Spinal cord Flashcards
where is the dorsal/ posterior column and carries info from
it is found in the dorsal white matter, it carries information from- skin receptors, joint and muscle receptors (position sense), to the cortex
motor descending (efferent) tracts
pyramidal tracts- lateral/anterior corticospinal tract
extrapyramidal tract- rubrospinal, reticulospinal, olivospinal, vestibulospinal tracts
sensory and ascending (afferent) pathways
dorsal column medial lemniscus system, spinocerebellar tracts- anterior and posterior, anterolateral system- anterior and lateral spinothalamic tract
2 sections of dorsal/ posterior colum
gracilis and cuneatus
first order neuron- dorsal/ posterior column
this brings the signal from a receptor. the upper limb and upper chest use cuneatus and the lower limbs and trunk use gracilis
second order neuron- dorsal/ posterior column
depending on the tract the first order neurone will synapse with a second order neuron at the gracile nucleus and the cuneate nucleus and the second order neuron crosses contralaterally @ the medulla and travels to thalamus
third order neuron- dorsal/ posterior column
the second order neuron synapses with a third order neuron at the thalamus and the third order neurone travels to the primary somatosensory cortex
spinothalamic tract
the tract runs from the spinal cord to the thalamus and then send signals to the cortex
spinothalamic tract- 2 sections
lateral spinothalamic tract- carries pain and temperature sensation, anterior-spinothalamic tract- itch, tickle, pressure, vibrations, and crude, poorly localized touch sensation
spinothalamic tract- first order neuron
a first order motor neuron brings the signal from a receptor, this is different as it synapses straight away and crosses at this level
spinothalamic tract- second order neurone
this synapses with the first order neuron at the level of entry into the spinal cord. the second order neuron crosses to the opposite side of the spinal cord and then ascends to the thalamus
spinothalamic tract- third order neurone
the second order neuron synapses with a third order neuron at the thalamus and this then travels to the primary somatosensory cortex
spinocerebellar tract-
this tract runs from the spinal cord to the cerebellum. made up of 2 sections- posterior spinocerebellar tract, anterior spinocerebellar tract
spinocerebellar tract- posterior spinocerebellar tract
this is an uncrossed tract (i.e. the fibres rises ipsilaterally) and enter the cerebellum via the inferior cerebellar peduncle
it does not cross at all and carries information at the same side
spinocerebellar tract- anterior spino-cerebellar tract
this is a tract in which most fibres cross the spinal cord at entry level and then crosses back just before entering the cerebellum via the superior cerebellar peduncle. those fibres that do not cross at the level of entry to the spinal cord rise ipsilaterally and enter the cerebellum via the superior cerebellar peduncle
what is the corticospinal tract
this tract originates at the cortex and then travels down directly to the spinal cord. the 2 sections- the lateral corticospinal tract, and the anterior corticospinal tract
this tract originates at the motor and premotor areas of the cortex (cell bodies are in the cortex and the axon travels down the spinal cord.
corticospinal tract- the lateral corticospinal tract
this carries information essential for control of the extremities
corticospinal tract- anterior corticospinal tract
this carries information essential for control of axial skeleton
corticospinal tract- axon
the axon descends ipsilaterally via the cerebral peduncle and coverage into axon bundles (which a pyramidal in shape hence the name pyramidal tract) at the medulla oblongata
corticospinal tract- what happens at the medulla oblongata
2 segments: 80-90% of the fibres cross to the contralateral side and descend as the lateral corticospinal tract to the respective level of spinal cord, the remaining 10-20% descend as the anterior corticospinal tract and then cross over at their respective level of spinal cord
what is the reticulospinal tract
this indirect originates at the reticular formation and travels down to the spinal cord. there are 2 descending tracts lateral/ medial reticulo- spinal tract, it is difficult to identify a clearly demarcated pathway
what do the medial/ lateral reticulospinal tract
LRT- facilitate the flexor reflexes and inhibits extensor reflexes and the MRT does the opposite
what is the vestibulospinal tract
the tract originates at the lateral vestibular nucleus and ends at the spinal cord. the integration between the head and neck, the axial skeleton and the extremities is probably controlled by activity in this tract
vestibulospinal tract- uncrossed tract
this is also an uncrossed tract (i.e. descends ipsilaterally). this tract helps coordinate the activity between the head and neck and the rest of the muscles in the axial skeleton and the limbs. the nerves in the tract are also essential for the modulation of reflex activities and balance
what is the rubrospinal tract
the tract originates at the red nucleus (in brainstem) and ends at the spinal cord and is supposed to help with fine control of movement. it is not clear if this tract plays a significant role in humans. it is one of the fastest conducting neurones @120m/s
rubrospinal tract- crossed
this is a crossed tract that crosses over at the origin (i.e. descends contralaterally), this tract could also provide the potential for indirect control of movements
what is the spinal cord vital for
the spinal cord is vital for conveying and integrating sensory and motor information to and from the periphery
what is a spinal cord lesion
a spinal cord lesion may impair motor, sensory, autonomic functions on size of damage, traumatic lesion- 84%
example of non- traumatic lesions
degenerative disc diseases and spinal canal stenosis, spinal infracts, tumour, inflammation of spinal cord, viral infection, developmental/ congenital abnormalities
what is a complete spinal cord lesion
a complete loss of function below the point of injury and outcome more predictable
what is an incomplete spinal cord lesion
some spraining of neutral activity below the level of lesion, incomplete lesions are more common 55-65%, outcomes less predictable
what are the vulnerable areas of the vertebral column
cervical spine (C5-C7)- 55% of all spinal cord injuries, thoracolumbar, typically T12, mid thoracic T4-7, majority of traumatic cases= fracture dislocation
what is tetraplegia
this is impairment or loss of motor control and/ or sensory function is cervical segments of the cord- tetraplegia affects all 4 limbs
what is paraplegia
this is impairment or loss of motor control and/ or sensory function in thoracic, lumbar or sacral segments of the cord- depending on level of injury, trunk and legs and pelvis may be involved
