Brainstem 1

Question 1

if there is a “bump” in the nervous system, what is it created by?

Answer 1

• huge collection of fibers

- huge collection of cell bodies (nuclei)

Question 2

anatomically significant structures on the ventral surface of the medulla:

Answer 2

• anterior median fissure
• pyramids
• pre and post olivary sulcus
• pyramidal decussation

Question 3

the pyramids are part of what?

Answer 3

corticospinal tract

Question 4

what CNs exit the pontomedullary junction?

Answer 4

medial to lateral:

• CN6
• CN7
• CN8

Question 5

what CN exits laterally from the pons?

Answer 5

CN 5

Question 6

the groove that runs midline in the pons transmits what structure?

Answer 6

vertebral a.

Question 7

CNs that exit the pontomesocephalic junction?

Answer 7

• CN 3 comes out medially

- CN 4 from back behind on the dorsal surface

Question 8

anatomically significant structures of the mesencephalon:

Answer 8

-cerebral peduncles

Question 9

what do the cerebral peduncles represent?

Answer 9

• corticospinal tract
• goes on to decrease in size as the pyramids in the medulla
• b/c many of its axons stop in the pons

Question 10

where does pons send info?

Answer 10

cerebellum

Question 11

modality of the cerebellum

Answer 11

MOTOR

Question 12

if you lesion below the pyramidal decussation, where will the defect be?

Answer 12

ipsilateral motor defect

Question 13

if you lesion above the pyramidal decussation, where will the defect be?

Answer 13

contralateral motor defect

Question 14

CN that exits the brainstem through the pre olivary sulcus:

Answer 14

CN 12

Question 15

CNs that exit the brainstem through the post olivary sulcus:

Answer 15

from top down:

• CN 9
• CN 10
• CN 11

Question 16

on the dorsal surface of brainstem, what is the connection from the pons to the cerebellum?

Answer 16

3 peduncles

• superior
• middle
• inferior

Question 17

what is the space b/w the the connection of the pons and cerebellum?

Answer 17

4th ventricle

Question 18

anatomically significant structures on the dorsal surface of the medulla:

Answer 18

• fasciculus gracilis
• fasiculus cuneatus
• tuberculum gracilis
• tuberculus cuneatus
• foramen of magandie
• foramen of luschka

Question 19

structures on floor of 4th ventricle:

Answer 19

• facial colliculus

- hypoglossal trigonum

Question 20

structures on dorsal surface of the mesencephalon

Answer 20

• superior colliculus

- inferior colliculus

Question 21

superior colliculus

Answer 21

relay nuclei for vision

Question 22

inferior colliculus

Answer 22

related to hearing

Question 23

in the pathway of gracilis and cuneatus, where are the first and second order neurons located?

Answer 23

• 1st order neurons ascend on same side

- 2nd order synapse and decussate in medulla - creating the nuclei and overlying tuberulum

Question 24

only CN to exit the brainstem from dorsal surface?

Answer 24

CN 4

Question 25

biggest nucleus in the brainstem?

Answer 25

trigeminal

Question 26

trigeminal nucleus modalities

Answer 26

1. mesencephalic trigeminal nucleus = proprioception (TMJ) 2. main trigeminal nucleus = touch 3. nucleus of spinal tract = pain and temp

Question 27

vestibular nuclei modality

Answer 27

balance

Question 28

cochlear nucleus modality

Answer 28

hearing

Question 29

nucleus of solitary tract modality

Answer 29

- taste | - visceral afferents

Question 30

distribution of nuclei in the brainstem

Answer 30

- some are only located in 1 part (ex: hypoglossal) - some are elongated - keep in mind that it's 3D

Question 31

closed medulla

Answer 31

below 4th ventricle

Question 32

open medulla

Answer 32

above the 4th ventricle

Question 33

the 4th ventricle continue inferiorly as what?

Answer 33

the central canal of the SC

Question 34

nervous system embryological development

Answer 34

- started out as tube w/ central canal lined w/ ependymal cells - divided into upper and lower half by sulcus limitans - medulla began to open up at midline to form 4th ventricle - midline stayed motor - periphery stayed sensory

Question 35

what is the top portion of the developing neural tube?

Answer 35

- alar plate - sensory - formation of dorsal horn

Question 36

what is the bottom half of the developing neural tube?

Answer 36

- basal plate - motor - ventral horn development

Question 37

solitary nucleus - modality - CNs

Answer 37

- taste and VA - 7 - 9 - 10

Question 38

trigeminal tract and nucleus - modality - CNs

Answer 38

- somatic sensation - 5 - 7 - 9 - 10

Question 39

What are the 4 preganglionic parasymptathic nuclei?

Answer 39

- Edinger-wesphal - inferior salivatory - superior salivatory - DMN of 10

Question 40

edinger-westphal nucleus is for what CN?

Answer 40

CN 3

Question 41

superior salivatory nucleus is for what CN?

Answer 41

CN 7

Question 42

inferior salivatory nucleus is for what CN?

Answer 42

CN 9

Question 43

What are the 4 motor nuclei?

Answer 43

- Nucleus ambiguous - facial nucleus - masticatory nucleus - spinal accessory nucleus

Question 44

what CNs use nucleus ambiguous?

Answer 44

- CN 9 - CN 10 - CN 11

Question 45

what CN uses the masticatory motor nucleus?

Answer 45

CN 5

Question 46

what are the main structures you would find in a cross section of the closed medulla?

Answer 46

- nucleus gracilis and cuneatus - ventral horn of C1 - pyramidal decussation - spinal nucleus of CN 5

Question 47

in a closed medulla cross section, why do you see the ventral horn of C1 but no dorsal horn?

Answer 47

- there is no C1 dorsal root (1st dermatome is C2) - the spinal nucleus of CN 5 is the substition of the dorsal horn - represents the transition of body sensation to face sensation

Question 48

what are the main structures you would find in a cross section of the open medulla?

Answer 48

- MLF - hypoglossal nucleus - DMN of CN 10 - solitary nucleus and tract - cochlear nuclei - vestibular nuclei - nucleus ambiguous - descending spinal tract of CN 5 - inferior olivary nucleus - medial lemniscus - pyramids (corticospinal tract)

Question 49

medial lemniscus

Answer 49

- ascending axons of 2nd order neurons from the gracilis and cuneate nuclei - heading to VPL of thalamus

Question 50

solitary nucleus and tract

Answer 50

- sensory relay tract for taste and visceral afferents | - CNs: 7, 9 and 10

Question 51

DMN of CN 10

Answer 51

- visceral efferents - preganglionic parasymptatics of 10 leave from here - note that the motor and sensory go to different nuclei (sensory at solitary nucleus)

Question 52

descending spinal tract of CN 5

Answer 52

- somatic afferents | - descending b/c it enters at Pons and has to descend to synapse

Question 53

nucleus ambiguous

Answer 53

- motor (midline) nucleus that innervates muscles that are branchiomeric in origin - ex: trapezius and sternocleidomastoid

Question 54

CN associated w/ nucleus ambiguous?

Answer 54

- CN 11 | - easy to remember b/c spinal accessory n. innervated trap. and sternoclediomastoid

Question 55

hypoglossal nucleus

Answer 55

- somatic efferents | - midline so motor

Question 56

a lesion at the hypoglossal nuclues would be:

Answer 56

- LMN lesion - same as lesioning the ventral horn - it's the final common pathway - ipsilateral defect - deviation of the tongue

Question 57

where do you find the vestibular and cochlear nuclei?

Answer 57

pontomedullary junction

Question 58

vestibular nuclei

Answer 58

- 4 of them - one gives rise to vesibulospinal tract - balance

Question 59

cochlear nuclei

Answer 59

- 2 of them | - hearing

Question 60

inferior olivary nucleus

Answer 60

relay of motor function

Question 61

lesion at the pyramids:

Answer 61

- UMN lesion | - effect would be contralateral b/c above the decussation