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SPINAL.MCQ
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1993-08-06
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D:Created 14.50 06/08/1993
D:Subject : Physiology
D:Topic : Spinal cord
D:Level : Moderate
D:
D:Authors : Department of Physiology
D: The University
D: Leeds LS2 9NQ
I:MCQ SB 1
G:3
G:1:Dental Students
Q:1,2,3,4,5,6,7,8,9,10,11
G:2:Medical Students
Q:1,2,3,4,5,6,7,8,9,10,11
G:3:Science Students
Q:1,2,3,4,5,6,7,8,9,10,11
T:A
L:2
#:1
G: 10464 1 2 3
S:2
:Lesions involving the lumbosacral dorsal roots entering the
:spinal cord can produce:
B:N:5
B:1:T:1
:deformities of joints
B:2:T:1
:ataxia
B:3:F:1
:Babinski response
B:4:F:1
:exaggerated stretch reflexes
B:5:T:1
:loss of bladder sensation
F:6
:Lesions of the dorsal roots cause sensation to be absent, and this
:can result in over-extension and damage to joints resulting in
:deformities (Charcot's joints), ataxia (a disturbance of gait due in this
:case to absence of feedback from muscle spindles) and loss of bladder
:sensation. Stretch reflexes are absent or reduced, and the Babinski
:response (which is an indicator of Pyramidal tract function) is normal.
E:------
#:2
G: 10464 1 2 3
S:1
:The dorsal columns:
B:N:5
B:1:T:1
:consist mainly of primary afferent axon collaterals
B:2:T:1
:contain fibres which synapses with cuneate and gracile nuclei
B:3:F:1
:carry nociceptive information
B:4:F:1
:contain many unmyelinated axons
B:5:T:1
:carry afferent information from the same side of the body
F:6
:The dorsal columns consist mainly of primary afferent collaterals
:which synapse in the dorsal column nuclei (the cuneate and gracile nuclei)
:on the cells of origin of the medial lemniscus. The lemniscus axons cross
:the midline as they course rostrally through the medulla and end in the
:ventrobasal complex of the contralateral thalamus. The dorsal columns
:do not carry nociceptive information and the axons are myelinated.
E:------
#:3
G: 10464 1 2 3
S:1
:Presynaptic inhibition:
B:N:5
B:1:T:1
:is mediated by synapses between axons
B:2:F:1
:is mediated by synapses between axons and cell bodies
B:3:T:1
:operates by reducing transmitter release
B:4:T:1
:can be observed at primary afferent terminals in the dorsal horn
B:5:T:1
:allow selective inhibition of different afferent inputs to a cell
F:10
:Presynaptic inhibition as opposed to postsynaptic inhibition does not
:depend for its effect on hyperpolarisation of the postsynaptic neurone.
:Instead inhibition occurs because of reduction in the output of
:transmitter from afferent terminals, the amount released per impulse
:being reduced by the action of synapses on the terminals (axo-axonic
:synapses). These synapses reduce the membrane potential (and increase
:the excitability) of nerve terminals and when an action potential
:propagates into them the total voltage change during the spike is less
:than normal. The amount of transmitter output is related to voltage
:change during the spike.
E:------
#:4
G: 10464 1 2 3
S:1
:The spinothalamic tracts convey sensations of:
B:N:5
B:1:T:1
:crude touch
B:2:F:1
:discriminative touch
B:3:T:1
:pain
B:4:F:1
:conscious proprioception
B:5:T:1
:temperature
F:4
:The spinothalamic tracts convey crude touch, pain and temperature
:sensation. Discriminative touch (fine two-point discrimination, the
:ability to read Braille and discriminate between different textures) and
:joint position depend on the dorsal columns and medial lemniscus.
E:------
#:5
G: 10464 1 2 3
S:1
:Consider the pathways which transmit noxious information:
B:N:5
B:1:F:2
:the spinothalamic tract terminates in the ventrobasal nuclei of the
:thalamus
B:2:T:2
:the spinothalamic tract terminates in the posterior and lateral
:nuclei of the thalamus
B:3:T:2
:some pain pathways that terminate in the thalamus are polysynaptic
:and synapse in the brainstem
B:4:F:2
:the primary cortical receiving area in the postcentral gyrus receives
:a projection from some cutaneous nociceptors
B:5:T:2
:the second somatosensory receiving area receives a projection from
:some cutaneous nociceptors
F:6
:The posterolateral group of thalamic nuclei receive noxious input
:from the spinothalamic tract and a polysynaptic pathway which synapse
:in the brainstem. The ventrobasal nuclei of the thalamus and the primary
:somatosensory cortex do not deal with noxious information but A delta
:(fast pain) nociceptive pathways do project to the second somatosensory
:receiving area.
E:------
#:6
G: 10464 1 2 3
S:1
:The following are descending tracts:
B:N:5
B:1:F:1
:lateral spinothalamic tract
B:2:T:1
:lateral corticospinal tract
B:3:F:1
:anterior spinothalamic tract
B:4:F:1
:spinoreticular tract
B:5:T:1
:lateral reticulospinal tract
F:4
:Tracts are usually named according to their origin and their
:destination. Thus the spinothalamic tract ascends from the spinal cord
:to the thalamus, and the corticospinal tract descends from the cortex to
:the spinal cord.
E:------
#:7
G: 10464 1 2 3
S:1
:The signs of a dorsal column lesion include;
B:N:5
B:1:F:1
:loss of pain and temperature sensation on the opposite side
B:2:F:2
:loss of the sense of position and passive movement on the opposite
:side
B:3:T:1
:loss of touch sensation on the same side
B:4:T:1
:loss of joint sensibility on the same side
B:5:F:1
:absence of sensation from the viscera
F:2
:The dorsal columns carry information about touch, vibration and joint
:position on the same side of the body.
E:------
#:8
G: 10464 1 2 3
S:1
:The following are descending tracts:
B:N:5
B:1:F:1
:lateral spinothalamic tract
B:2:T:1
:lateral corticospinal tract
B:3:F:1
:anterior spinothalamic tract
B:4:F:1
:spinoreticular tract
B:5:T:1
:lateral reticulospinal tract
F:4
:Tracts are usually named according to their origin and their
:destination. Thus the spinothalamic tract ascends from the spinal cord
:to the thalamus, and the cortico-spinal tract descends from the cortex
:to the spinal cord.
E:------
#:9
G: 10464 1 2 3
S:1
:Consider Renshaw cells:
B:N:5
B:1:T:1
:they are excited by a projection form alpha motoneurones
B:2:T:1
:they conduct spikes at up to 1500 per s
B:3:F:1
:they are inhibited by acetylcholine
B:4:T:1
:they project to other interneurons
B:5:T:1
:they project to alpha motoneurones
F:4
:Renshaw receive axon collaterals from alpha motoneurones, and the
:excited by acetyl choline that is released by these terminals. They can
:discharge at very high rates for short periods and project to alpha
:motoneurones and Ia inhibitory interneurons.
E:------
#:10
G: 10464 1 2 3
S:2
:Consider the efferent neurones in the intermediolateral column
:of the thoracic cord:
B:N:5
B:1:F:1
:they have axons in the dorsal roots
B:2:F:1
:they contain noradrenaline
B:3:T:1
:they receive inputs from the ventral medulla
B:4:T:1
:they are reflexly excited by bladder distension
B:5:F:1
:they are excited by stimulation of the pyramidal tract
F:4
:The sympathetic efferents of the intermediolateral column have axons
:in the ventral roots which release acetylcholine. These neurones are
:under the control of the ventral medulla (cardiovascular centres) and
:can be reflexly excited by visceral afferents.
E:------
#:11
G: 10464 1 2 3
S:2
:Consider the efferent neurones in the intermediolateral column
:of the thoracic cord:
B:N:5
B:1:F:1
:they have axons in the dorsal roots
B:2:F:1
:they contain noradrenaline
B:3:T:1
:they receive inputs from the ventral medulla
B:4:T:1
:they are reflexly excited by bladder distension
B:5:F:1
:they are excited by stimulation of the pyramidal tract
F:4
:The sympathetic efferents of the intermediolateral column have axons
:in the ventral roots which release acetylcholine. These neurones are
:under the control of the ventral medulla (cardiovascular 'centres'), and
:can be reflexly excited visceral afferents.
E:------
::