Ascending/Descending Spinal Tracts Flashcards
Sensory homunculus
Medial - lower limb
Dorsolateral - upper limb
Lateral - face
DCML
Vibratory, fine touch, proprioception
Dorsal column medial lemniscus pathway
Fasculus gracilis and cuneatus
Cervical vs lumbar levels of DCML
Columnar shape in cervical
Fasciculus gracilis and cuneatus
Gracilis is at all levels
Cuneatus is only at cervical and is more lateral
1st order
2nd order
3rd order neurons of DCML
1st - located in spinal ganglia of spinal cord between (T7-Co1 for gracilis and C1-T6 for cuneatus) and project into ipsilateral nucleus gracilis of cauda medualla
Second - project to contralateral ventral posterior lateral nucleus (VPL) of the thalamus…crossing fibers are arcuate fibers/medial lemniscus
3rd - go to postcentral gyrus of parietal lobe via internal capsule
Posterior cord syndrome just the gracilis
If injury to the gracilis, then get ipsilateral loss of vibration, dsicrimitive touch, and proprioception
Posterior cord syndrome both cunaeuts and gracilis
Ipsilateral loss of vibratory, fine touch, and proprioception to both upper and lower body
Spinothalamic pathway and organzation
Nociceptive and temp for all of body but head
All spinal cord levels
Made of lateral and anterior tract
More caudal is morelateral
1st
2nd
3rd order
Spinothalamic pathway
1st - central processes in the dorsal root entry zone and may synapse in lamina 1,2,or 5
2nd - neurons from lamina 1 or 5 cross contralateral by anterior white commisure and terminate on VPL
3rd - from VPL to the primary sensory cortex
Anterior spinothalamic pathway
Concerned with conveying crude touch
Spinothalamic tracts also communicate with
REticular formation
Brown-Sequard ysndrome only sensory
Lesion of the entire right side of the spinal cord
At the lesion - total loss of sensory on ipsilateral
Ipsilateral loss of vibration, proprioception, and fine touch beow
Contralateral loss of pain and temp below (1 or 2 below)
Central cord syndrome
Cyst or caivty in spinal cord creates a lesion of the anterior commissure expanding 1-2 segments resulting in bilateral loss of pian and temp at level of lesion
Posterior spinocerebellar pathway
Conveys proprioception and fine touch to lower limb and trunk
1st
2nd neurons for posterior spinocerebellar pathway
First - terminate in dorsal nucleus of clarke
2nd - remain ipsilateral and enter cerebellum by way of inferior cerebellar peduncle (medulla) and terminate in cerebellar cortex
Anterior spinocerebellar trat
For whole limnb movements
Anterior spinocerebellar 1st and 2nd
1st - central enter between T12 and S2 and terminate on spinal border neurons of ventral horn
2nd - cross at white commissure and enterr via the superior cerebellar peduncle
Cuenocerebellar pathway
Equivalent to the posterior spinocerebellar tract (for upper limb and superior trunk)
Cuenocerebelar tract 1st and 2nd
1st - ascend in the fasciculus cuneatus and terminate in accessory cuneate nucleus
2nd - ascend through inferior cerebellar peduncle to ipsilateral cerebellar cortex
Lower motor neuron lesion signs
Ipsilateral to lesion
Flaccid paralysis
Hyporeflexia
Muscle atrophy
Muscle fasciculation early in course of the lesion
Corticospinal tract names
Subcortical - corona radiata and internal cpasule
Midbrain - cerebral peduncles
Pons - corticospinal fibers
Medulla - pyramids
Spinal cord - lateral or medial corticospianl tract
Corticospinal path crossiover
Through pyramidal decussation in the caudal medulla
Lateral corticospinal tract
Descends in posterior portion of lateral funiculus and terminates on interneurons and somatomotor neurons in the ventral horn of the spinal cord
Anterior corticospinal tract
These terminate on the medial portion of the anteriro horn (trunk muscles)
Corticospianl organization
Cervical spinal cord fibers medial while sacral are more lateral
Upper motor neuron lesions
Little atrophy
Spastic paralysis
Hyper reflexia
Extensor plantar sign
Brown-sequard syndrome motor
Damage to anterior grey matter causes ipsilateral LMN signs AT the level
Damage to lateral corticospinal tracts causes ipsilateral UMN signs BELOW the level of the lesion
Lateral vestibulospianl tract
Extensory muscles associated with axial region and lower limb for positioning
Medial vestibulospinal tract
Cervical and upper thoracic levels of the spinal cord
Helps control head positioning
Tectospinal tract
Moves head and neck in position to visualize an object
Reticulospinal tracts
Activate an extensor reflex
Rubrospinal tract
Red nucleus in the rostral midbrain…faciliates flexor muscles and inhibits extensor muscles
Postures
Decorticate - patient is stiff iwth arms bent toward the body…above the red nucleus lesion
Decerebrate posture - lesion at or below the level of the red nucleus meaning rubrospianl tract is pborken
