Quiz 3 Flashcards
Somatosensory pathways process information about what?
somatic sensations - pain, temperature, touch, proprioception & vibration
dorsal column/medial lemniscus pathway
light touch & conscious proprioception
anterolateral column/spinothalamic tract
discrimintive (fast) nocioception & temperature & crude touch
what is light touch?
the localization of touch & vibration & the ability to discriminate between two closely space points touching the skin
light touch is sensed by what? and what are they called?
mechanoreceptors
merkel disks & meisner corpuscles in the upper dermis
what is conscious proprioception?
the awareness of the movements & relative position of body parts
conscious proprioception is sensed by what? and where are they?
mechanoreceptors
muscles (muscle spindles), tendon/muscle junctions (golgi tendons), & deep dermis (ruffini endings)
pathway for light touch & conscious proprioception – upper limb
1st order: travels in fasciculus cuneatus & synapses in nucleus cuneatus in medulla
2nd order: axons travel in medial lemniscus to thalamus
3rd order: neuron conveys information from the thalamus to the primary somatosensory cortex
pathway for light touch & conscious proprioception – lower limb and trunk
1st order: travels in fasciculus gracilis & synapses in nucleus gracilis in medulla
2nd order: axons travel in medial lemniscus to thalamus
3rd order: neuron conveys information from the thalamus to the primary somatosensory cortex
primary somatosensory cortex receives what?
somatotopically organized information & discriminates the size, texture, & shape of objects
secondary somatosensory cortex analyzes what? and provides what?
analyzes information from the primary sensory area & the thalamus
provides stereognosis & memory of the tactile & spatial environment
what is homunculus?
a map developed by recording the responses of awake individuals during surgery
lesions BELOW decussation in medulla results in what?
ipsilateral loss of sensation
lesions ABOVE decussation in medulla results in what?
contralateral loss of sensation
fast nociception / temperature / crude touch pathway – from the body
1st order: dorsal root ganglion
2nd order: dorsal horn of spinal cord
3rd order: VPL nucleus of thalamus
fast nociception / temperature / crude touch pathway – from the face
1st order: trigeminal ganglion
2nd order: spinal nucleus of trigeminal nerve
3rd order: VPM nucleus of thalamus
what does the cerebellum do?
adjusts posture and coordinates movement
cerebellum & spinocerebellar pathways integrate intended movement information from the frontal lobe with sensory information from:
vestibular receptors
proprioceptors
motor areas in brainstem & ventral horn of spinal cord
the cerebellum can be divided vertically into 3 functional regions:
vermis
paravermis
lateral hemispheres
what is the functional name of the vermis & paravermal region of the cerebellum?
spinocerebellum
spinocerebellum receives sensory information to do what?
make anticipatory & corrective & responsive adjustments to movement
what are the 2 general types of spinocerebellar pathways?
- high-fidelity pathways
- internal feedback tracts
what do the high-fidelity pathways do?
deliver information from peripheral receptors in muscles, tendons, & joints to cerebellum
what do the internal feedback tracts do?
provide information about spinal interneurons & descending motor tracts to cerebellum
what are the two high-fidelity pathways?
- posterior spinocerebellar pathways
- cuneocerebellar pathway
what does the posterior spinocerebellar pathway do?
transmits proprioceptive information from the lower limb and the lower trunk to the cerebellum
order of posterior spinocerebellar pathway:
1st order: (cell body in DRG, peripheral receptor in lower limb/lower trunk) synapses in nucleus dorsalis of lumbar spinal cord
2nd order: axons form the posterior spinocerebellar tract that travels ipsilaterally through inferior cerebellar peduncle to cerebellar cortex
what does the cuneocerebellar pathway do?
Transmits proprioceptive information from from proprioceptors in the neck, upper limb, and upper half of the trunk
order of cuneocerebellar pathways:
1st order: neuron (cell body in DRG, peripheral receptor in upper limb) travels in dorsal columns and synapses in lateral cuneate nucleus of the lower medulla
2nd order: axons form the cuneocerebellar tract and ascend the medulla, then travel in the inferior cerebellar peduncle to the ipsilateral cerebellar cortex
what are the 2 internal feedback tracts?
- anterior spinocerebellar tracts
- rostrospinocerebellar tracts
what does the anterior spinocerebellar tract?
Transmits information from the thoracolumbar gray matter
in the spinocerebellar tract the axons decussate & ascend where?
in the contralateral anterior spinocerebellar tract to the midbrain
spinocerebellar tract divides in ________: some _______ others remain __________
midbrain
decussate
ipsilateral
spinocerebellar tract enters cerebellum via what?
superior cerebellar peduncles
each cerebellar hemisphere receives info from both sides of where?
the lower body
what does the rostrospinocerebellar tract do?
Transmits information from the cervical spinal cord and T1 to the ipsilateral cerebellum
rostrospinocerebellar tract enters the cerebellum via where?
the inferior and superior cerebellar peduncles
medial motor tracts
- reticulospinal tract
- medial corticospinal tract
- medial vestibulospinal tract
- lateral vestibulospinal tract
lateral motor tracts
- rubrospinal tract
- lateral corticospinal tract
pyramidal tracts originate where?
the motor cortex
what do pyramidal tracts do?
carry motor fibers to the spinal cord & brainstem
what are pyramidal tracts responsible for?
the voluntary control of the skeletal muscles of the body and face
extrapyramidal tracts originate where ?
the brainstem
what do extrapyramidal tracts do?
carry motor fibers to the spinal cord
what are extrapyramidal tracts responsible for?
the involuntary and automatic control of muscle tone, balance, posture and modulation of motor plans
what do medial motor tracts do?
controls posture and gross movements that usually occurs automatically, without conscious effort
what are the three tracts of the medial motor tract?
- reticulospinal tract
- medial & lateral vestibulospinal tracts
- medial corticospinal tract
medial corticospinal tract facilitates motor neurons to:
neck, shoulder & trunk muscles
reticulospinal tract facilitates motor neurons to:
bilateral postural muscles & gross limb movement muscles of entire body
lateral vestibulospinal tract facilitates motor neurons to:
postural muscles
medial vestibulospinal tract facilitates motor neurons to:
neck
what is fractionation?
the ability to activate individual muscles independently of other muscles
Two MTs that descend the lateral spinal cord and synapse with laterally located lower MN pools in ventral horn:
- rubrospinal
- lateral corticospinal
rubrospinal tract has minor contribution to what?
the control of upper limb flexor muscles in adults
rubrospinal tract arises in what?
the red nucleus of the midbrain, where the axons decussate before descending to synapse on contralateral MNs innervating wrist and finger flexors
rubrospinal tract is where?
upper motor neuron in red nucleus
lateral corticospinal tract is where?
upper motor neuron in motor cortex
lateral corticospinal tract fractionates how?
by activating inhibitory neurons to prevent unwanted muscles from contracting
what is the most important pathway for controlling voluntary movement of limbs?
lateral corticospinal tract
in the lateral corticospinal tract where do most fibers decussate?
in pyramids of medulla (pyramidal decussation)
Paths of corticospinal tracts are in the what?
brain
Corticospinal neuron cell bodies are in the what?
cerebral cortex
the corticospinal tract axons travel through the:
- corona radiata
- internal capsule
- cerebral peduncles
- anterior pons
- medullary pyramids (most fibers decussate here)
- spinal cord
