Somatosensory Pathways Flashcards
(13 cards)
2nd order sensory neurons convey impulses from the _____ to the _____ and have cell bodies in either the ______ or _____.
Spinal cord or medulla
Thalamus
Spinal cord
Medulla
_______ conduct impulses from the receptors to the spinal cord or ____ and have their cell body located in _____.
1st order sensory neurons
Medulla
Dorsal root ganglion
3rd order sensory neurons have their cell bodies in the _____ and convey impulses from the _____ to the _____ allowing for what?
Thalamus
Thalamus
Cortex (primary motor cortex in postcentral gyrus)
Conscious perception of sensation
What pathway is responsible for conveying
Discriminative touch
Vibration
And CONCIOUS proprioception
What other sensations does this sensory tract convey
Medial lemniscus (posterior columns)
Kinesthesia (awareness of Direction)
Stereognosis (recognition of objects by shape)
Weight discrimination of objects
What receptors are located in the dorsal columns tract?
Discriminative touch= corpuscles of touch and Merkel discs(type 1 cut mechanoreceptors)
Stereognosis= Meissners corpuscles; type 1 receptors and proprioceptors
Vibration= Lamellated/pacinian corpuscles (high frequency) and Meissners corpuscles (low frequency)
Kinesthesia and weigh discrimination = proprioceptors
Describe the pathways of the dorsal columns
1st-fasciculus gracillis
____ component of dorsal columns present throughout spinal cord
Conveys information from ______
1st order neurons synapse with 2nd order in _____ and then 2nd order neurons decussate in _____ which then travel to the ____ to synapse with 3rd order neurons which project to the ______.
2nd-fasciculus cuneatus
Added _____ to dorsal column _____ and above
Provides information from ______ and follows same path except for what changes?
Medial Lower extremity and trunk Nucleus gracilis of medulla Medial lemniscus of medulla Thalamus Primary sensory cortex in post central gyrus
Laterally
T6
Neck upper limbs and upper chest
1st order neuron synapses with 2nd order in nucleus cuneatus of medulla
The anterior Spinothalamic tract conveys what sensory information
What receptors are involved in this tract
Crude touch
Itch
Tickle
Pressure
Lateral spinothalamic tract detects what sensory information
Pain and temperature
Free nerve ending are receptors
Explain the pathway of anterior and lateral spinothalamic tract
1st order neurons from the ______ enter cord via the _____, synapse with 2nd order neurons in a region of the ____grey horn called the ______. 2nd order neurons then decussate in the _____ via the anterior ____ and travel ______ in the anterior and lateral spinothalamic tracts. These neurons then synapse with 3rd order neurons in the ______ which carry impulses to the ____.
Neck, limbs, trunk Posterior Substantia gelatinosa Spinal cord White commissure Superiorly Thalamus Primary somatosensory cortex
How does the spinocerebral tracts differ from the other sensory pathways (2 major ones)
Remains ipsilateral (anterior decussates and recrosses) Involves ONLY 1st and 2nd order neurons
Posterior spinocerebral tract:
Conveys information regarding __________.
Remains ______ as it does not ______.
Receptors include ______ located in the ______.
Pathway :
1st order neurons enter spinal cord via _____; synapse with 2nd order in the ______ and target the _____ via the ______ peduncle of the _____.
Posture balance coordination of skilled movements Ipsilateral Decussate Proprioceptors Legs and lower half of the trunk
Dorsal root Spinal cord posterior grey horn Cerebellum Inferior Medulla
Anterior spinocerebellar tract
Acts as ______ feedback by monitoring activities of _______ and _____ from the cortex to the brainstem.
Receptors include ______
Pathway: 1st order neurons synapse in the _____ and _____ horns of the spinal cord with 2nd order neurons
They then decussate in the _____ via the _______ and ascend to the ______ where most _______ and enter the _____ cerebellar peduncle however some enter the _____ peduncle therefore supplying the cerebellum with information from both sides of the lower body
Internal
Spinal interneurons
Descending Motor signals
Proprioceptors of the upper limb/lower limb & trunk Anterior and lateral Spinal cord Anterior white commissure Midbrain Recross Contralateral superior Ipsilateral superior
A sensory engram is :
A sequence of sensations that is a record of a particular muscle action
Opposite of reflex
