Long Ascending Tracts

Question 1

The fasciculus gracilis is located ____

Answer 1

Medially

Question 2

The fasciculus cuneatus is located ___

Answer 2

Laterally

Question 3

Neurons located in dorsal root ganglion represent

Answer 3

First order neurons (neuron I)

Question 4

Peripheral processes of First order neurons innervate

Answer 4

Pacinian corpuscle (sensing tactile and vibration stimuli) and Meisnner’s corpuscle (sensing touch)
Also propioceptors involved in kinesthesia

Question 5

How do the first order neurons central processes ascend

Answer 5

Ipsilaterally

Question 6

Where do first order neurons end

Answer 6

They terminate at second order neurons in the ipsilateral nucleus gracilis in the medulla

Question 7

How do axons of second order neurons travel

Answer 7

Ventromedially as internal arcuate fibers and cross midline to form medial lemniscus

Question 8

Crossed tract that ascend through medulla, pons, and midbrain and terminates in third order neurons

Answer 8

Medial lemniscus

Question 9

Location of third order neurons

Answer 9

Contralateral ventral posterolateral nucleus of the thalamus

Question 10

Where does third order nucleus end

Answer 10

Terminates in medial aspect of sensorimotor cortex

Question 11

Fasciculus gracilis is involved in mediating

Answer 11

Conscious proporception, kinesthesia, and discriminative touch

Question 12

Where does fasciculus cuneatus appear

Answer 12

Thoracic segments above T6 (T1-T6)

Question 13

Second order nucleus location (fasciculus cuneatus)

Answer 13

Ipsilateral Nucleus cuneatus of medulla

Question 14

Different names for dorsal column pathways (gracilis and cuneatus)

Answer 14

Dorsal column or medial lemniscus

Question 15

Damage to dorsal column/ medial lemniscus

Answer 15

Symptoms appear ipsilateral to affected dorsal column in dermatome so AT AND BELOW the level of spinal cord lesion

Question 16

Symptoms of damage to dorsal column

Answer 16

Loss of tactile sense, kinesthetic sense,
Cervical lesion- can’t identify object placed in hand ipsilateral to lesion
Lumbar lesion- ipsilateral lower limbs, poorly coordinated movements (clumsy)

Question 17

Innervates mainly muscle and tendon where central processes project to nucleus dorsalis of Clarke that ascend ipsilaterally, reach inferior cerebellar peduncle in medulla and terminate in cerebellar vermis of the anterior lobe.
(NON CONSCIOUS PROPIOCEPTION) LOWER LIMBS*

Answer 17

Dorsal spinocerebellar tract

Question 18

Damage to dorsal spinocerebellar tract

Answer 18

Loss of non conscious proprioception and coordination ipsilateral to lesion

Question 19

Absence of nucleus dorsalis of Clarke and is rostral to C8. Afferent fibers of this tact ascend ipsilateral in fasciculus cuneatus and project to neurons of accessory cuneate nucleus of the lower medulla. Related to UPPER LIMB non conscious proprioception and this tract ends in cerebellar cortex

Answer 19

Cuenocerebellar Tract

Question 20

The axons of the second order neurons in this tract cross in the spinal cord and ascend through medulla to pons crossing again when it joins the superior cerebellar peduncle and termimates in the Vermal región of the anterior lobe of the cerebellum

Answer 20

Ventral (Anterior) Spinothalamic Tract

Question 21

Conveys information about whole limb movements and postures to the cerebellum. Lesion causes loss of non conscious proprioception and coordination in lower limbs

Answer 21

Ventral spinothalamic tract

Question 22

Similar course of ventral spinothalamic tract but afferents are from golgi tendon organs located in upper limb, tract is uncrossed, and it enters cerebellum via inferior cerebellar peduncle

Answer 22

Rostral spinothalamic tract

Question 23

Damage to rostral spinothalamic tract causes

Answer 23

Loss of non conscious proprioception and coordination in the upper limb

Question 24

Transmission of pain and temp sensations that ascend in ventrolateral quadrant of spinal cord located contralateral to the side where afferents carrying these sensations enter the spinal cord

Answer 24

Spinothalamic tract

Question 25

Spinothalamic tract pathways

Answer 25

Direct pathway: neospinothalamic tract mediates pain and temp and simple tactile sensations
Indirect pathways: paleospinalthalamic, spinorecticular, and spinomesencefalic tracts that mediate effective and arousal components of these sensations