Spinal Tracts Flashcards
Explain Spinothalamic tract
Ascending sensory tract
Conveys pain, temperature, and crude touch.
Likely at least partially responsible for itch (and probably tickle) sensations, pressure sensations from bladder and bowel, and sexual sensations.
Decussation occurs at spinal cord level.
Projects to the primary somatosensory cortex in brain.
Can be divided into:
Lateral spinothalamic tract
Pain and temperature
Anterior spinothalamic tract
Crude touch and firm pressure.
Explain what Ascending and Descending tracts are.
Ascending tracts – Sensory information from peripheral sensory receptors is conducted through a series of neurons that synapse with targets in the spinal cord, cerebral cortex, and other brain structures. The sensory modalities carried in these pathways include pain, temperature, tactile, and proprioceptive input
Descending tracts – Motor information – voluntary movements; postural movements; and coordination of head, neck, and eye movements. These pathways originate from the cerebral cortex and brainstem and are influenced by sensory input and feedback circuitry from the cerebellum and basal ganglia.
Tracts are generally within the white matter however nuerons can be within the grey matter.
Are tracts on one side or both sides?
Both sides
Explain the Posterior/dorsal column–medial lemniscal pathway (PCML/DCML)
Ascending sensory tract
Conveys conscious proprioception (body position), vibration, fine touch, and discriminative touch (e.g. two-point discrimination).
Decussation occurs in the medulla as medial lemniscus.
Projects to the primary somatosensory cortex in the brain.
If there was a tumour within the medial lemniscus then you would have less sensitivity to vibration etc.
Explain the Corticospinal tract
Descending motor tract
Responsible for voluntary movement.
Can be divided into:
- Lateral corticospinal tract
Originates in the primary motor cortex
Responsible for movement of contralateral limbs
Decussates at medulla in pyramids - Anterior/ventral corticospinal tract
Originates from primary motor cortex and supplementary motor area
Responsible for movement of trunk, shoulder, and neck muscles.
Does not decussate, continues to ipsilateral side.
What is the corticospinal tract responsible for ?
VOLUNTARY MOVEMENT
What is the Posterior/dorsal column–medial lemniscal pathway (PCML/DCML) responsible for ?
Conveys conscious proprioception (body position), vibration, fine touch, and discriminative touch (e.g. two-point discrimination).
Explain the rubrospinal tract
Descending motor tract
Responsible for involuntary movement – Movement regulation – flexion muscles and inhibiting extensor tone as well as fine motor control.
Originates in red nucleus in midbrain.
Decussates in midbrain as ventral tegmental decussation.
Explain the tectospinal colliculospinal tract
Tectospinal/colliculospinal tract
Descending motor tract
Responsible for modulating reflex postural movements in response to visual stimuli – i.e. coordinates head and eye movements.
Originates in dorsal midbrain.
Decussates in midbrain as dorsal tegmental decussation.
What is the Tectospinal/colliculospinal tract resposible for ?
HEAD AND EYE MOVEMENT
Explain Vestibulospinal tract
Descending motor tract
Facilitates activity of extensor/antigravity muscles and inhibits activity of flexor muscles to maintain balance and an upright posture.
Can be divided into:
Lateral vestibulospinal tract
Originates in pons
Does not decussate
Medial vestibulospinal tract
Originates from medulla
Does not decussate
Explain the reticulospinal tract
++ we don’t know the pathway of this too well.
Reticulospinal tract (not shown)
Descending motor tract
Not anatomically well defined.
Example of functions are regulating voluntary movements in reflex activity and automatic posture and gait-related movements.
Originates in pons and medulla.
