes back out and down the jugular foramen to supply sternocleidomastoid and trapezius

Question 12

Describe CNXII pathway

Answer 12

Hypoglossal nucleus in medulla then through hypoglossal canal to supply muscles of tongue (except palatoglossus)

Question 13

Name the mixed cranial nerves

Answer 13

V, VII, IX, X

Question 14

Modality of the parts of CNV

Answer 14

V1 and V2 are sensory

V3 is sensory and motor

Question 15

Sensory and motor of CNV

Answer 15

Somatosensory for face and chewing proprioception

Motor innervation for muscles of mastication and tensor veil palatine (V3 only)

Question 16

Nuclei for CNV

Answer 16

Sensory:
Proprioception = mesencephalic nucleus
Temperature and pain = spinal nucleus
Vibration = Principle/pontine trigeminal nucleus

Motor:
Motor nucleus

Question 17

Modalities of CNVII

Answer 17

Sensory for taste to anterior 2/3 tongue
Parasympathetics to all glands of face except parotid (pterygopalatine and submandibular ganglia)
Motor to muscles of facial expression

Question 18

Nuclei for CNVII

Answer 18

Sensory (taste) = solitary nucleus
Parasympathetics = superior salivatory nucleus
Motor = Facial motor nucleus

Question 19

Modalities of CNIX

Answer 19

Sensory to throat and eustation tube AND taste and sensation to posterior tongue
Parasympathetics to parotid gland via otic ganglion
Motor to stylopharyngeus

Question 20

Nulei for CNIX

Answer 20

Sensory = spinal trigeminal nucleus
Taste = solitary nucleus
Parasympathetics = inferior salivatory nucleus
motor = nucleus ambiguus

Question 21

Modalities of CNX

Answer 21

Sensory from pharynx to abdomen
Parasympathetics to thoracic and abdominal ganglia
Motor to pharynx and larynx

Question 22

Nuclei for CNX

Answer 22

Sensory = solitary nucleus and spinal trigeminal 
Parasympathetics = dorsal nucleus of vagus
Motor = nucleus ambiguus