Spinal tracts/ Muscle fibres Flashcards
what type of info do ascending pathways carry?
sensory
how many orders does the ascending pathway have
4
what does DCML carry
fine touch, vibration, proprioception
what r the two parts of the DCML and what do they relate sensory info for
fasciculus cuneate- upper limb
fasciculus gracilis- lower limb
what r the two parts of the spinothalamic tract and what type of sensory information do they carry
anterior= crude touch and pressure lateral= pain and temp
what does spinocerebellar carry
unconscious proprioceptive information from muscle to cerebellum
what type of info do descending pathways carry?
motor
how many orders of neurons does the descending pathway have
2
what r the 2 classification of descending tracts
pyramidal and extrapyramidal
what do pyramidal tracts carry
voluntary control of muscle
what do extrapyramidal tracts carry
involuntary/ autonomic control of musculature
what re the two pyramidal tracts and what do they carry
corticospinal- results of body muscles
corticobulbar- head and neck muscles
what r the 4 extrapyramidal tracts
vestibulospinal
reticulospinal
rubrospinal
tectospinal
what is the path fo the DCML
- respective fasciculus bring info up to reach the dorsal root ganglia and ascend ipsilaterally
- decussate at medulla
- ascends to contralateral thalamus to go to contralateral somatosensory cortex
what is the path fo the spinothalamic
- reaches dorsal root ganglion from receptors in periphery
- decussation 1/2 levels above ventral horn
- ascends to contralateral thalamus to go to contralateral somatosensory cortex
what does vestibulospinal tract carry and where does it come from
balance and posture
vestibular (8th) nucleus
what does reticulospinal tract carry and where does it originate from
muscle tone and voluntary movement
pons
what does tectospinal tract carry and where does it originate from
movment of head in relation to vision
superior colliculus
what does rubrospinal tract carry and where does it originate from
fine control of hand movement
red nucleus
what r the 2 extrapyramidal tracts that decussate
rubrospinal and tectospinal
path of corticospinal tract
- ascends though corona radiata to the internal capsule
- 85% decussates at medulla and goes contralateral and 15% remains ipsilateral
- terminates at the ventrolateral horn of the spinal cord and synapses onto 2 order neurons
path of corticobulbar tract
- corona radiata to internal capsule to crus cerebri, pons and medulla
- synapse at cranial nerve nuclei to supply head and neck muscles
5 stages of neurotransmitter cycle at NM junction
- manufacture
- storage
- release
- interaction (NT with post synaptic receptors)
- inactivation (of NT)
compare bells palsy to stroke (UMN/LMN, what order neurone, where is teh lesion)
bells= LMN affected, 2nd order neurones, CN 7 lesion stroke= UMN affected, 1st order neuorons, UMN lesion
what is a motor unit
alpha motor neurone and the extrafusal skeletal muscle it innervates
function of alpha motor neurons
voluntary muscle contraction
function of gamma motor neurons
controls muscle contraction in response to external forces acting on muscles
what does a smaller motor unit mean
fine regulation/ control
what muscle is controlled by lateral and medial alpha motor neurones
lateral- distal muscle
medial- proximal
what r the two things intrafusal muscles fibres sense and for what reason
sense stretch and monitors muscle length and rate of change to prevent overstretching of muscles
types of intrafusal muscle fibres and functions (2)
1a- excites alpha motor neurones
2- inhibits alpha motor neurones
what do golgi tendons detect and what type of sensory fibres do they have and what is its function
tension
1B
if too much tension, golgi tendon inhibits muscle from contracting
what is a muscle spindle made of and what does it detect
intrafusal fibres and stretch receptors
stretch
efferent and afferent supply of muscle spindle
efferent= gamma afferent= 1a (fast), 2 (slow)
types of pain and what tract carries them and what fibres is this
slow pain- anterior spinothalamic C fibres
fast pain- lateral spinothalamic alpha fibres
what is the neurotransmitter for fast acting pain, where does it act and what fibre is this
glutamate
at 1st and 2nd order neurones
alpha fibres
what is the neurotransmitter for slow acting pain and what fibre is this
glutamate AND substance p
C fibres
what does substance p do and how
gives nociception (dull achy pain) by binding for longer
analgesic vs anaesthetics
analgesic- selective pain suppression, consciousness not affected
anaesthetics- total pain suppression, consciousness can be affected
ascending pathway for PAIN
- nociceptors sense pain
- trasnmit impulse to DRG via alpha or c fibres
- decussation 1-2 spinal levels above where alpha becomes lateral and c fibres become anterior
- go to thalamus to the somatosensory cortex
compare alpha and c fibres
alpha= unmyelinated c= myelinated
what is pain gate and what is the effect of this
small descending pathways that inhibit interneurones of the spinothalamic tract
prevent impulses reaching the somatosensory cortex
which 3 tracts decussate at the medulla
DCML
corticobulbar
corticospinal
what is end plate potential adn how is the AP propagated
like at a NM junction but stronger depolorisation
propagated to all adjacent fibres in an alpha motor unit
compare UMN and LMN lesion location
UMN= between motor cortex and the spinal cord LMN= between spinal cord and muscle
compare UMN and LMN lesion damage symtoms
UMN= hypertonia, spasticity (hyperactive kid) LMN= hypotonia, muscle atrophy (slow grandad)
what is conus medularis and what level does this occur
where the spinal cord becomes tapered
L1/2
what is cauda equina
nerves from lumbar and sacral nerves handing obliquely downwards
what is the filum terminale and what does it contain
fibrous strand extending from conus medullaris to coccyx
curves of the vertebral column name and direction
cervical and lumbar curve anterior
thoracic and sacral curve posterior
