Dorsal Colum Tracts Flashcards
What is the function of dorsal column tracts
Carries propriiception
What is the beginning and position of dorsal root
The are formed by central processes of pseudounipolar dorsal root ganglia cells
They enter the spinal cord via dorsal root
The occupy the posterior white column
The gracile tract lies medially and the cuneate tract lies laterally above T6
What is the lamination and termination of dorsal root ganglion
Lamination :
In the dorsal column
The sacral and cooccygeal fibers lie most medially and the cervical fibers lie most laterally
Termination:
The gracile and cuneate fibers ascend in the spinal cord to reach the medulla and end in gracile and cuneate nuclei of the medulla
While they ascend they give collateral branches that end on dorsal horn of spinal cord
What are the sensation carried by dorsal column tracts
1-fine touch
2-proprioception
3-vibration
4-deep pressure
5-stereognosis
Explain the pathway of first order neurons of dorsal column tracts
Their peripheral processes carry sensations from deep receptors
Their central processes pass to spinal cord via the dorsal root
Fibers from the lower body ascend medially in the dorsal column forming the gracile tract
Fibers from the lower part of the body ascend laterally forming the cuneate tract
Explain the pathway of second order neurons
Cuneate and gracile nuclei
The axon of these nuclei pass the median plans forming the internal arcuate fibers (sensory decussation)
Fibers ascend in the brain stem forming the medial leminiscus to reach the thalamus
Explain the third order neurons of dorsal column tracts
Ventral postrolateral nucleus of the thalamus
Axons if theses cells pass through posterior limb of internal capsule then in corona radiate to reach the sensory area of cerebral cortex
What is the function of short ascending tracts
Carries unconscious proprioception
Explain the posterior spinocerbellar pathway
Carries proprioception from lower limb and trunk
Explain the posterior spinocerebellar tract
The central processes of the cells of DRG enter the spinal cord via the dorsal root
It ascends ipsilaterally in the lateral white column posterior to the anterior spinocerebellar tract enter the ipsilateral cerebellum via the posterior cerebellar peduncle
Explain the pathway of anterior spinocerebellar tract
Carries proprioception from the lower limb
The central processes of the cells of DRG enter the spinal cord via the dorsal root to end on Clarke’s cells
Axons forming the tract mostly decussate but some remain ipsilateral
The enter the cerebellum via the superior cerebellar peduncle and then criss again to reach the ipsilateral cerebellum
Explain the pathway of the spinoolivary tract
It carries proprioception from upper and lower limb
It’s fibers cross and ascend at the junction between lateral and anterior white column to end on the contralateral olivary nucleus
They cross and pass via ICP to reach the ipsilateral cerebellum
Explain the pathway of collaterals if the cuneate tracts
Carries proprioception from the upper limb to the accessory cuneate nuclei
Axons of the accessory cuneate nucleus form the external arcuate fibers which reach the ipsilateral cerebellum via the ICP
