dorsal column medial leminiscal pathway Flashcards
what is this pathway important for
discriminative touch
what is included in discriminative touch
- fine, two point touch
- pressure and stretch of the skin
- vibrations
- proprioreception
what is proprioception
knowing ones position of joints and muscles in space
cerebellum and CNS needs to be aware of this
what is a tract
a bundle of axons in the central nervous system
is the dorsal column medial leminiscal pathway acscending or descending
ascending
what are meissners corpuscles
found in dermal papillae
pick up fine touch
what are merkels discs
found in stratum basal of the epidermis
specific receptors pick up superficial pressure and very fine touch
what do pacinian corpuscles detect
pressure and vibration
found in dermis and hypodermis
what are the peritrichial nerve endings
nerve fibres wrapped around hair follicles that detect the movement of the hairs
what do ruffini corpuscles detect
stretch of the skin and vibrations
what are the two fibres important for proprioception
extrafusasl and intrafusal
wha are extrafusal fibres
these are the contracting fibres of the skeletal muscle, they are chain fibres and react to the onset of stretch
what are intrafusal fibres
these detect stretch and will respond to the progression of stretch
what are the proprioceptive fibres of the body
extrafusal and intrafusal fibres of skeletal muscle
what are muscle spindles
type 1a fibres, proprioceptive
describe golgi tendon organs
receptors that pick up tendon stretching like when muscles are contracting
if the tendon is pulled on too much, there is a protective response because of these receptors
carried on 1b fibres
what pain comes from a delta fibres
fast pain and crude touch
what do a alpha fibres get stimulation from
muscle spindles and golgi tendon organs
what do a beta fibres take stimulation from
receptors in the skin
how fast is a alpha axons
120 metres a second
how fast are a delta fibres
30 metres a second
what type of stimulation is a beta
pressure touch and vibration
how do fibres enter the spinal cord
they come in through the first order neuron located in the dorsal root ganglion
they funnel in
information for the lower half of the body enters the spinal cord at which vertebral level
T6 or below
what is a ganglion
a group of cell bodies in the peripheral nervous system
describe somatotopic arrangement of the spinal cord
the medial region has the fibres from the lowest region, and as you move out more laterally the fibres go from sacral to lumbar to thoracic, and then certical is on the very outer portion
where are second order neurons found
brainstem, at the medulla
what are the fibres called when the second order neurons cross over in the brainstem
the internal arcuate fibres
