Tracts Flashcards
What is white matter
Mixture of nerve fibre, neuroglia, blood vessels
White colour - myelination
What is white matter divided into
Anterior white column/funicuius
Lateral white column
Posterior white column
Anterior white commissure
Ascending sensory pathway
1st order -
Cell body in dorsal root ganglion
2nd order -
Axon crosses, ascends, terminates in thalamus
3rd order -
To cerebral cortex
Ascending tract definition
Neural pathway by which SENSORY information from peripheral nerves is transmitted to the cerebral cortex
Ascending tract to the CEREBRUM
Posterior column/medial lemniscal pathway
Spinothalamic tracts
Ascending tract to the CEREBELLUM
Spinocerebellar tracts - anterior and posterior
Cuneocerebellar tract
Ascending tract to the BRAINSTEM
Spinoreticular
Spinotectal
Spino-olivary
Posterior column / medial lemniscal
Function & the 2 pathways:
Modality - conscious proprioception, vibratory sense, fine touch / discriminative touch
Fasciculus Gracilis
- lower limbs & lower trunk (T6 down)
Fasciculus Cuneatus
- upper limbs & upper trunk
Posterior column / medial lemniscal pathway
Order neurons
1st order neuron = dorsal root ganglion
- Fasciculus Gracilis
- Fasciculus Cuneatus
2nd order neuron = medulla oblongata
- Nucleus gracilis
- Nucleus cuneatus
3rd order neuron = thalamus
Lateral spinothalamic tract
Describe the 2 types of pain
FAST PAIN
A 𝛿 fibres
Myelinated
Localised
Fast conducting
Glutamate
SLOW PAIN
C fibres
Unmyelinated
Poorly localised
Slow conducting
Substance P
Ipsilateral
Same side (problem on same side of spinal cord as the body)
Contra lateral
Opposite side (crossing over in spinal cord)
Posterior column / medial lemniscal pathway
Modality & receptors
Modality – Conscious proprioception, vibratory sense, fine touch/ discriminative touch
Receptors – Meissner’s corpuscle, Pacinian corpuscle, muscle spindle and Golgi tendon organ
Lateral spinothalamic tract
Modality & receptors
Modality - pain & temperature
Receptors - free nerve endings, nociceptors
Lateral spinothalamic tract
Order neurones
1st order = dorsal root ganglion
2nd order = substantia gelatinosa (cross over)
3rd order = thalamus (ventroposterior lateral nucleus)
Anterior spinothalamic tract
Modality & receptors
Modality - light (crude) touch & pressure
Receptors - free nerve endings
Anterior spinothalamic tract
Order neurones
1st order = dorsal root ganglion
2nd order = substantia gelatinosa
3rd order = ventroposterior lateral nucleus of thalamus
Posterior spinocerebellar tract
Modality, function & receptors
Modality = unconscious proprioception
Function = fine coordination of posture & movement of trunk & lower limb
Receptors = muscle spindles, Golgi tendon organs, joint receptors of trunk & lower limb
Posterior spincerebellar tract
Order neurones
1st order = dorsal root ganglia
2nd order = lateral funiculus > medulla oblongata . Inferior cerebellar peduncle
3rd order = cerebellum
Anterior spinocerebellar tract
Modality, function & receptors
Modality = unconscious proprioception
Function = gross coordination of posture & movements of trunk & lower limbs
Receptors = muscle spindles, Golgi tendon organs & joint receptors of trunk & lower limbs
Anterior spinocerebellar tract
Order neurones
1st order = dorsal root ganglia
2nd order = contralateral lateral funiculus > medulla oblongata, pons, midbrain > superior cerebellar peduncle
3rd order = cerebellum
Decending tracts
Carry motor information
Pyramidal tract
Corticospinal tract (lateral & anterior)
Extrapyramidal tracts
Rubrospinal - facilitates flexor & inhibits extensor muscles (crosses in superior colliculus of midbrain)
Reticulospinal - locomotion & postural control (uncrossed)
Vestibulospinal - facilitates extensors to maintain posture/balance & inhibits flexors (uncrossed)
Tectospinal - reflex postural movements in response to visual stimuli (crosses in superior colliculus of midbrain)
Olivospinal - reflex movements arising from proprioceptors (crosses in lateral white column)
What are the 3 neuron pathways
1st order neuron - cerebral cortex (UMN)
2nd order neuron - internuncial neuron in the anterior grey column
3rd order neuron - motor neurons in the anterior grey column of spinal cord (LMN)
Clinical significance of descending tracts
Amyotrophic lateral sclerosis (motor neuron disease)
