Pons

Question 1

3 CNs that Come out Pontomedullary Junction (medial lateral)

Answer 1

VI, VII, VIII. Motor->sensory

Question 2

14 Items in Pontomedullary Pons

Answer 2

Corticospinal tract (w/ corticopontine and bulbar fibers)
Vestibular and Cochlear N.s (VIII)
Superior olive
Inferior cerebellar peduncle
Vestibular nuclei
Trigeminothalamic, spinothalamic tracts and medial lemniscus
Ventral and dorsal cochlear nucleus
Spinal tract/nucleus of V
Central tegmental tract
Medial longitudinal fasciculus
Trapezoid body

Question 3

Notable Point About Sensory Fibers in Pons

Answer 3

Medial lemniscus and spinothalamic/trigeminothalamic tracts move close to each other so lesion can knock out all contralateral sensory

Question 4

Corticopontine Fibers

Answer 4

Synapse in pons and cross into cerebellar peduncle

Question 5

Corticobulbar Fibers

Answer 5

CN going to pretty much any CN nucleus (motor)

Question 6

Notable Point About Medial Longitudinal Fasciculus

Answer 6

Stays where it is in middle posterior

Question 7

Trapezoid Body

Answer 7

2nd order neurons for hearing crossing

Question 8

3 Nuclei of Caudal Pons

Answer 8

Facial, abducens, and spinal nucleus of V

Question 9

Notable Point About VI and VII

Answer 9

VI goes straight out from nucleus, but VII goes back and wraps around VI nucleus and then goes out more laterally, so lesion to VI nucleus will also take out VII

Question 10

14 Items in Middle Pons

Answer 10

Corticospinal/pontine/bulbar tracts
Pontocerebellar tract (crossing)
Medial lemniscus
Spinothalamic tract
V
Trigeminothalamic tract
Motor nucleus of V
Mesencephalic nuc of V
Main sensory nuc of V
Locus ceruleus
Medial longitudinal fasciculus
Raphe nucleus

Question 11

Locus ceruleus

Answer 11

Sends NE-ergic neurons throughout brain to kinda oppose Raphe

Question 12

Sensory Path of V

Answer 12

Come in though V branches
Synapse at trigeminal ganglion
Spinal tract of V
Synapse at spinal nucleus of V (along w/ cutaneous from VII, IX, and X)
Decussate and go up trigeminothalamic tract
Synapse in thalamus (3rd order)
Go to postcentral gyrus in cortex

Question 13

Motor Nucleus of V

Answer 13

Corticobulbar fibers (upper motor neurons) come down to innervate/synapse and give off ipsilateral motor neurons to innervation of 8 1st branchial arch muscles

Question 14

Mesencephalic Nucleus

Answer 14

Brings in proprioceptive sensory from jaw, first order cell bodies like DRG but in CNS

Question 15

4/5 Locations Vestibular Nuclei Project To

Answer 15

Spinal cord via vestibulospinal tracts
Eye motor nuclei via MLF
Cerebellum via inferior cerebellar peduncle
Ventral posterior nucleus of the thalamus (& postcentral gyrus of cortex)

Question 16

Notable Aspect About Cochlear Nuclei

Answer 16

Don’t get normal 2nd order decussation. Instead get bilateral projections - ipsi and contralateral. Lesions affect hearing on both sides

Question 17

5 Sensory Tracts Through Pons

Answer 17

Medial lemniscus (gensens)
Spinothalamic tracts (pain/temp)
Lateral lemniscus (auditory)
Spinal tract of V (1st order sensory gen/pain/temp from face)
Trigeminothalamic tracts (2nd order sensory gen/pain/temp from face)

Question 18

Lesion of V

Answer 18

Ipsilateral effects of all 8 muscles, and all sensation from face

Question 19

Lesion of VI

Answer 19

Ipsilateral eye deviates medially (strabismus) and double vision (diplopia)

Question 20

Lesion of VII

Answer 20

Ipsilateral facial muscle paralysis (+stapedius/stylohyoid/post belly digastric)
Lose parasymp to glands besides parotid
Bell’s palsy

Question 21

Acoustic Neuroma

Answer 21

Lesion in internal acoustic meatus, can lose VIII and VII