Sensory and Motor Circuits Flashcards by Caitlin Nicholson

The descending long tracts carry…..

The ascending long tracts carry….

Motor info from the cortex

Sensory info to the cortex

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If an axon is damaged, everything _____ to the lesion dies and all information destined for _____ parts is disrupted.

Distal and distal

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The ventral posteriolateral nucleus of the thalamus receives information from ____ and projects to ____

Epicritic and protopathic sensation of the trunk and limbs

Postcentral gyrus

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The ventral posteriomedial nucleus of the thalamus receives information from ____ and projects to ____

Epicritic and protopathic sensation of the head and neck

Postcentral gyrus

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Name and define the 3 different types of sensation

Epicritic- 2-point discrimination, fine touch, vibration and position sense
Protopathic- pain and temperature
Proprioceptive- where your body part is

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What are the 4 somatosensory circuits?

Lemniscal, Anterolateral, Spino-cerebellar and Trigeminal

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The lemniscal system conveys ____ sensation from ____

Epicritic

Trunk and limbs

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In the lemniscal system, axons from the lower trunk and limbs travel in the ____ and axons from the upper trunk and limbs travel in the _____ on the _____ side of the body. Both of these axon bundles are in the _____

Gracile fasciculus (lower body)
Cuneate fasciculus (upper body)
Ipsilateral (same) side of the body
Dorsal column of the spinal cord

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In the lemniscal system, the fasciculi synapse in the ______ in the _____ at which point they cross to the other side (aka the ______) and are renamed the ________

gracile and cuneate nuclei respectively
In the medulla
Sensory decusation or internal arcuate fibers
Medical lemniscus

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The medical lemniscus synapses in the ______ in the thalamus and may be carried to the ______ by third order neurons

VPL

Primary somatosensory cortex

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Axons entering the lemniscal system are of ______ diameter whereas the axons entering the anterolateral system are of ____ diameter

Large

Small

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In the anterolateral system, neurons synapse _______ and ascend in the ______

almost immediately (and cross almost immediately too)
Anterolateral white matter of the spinal cord

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Most axons of the anterolateral pathway synapse at ________ but some continue on to the ______ if they are destined for the primary somatosensory cortex

reticular formation

VPL of the thalamus

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The anterolateral pathway conveys _____ sensation and a lesion would present as ______

Protopathic

reduced protopathic sensation on the opposite side of the body

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Damage to the lemniscal system at the level of the gracile fasciculus would cause deficits on _____ side of the body. How about to the medial lemniscus?

Gracile fasciculus- ipsilateral

Medial lemniscus- contralateral

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in the spino-cerebellar system, axons for the lower body enter via the dorsal roots and ascend as the _____. They synapse in the _____ and second order axons ascend as the _____

Gracile fasciculus
Dorsal nucleus of Clarke
Dorsal spinocerebellar tract

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Axons from the arm and upper trunk for the spino-cerebellar tract ascends via the ______ where they synapse in the _____ and then travel as the _____

cuneate fasciculus
accessory/lateral cuneate nucleus
cuneo-cerebellar tract

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The spino-cerebellar tract conveys _____ sensation to the ______ side of the cerebellum. Both tracts enter via the ______

Proprioceptive
same
Inferior cerebellar peduncle

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The trigeminal system conveys _____ sensation from the _____

epicritic, protopathic, and proprioceptive

face and neck

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The epicritic neurons of the trigem system synapse in the ____ in the ____ and cross the midline to join the _____ to travel to the ____

chief sensory nucleus of Cr. V
Pons
medial lemniscus
VPM of the thalamus

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A lesion to the epicritic system of trigem would cause symptoms on the ____ side if in the pons and on the ____ side if in the medial lemniscus

Same= pons
Opposite= medial lemniscus

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The protopathic neurons of the trigem system descend as the _____ and synapse in the ____. These neurons cross the midline and project to the ____. 3rd order neurons project to the ____

spinal tract of 5
spinal nucleus of 5
reticular formation
VPM of the thalamus

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A lesion to the protopathic fibers of the trigem system in the medulla causes symptoms _____. In the reticular formation, causes _____

On the same side

On the opposite side

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The pyramidal system is a ______ system with ______ cortical control. The brainstem-spinal system is a _____ system with _____ cortical control.

both are motor systems
Pyramidal- direct control
Brainstem-spinal- indirect control

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The corticobulbar tract of the pyramidal system descends through the _____ and controls axons of the ____. A unilateral lesion here will cause ______

brainstem cranial nerve nuclei weakness of head and neck movement on the contralateral side for the Cr nerves rostral to the lesion

The corticospinal tract of the pyramidal system controls ______. It descends through the brainstem on the same side; most axons cross in the ______ and continue as the ______. The axons that don't cross form the ______

Motor neurons of the trunk and limbs caudal medulla lateral corticospinal tract anterior corticospinal tract

The lateral corticospinal tract controls ____ and the anterior corticospinal tract controls ______. Both tracts synapse with neurons in the _____

fine motor control and voluntary movements axial muscles and postural muscles ventral horn of the spinal cord

Pathology of the corticospinal tract in the brainstem results in _____. Pathology in the spinal cord results in_____.

Lesion to the opposite side | Lesion to the same side

The brainstem-spinal pathway is made up of 4 pathways. Name them and state what they control

tecto-spinal tract- orients head movements based on visual/auditory stimuli reticulo-spinal tract- balance and posture vestibulo-spinal tract- maintaining balance and posture; processing changes in head position rubro-spinal tract- fine motor control (w/ corticospinal tract)

The brainstem-spinal pathway originates in the ____. A lesion in the brainstem will cause _____. A lesion in the spinal cord will cause ______

brainstem Pathology of the opposite side Pathology of the same side

For vision, axons of the _____ retina cross at the optic chiasm and axons for the _____ retina do not

Nasal cross | Temporal do not

Axons from the retina can terminate in the....

LGN, superior colliculus, hypothalamus

The temporal radiations convey _____ visual field info from the LGN to the _____ bank of the calcarine sulcus. Parietal radiations convey ______ VF info to the ____ bank.

Temporal- superior VF, inferior bank | Parietal- inferior field, superior bank

The hypothalamus is important in...

circadian rhythms

the superior colliculus is important in...

moving the head, eyes and axial muscles

The pupillary light reflex begins when axons from Cr 2 bypass the LGN and synapse at the ______ of the ______ side

The edinger-westphal nucleus | the same and contralateral (bilateral innervation!)

Pupillary light reflex: The EW nucleus sends off pregang paras which travel with ____ to the ciliary ganglion where they synapse and travel as short ciliary nerves to innervate the ____ muscle

Cr 3 | Ciliaris

Auditory deficits in 1 ear indicate...

damage to Cr. 8 or to the cochlear nuclei

Auditory deficits in both ears suggest... because

damage to both Cr. 8s or bilateral temporal lobe damage | second-order neurons cross in the caudal pons so there is a lot of bilateral mixing of hearing

Cr 8 carries auditory info from the cochlea to the _____ nucleus. From there, info heads to the _____ then ascends the brainstem in the _____ which terminates in the ____ which projects to the MGN via the ______. The information is then sent to _____ via the auditory radiations in the posterior limb of the internal capsule

``` cochlear (dorsal and ventral) superior olive lateral lemniscus Inferior colliculus brachium of the inferior colliculus Heschl's gyrus ```

At what points does information cross in the auditory pathway? What impact does this have for a lesion?

At the superior olives (each cochlear nucleus projects to both superior olives) and at the inferior colliculi To have hearing loss in 1 ear, a lesion must be in Cr. 8 or the cochlear nucleus on 1 side

Possible loss of consciousness signals a _____ issue

Vascular

Why does an UMN lesion cause hyperreflexia?

UMNs exert inhibitory control on LMNs so a UMN lesion causes hyperreflexia b/c of the loss of inhibitory control

Cell bodies of the neurons in the corticospinal tract are located in the _______. Their axons pass through the ____ and the ______ to the medulla, where they cross as the pyramidal decusation

``` Precentral gyrus (primary motor cortex) Post limb internal capsule Crus cerebri ```

A patient with hemineglect (of the L side of the body) likely has a lesion in....

The R hemisphere, in the parietal lobule (corresponds to Wernicke's and Broca's areas in the L hemisphere)

If both temporal visual fields are not present, this can only occur b/c of a lesion to .....

the optic chiasm

What cranial nerves are responsible for the corneal reflex?

5 (sensation) and 7 (motor)

What cranial nerve is involved in the jaw reflex?

What cranial nerves are involved in the gag reflex? What else are they involved in?

9 and 10 | Soft palate elevation

The _____ abuts the optic chiasm so a tumor here can cause VF deficits (nonhomonymous temporal field)

pituitary

What do finger-to-nose and heel-to-shin tests test for?

a cerebellar lesion

What is Romberg's sign? What does it tell you?

Have a patient stand up with feet together and close eyes. If normal, patient doesn't wobble. If pt wobbles- if can correct balance by opening eyes-> posterior column disorder (i.e. proprioception) If can't correct by opening eyes -> cerebellar problem

What is alexia? Damage to what areas can cause this?

A type of aphasia- inability to read because of damage to the angular gyrus which brings info from area 17 to Wernicke's area Note: damage must be bilateral to cause alexia b/c the splenium of the corpus callosum can still bring info to the working side with a unilateral lesion thus preventing alexia

Transient visual loss signals transient ischemic attacks which suggests....

a stroke (as etiology)

How is it possible that a patient cannot read but can write?

Broca's and Wernicke's areas are important for writing and they can be intact but the angular gyri could be affected bilaterally, affecting the pt's ability to read

Word deafness or the inability to recognize words as language is because of ....

a lesion to the auditory cortex

Is alexia a deficit in language, cognition or memory?

Language. it's a type of aphasia

Where are the cell bodies of the sensory neurons in the lemniscal system located?

In the DRGs (dorsal root ganglia)

The neurons in the anterolateral/spinothalamic system might ______ then cross over _____ before ascending into the brain stem

travel up or down 1-2 levels | almost immediately

A VF deficit in the bottom L of your visual field (inferior temporal) signals a lesion....

in the top R-> parietal radiations on R side | think inverted and flipped

The anterior nucleus of the thalamus receives input from the _____ and sends output to the ____ and is involved in ______

Mamillary bodies/hypothalamus Cingulate gyrus emotions

The ventral anterior and ventral lateral nuclei of the thalamus are involved in _____. They receive projections from the ____ and project to _____

Motion Cerebellum and globus pallidus premotor cortex (and ventral lateral also projects to the precentral gyrus/primary motor cortex)

Sensory and Motor Circuits Flashcards

(62 cards)