Anatomy: Ascending and Descending Tracts Flashcards
what modality are ascending tracts?
sensory
two examples of ascending spinal tracts
- dorsal column/ medial lemniscus tract (DCLM)
2. spinothalamic tract (STT)
what does the DCLM tract sense?
fine touch and conscious proprioception
where do fibres cross from the DCLM tract?
medulla so right side of the brain controls left side of the body
where does the DCLM tract synapse?
thalamus and reaches the somatosensory cortex
two divisions of the DCLM tract
- cuneate fasciculus for upper body
2. gracile fasciculus for lower body
role of the STT
pain, temperature and deep pressure
where do fibres in the STT cross?
segmentally (ipsilateral control)
where does the STT synapse?
posterior horn of the spinal cord
what is the cortical motor homunculus?
parts of the body in the primary motor cortex
examples of descending tracts
- corticospinal tract (CST)
- corticobulbar tract (CBT)
- tectospinal tract
- rubrospinal tract
- reticulospinal tract
- vestibulospinal tract
what modality are descending tracts?
motor (arise from the motor cortex)
role of the corticospinal tract (CST)
controls fine movement
why is the CST a pyramidal tract?
tracts form visible ridges referred to as pyramids on anterior surface of the medulla
two parts of the CST
- lateral CST (pyramidal decussation) = limbs and digits
2. anterior/ ventral CST (segmental decussation) = trunk and posture
which side of the body does the CST supply?
contralateral side
what does the corticobulbar tract control?
muscles of face, head and neck
what does the corticobulbar tract innervate?
bilateral innervation of cranial nuclei except CNXII and lower part of CNVII
what does an UMN lesion of CNVII have?
forehead sparing
what does a LMN lesion of CNVII have?
forehead involvement too
four example of extrapyramidal motor tracts
- tectospinal tract
- rubrospinal tract
- reticulospinal tract
- vestibulospinal tract
role of tectospinal tract
mediates head and neck movement to visual stimuli
where does the rubrospinal tract arise from?
red nucleus of the midbrain
role of the rubrospinal tract
excites flexors and inhibits extensors of the upper body
location of the reticulospinal tract
central core of the brainstem
role of the reticulospinal tract
excites extensors
role of the vestibulospinal tract
input to anti-gravity extensor muscles
