Canonical Question
Neuro – Pathways
Master answer
Spinal Cord Tracts:
(not a comparison table)
Ascending Tracts
SENSORY
Descending Tracts
MOTOR
Convey sensory info from peripheral sensors to higher centres in brain.
From posterior to anterior:
Carry motor information
- Dorsal (posterior) column:
- fine touch + proprioception + vibration
- crosses at the brain stem
- Spinocerebellar tracts (ant + post):
- Carry proprioceptive info from muscles + joints to cerebellum
- Does not cross
- Lateral spinothalamic tracts
- pain + temperature
- Crosses within 2 vertebral segments
- Anterior spinothalamic tracts
- crude touch + pressure
- Crosses within 2 vertebral segments
- Corticospinal tracts (ant + lateral) “pyramidal tracts”:
- motor function – carry axons of UMN
- crosses at the brain stem
- Relay to alpha-motor neurons (LMN) in ventralnhorn of spinal cord
- Extrapyramidal tracts:
- rubrospinal, tectospinal, vestibulospinal, olivospinal, reticulospinal
- Originate in brainstem nuclei and do not pass through medullary pyramids
- Role in control of posture + muscle tone
John Craven
Anaesthesia & Intensive Care Medicine.
PAIN. VOLUME 12, ISSUE 1, P26-27, JANUARY 01, 2011
Acute hemi-section of the spinal cord at the upper thoracic level
Brown-sequard syndrome: Hemisection of the cord
| ipsilateral loss of motor function | below level of lesion | due to interruption of descending fibres in the lateral corticospinal [pyramidal] tracts. Initially the paralysis is flaccid, later it becomes hypertonic and hyperreflexic with extensor plantar response [upper motor neurone lesion]. |
| ipsilateral loss of light touch + proprioception + vibration | below level of lesion | due to interruption of ascending fibres in the posterior [dorsal] columns |
| contralateral loss of pain + temp | below level of lesion | Interruption of ascending fibres in the crossed lateral spinothalamic tract |
| ipsilateral loss of pain + temp | at the level of the lesion | segmental anaesthesia of the dermatome due to damage of the nerve roots and anterior horn cells at this level |
Exam appearances
| Exam | Exact wording | Relationship | Success |
|---|---|---|---|
| 2008B Q08 | Describe the clinical findings you would expect to see in a patient who underwent acute hemi-section of the spinal cord at the upper thoracic level. | historical_member | — |