Term
| Name the five sensory receptors of the Ascending Motor Tracks |
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Definition
- Mechanoreceptors - tapping, touch, vibration, stretch, tactile & positional
- Thermoreceptors - temp change
- Nociceptors - pain
- Electromagnetic - light energy
- Chemoreceptors - glucose & oxygen uptake
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Term
| Sensory receptors are based on their adaptation speed |
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Definition
Slow adapting receptors = muscle spindle or pain receptors - more tonic
Rapidly adapting receptors = hair end organ - more phasic |
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Term
General classification of sensory receptors
name the 3 |
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Definition
- Exteroreceptive = responds to external environment
- Proprioceptive = positions of the body in space
- Interoreceptive = responds to internal changes
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Term
Mechanoreceptors
(tactile receptors - 2) |
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Definition
- Meissener's corpuscles = most superficial with elongated capsules lying in epidermis; finger pads, rapidly adapting, sensitive to light objects over skin and low frequency vibration; purpose-hand texture objects and adaptability fast and rapid.
- Merkel's cell disc = incapsulated endings and found in smooth skin; deep in epidermis sensitive to pressure, location - densely in distal phalanx; purpose - pressure- adaptability is slow - looks like a bullseye
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Term
Mechanoreceptors
(continued 2 more) |
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Definition
- Pacinian corpuscles = deep in dermis-onion slice, purpose HIGH frequency vibration; rapidly adaptable
- Ruffini endings = location - dermis, jt and nerve fiber; purpose - skin stretch or conscious touch/pressure; slow adaptability
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Term
Mechanoreceptors
(continued 1 ) |
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Definition
- Hair end organ/peritrichial plexi = deep dermis and epidermis; purpose - alerting body to environment; rapid adaptability
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Term
| Mechanoreceptors are responsible for: |
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Definition
Position (static and rate of mvmt)
Proprioception
Kinesthesia
- pacinian, ruffini, GTO = looking for sense of mvmt and vib
found in hand and larger jts
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Term
| Nociceptors (free nerve endings) |
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Definition
fast pain = A fibers
slow pain = C fibers
thermal, chemical and mechanical can stimulate |
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Term
Group I (IA and IB) = A alpha (A)-myelinated
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Definition
diameter = 12 - 20
conduction velocity = 60 - 120 m/sec
location = muscle spindle and GTO
most amount of MYELIN
associated with spinocerebellar pathway = unconscious proprioception |
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Term
| Group II = A beta (B)- myelinated |
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Definition
diameter = 6 - 12 microns
conduction velocity = 30 - 60 m/sec
location = mechanoreceptors and muscle spindle
associated = DCML |
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Term
| Group III = A delta (smallest myelinated) |
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Definition
diameter = 2 - 6 microns
conduction velocity = 10 - 30 m/sec
location = nociceptors A pain
amnt of myelin = LEAST
associated with = Lat spinothalamic tract |
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Term
| Group IV = C fibers unmyelinated |
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Definition
diameter = less than 1 micron
conduction velocity = 1 - 2 m/sec
location = nociceptors C fibers is pain
amnt of myelin = NONE
associated with = lat spinothalamic tract |
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Term
Ascending Pathway
dorsolateral systems
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Definition
| DCML and lat cervical system (spinocervical thalamic) |
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Term
Ascending pathway
antero lateral system |
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Definition
ant and lateral spinothalamic tracts
and spinoreticular and spinotectal tracts |
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Term
Ascending pathway
pathways to cerebellum |
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Definition
dorsal spinocerebellar
ventral spinocerebellar
cuneocerebellar
rostral spinocerebellar |
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Term
How many neurons does the ascending tract to take to get to the brain?
How many to the cerebellum? |
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Definition
3
2
afferent sensory fibers enter the SC through the dorsal root where brances can synapse in the SC or through a distinct pathway |
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Term
| General org of sensory systems |
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Definition
Usually first order = psuedounipolar located at DRG
2nd order = spinal cord or medulla
3rd order = VPL or thalamus
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Term
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Definition
discriminative touch and proprioception
light touch, tactile discrimination
two pt discrimination and steregnosis
conscious proprioception
static position sense, kinesthetic sense and vibration |
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Term
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Definition
| 1st order = from DRG enter SC, fibers usually large and myelinated (group IA, IB, II) travel up fasiculus gracilis from all levels and from above T6 fasiculus cuneatus |
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Term
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Definition
| 2nd order = travel in fas gracilis and cuneatus until closed medulla terminate on nucleus gracilis and cuneatus where fibers travel as internal arcuate fibers immediately cross midline at point of decussation of medial leminiscus |
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Term
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Definition
| 3rd order = at VPL of thalamus fibers project to somatosensory (primary and sensory) cortex via posterior limb of internal capsule |
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Term
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Definition
below medulla = ispi
above closed medulla(decussation) = contra
direct effects of lesion = loss of light touch, tactile discrimination, vib and proprioception
Indirect = coordination, dexterity and motor control
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Term
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Definition
pathway for pain and temperature
crude touch, itch, tickle and certain visceral sensations
pain and temp = lateral
crude touch = anterior
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Term
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Definition
1st order = neuron fibers enter SC in lateral bundles most are smaller, unmyelinated groups III and IV afferents cross in white matter (ant white commissure)
upon entering axons travel up two spinal seg ipsi via zone of lassiuer and terminate in substansia gelatinosa or nuclues propulsious
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Term
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Definition
| 2nd order = cross via ant white commissure and ascend to brainstem as ant and lateral spinothalamic tracts; in brainstem ALS terminates on VPL of thalamus |
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Term
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Definition
| 3rd order = from VPL of thalamus via posterior limb of interal capsule to the primary sensory cortex |
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Term
Spinothalamic tract
clinical lesions |
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Definition
lesion in SC = loss of pain and temp on CONTRA side
lesion in brainstem, thalamus or internal capsule = CONTRA would have to be initial isolated area to be IPSI 1st order |
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Term
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Definition
MCA = CONTRA if lesion of ant commissure = BILATERAL loss
PCA = thalamic pain syndrome |
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