Brainstem 1 Flashcards
if there is a “bump” in the nervous system, what is it created by?
- huge collection of fibers
- huge collection of cell bodies (nuclei)
anatomically significant structures on the ventral surface of the medulla:
- anterior median fissure
- pyramids
- pre and post olivary sulcus
- pyramidal decussation
the pyramids are part of what?
corticospinal tract
what CNs exit the pontomedullary junction?
medial to lateral:
- CN6
- CN7
- CN8
what CN exits laterally from the pons?
CN 5
the groove that runs midline in the pons transmits what structure?
vertebral a.
CNs that exit the pontomesocephalic junction?
- CN 3 comes out medially
- CN 4 from back behind on the dorsal surface
anatomically significant structures of the mesencephalon:
-cerebral peduncles
what do the cerebral peduncles represent?
- corticospinal tract
- goes on to decrease in size as the pyramids in the medulla
- b/c many of its axons stop in the pons
where does pons send info?
cerebellum
modality of the cerebellum
MOTOR
if you lesion below the pyramidal decussation, where will the defect be?
ipsilateral motor defect
if you lesion above the pyramidal decussation, where will the defect be?
contralateral motor defect
CN that exits the brainstem through the pre olivary sulcus:
CN 12
CNs that exit the brainstem through the post olivary sulcus:
from top down:
- CN 9
- CN 10
- CN 11
on the dorsal surface of brainstem, what is the connection from the pons to the cerebellum?
3 peduncles
- superior
- middle
- inferior
what is the space b/w the the connection of the pons and cerebellum?
4th ventricle
anatomically significant structures on the dorsal surface of the medulla:
- fasciculus gracilis
- fasiculus cuneatus
- tuberculum gracilis
- tuberculus cuneatus
- foramen of magandie
- foramen of luschka
structures on floor of 4th ventricle:
- facial colliculus
- hypoglossal trigonum
structures on dorsal surface of the mesencephalon
- superior colliculus
- inferior colliculus
superior colliculus
relay nuclei for vision
inferior colliculus
related to hearing
in the pathway of gracilis and cuneatus, where are the first and second order neurons located?
- 1st order neurons ascend on same side
- 2nd order synapse and decussate in medulla - creating the nuclei and overlying tuberulum
only CN to exit the brainstem from dorsal surface?
CN 4
biggest nucleus in the brainstem?
trigeminal
trigeminal nucleus modalities
- mesencephalic trigeminal nucleus = proprioception (TMJ)
- main trigeminal nucleus = touch
- nucleus of spinal tract = pain and temp
vestibular nuclei modality
balance
cochlear nucleus modality
hearing
nucleus of solitary tract modality
- taste
- visceral afferents
distribution of nuclei in the brainstem
- some are only located in 1 part (ex: hypoglossal)
- some are elongated
- keep in mind that it’s 3D
closed medulla
below 4th ventricle
open medulla
above the 4th ventricle
the 4th ventricle continue inferiorly as what?
the central canal of the SC
nervous system embryological development
- 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
what is the top portion of the developing neural tube?
- alar plate
- sensory
- formation of dorsal horn
what is the bottom half of the developing neural tube?
- basal plate
- motor
- ventral horn development
solitary nucleus
- modality
- CNs
- taste and VA
- 7
- 9
- 10
trigeminal tract and nucleus
- modality
- CNs
- somatic sensation
- 5
- 7
- 9
- 10
What are the 4 preganglionic parasymptathic nuclei?
- Edinger-wesphal
- inferior salivatory
- superior salivatory
- DMN of 10
edinger-westphal nucleus is for what CN?
CN 3
superior salivatory nucleus is for what CN?
CN 7
inferior salivatory nucleus is for what CN?
CN 9
What are the 4 motor nuclei?
- Nucleus ambiguous
- facial nucleus
- masticatory nucleus
- spinal accessory nucleus
what CNs use nucleus ambiguous?
- CN 9
- CN 10
- CN 11
what CN uses the masticatory motor nucleus?
CN 5
what are the main structures you would find in a cross section of the closed medulla?
- nucleus gracilis and cuneatus
- ventral horn of C1
- pyramidal decussation
- spinal nucleus of CN 5
in a closed medulla cross section, why do you see the ventral horn of C1 but no dorsal horn?
- 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
what are the main structures you would find in a cross section of the open medulla?
- 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)
medial lemniscus
- ascending axons of 2nd order neurons from the gracilis and cuneate nuclei
- heading to VPL of thalamus
solitary nucleus and tract
- sensory relay tract for taste and visceral afferents
- CNs: 7, 9 and 10
DMN of CN 10
- visceral efferents
- preganglionic parasymptatics of 10 leave from here
- note that the motor and sensory go to different nuclei (sensory at solitary nucleus)
descending spinal tract of CN 5
- somatic afferents
- descending b/c it enters at Pons and has to descend to synapse
nucleus ambiguous
- motor (midline) nucleus that innervates muscles that are branchiomeric in origin
- ex: trapezius and sternocleidomastoid
CN associated w/ nucleus ambiguous?
- CN 11
- easy to remember b/c spinal accessory n. innervated trap. and sternoclediomastoid
hypoglossal nucleus
- somatic efferents
- midline so motor
a lesion at the hypoglossal nuclues would be:
- LMN lesion
- same as lesioning the ventral horn
- it’s the final common pathway
- ipsilateral defect
- deviation of the tongue
where do you find the vestibular and cochlear nuclei?
pontomedullary junction
vestibular nuclei
- 4 of them
- one gives rise to vesibulospinal tract
- balance
cochlear nuclei
- 2 of them
- hearing
inferior olivary nucleus
relay of motor function
lesion at the pyramids:
- UMN lesion
- effect would be contralateral b/c above the decussation
