P1 - Tracts

Question 1

Function of Dorsal Column Medial Lemniscus (DCML)

Answer 1

sensory information for fine touch, proprioception, and vibration

Question 2

Fasciculus Gracilis

Answer 2

carries sensory information for fine touch, proprioception, and vibration from lower limb

located more medially in SC

Question 3

Fasciculus Cuneatus

Answer 3

carries sensory information for fine touch, proprioception, and virbation from upper limb

located more laterally in SC

Question 4

Pathway of DCML

Answer 4

• originates in peripheral receptors of UE/LE and travels through fasciculus gracilis/cuneatus to synapse w/ gracile/cuneate nuclei in medulla
• decussates in medulla to contralateral side, then synapses w/ ventral posterolateral nucleus in thalamus
• travels from thalamus to primary somatosensory cortex in postcentral gyrus

Question 5

DCML Decussation

Answer 5

yes - in the medulla

Question 6

Function of Anterolateral Spinothalamic Tract

Answer 6

• anterior: sensory information for crude touch and pressure
• lateral: sensory information for pain and temperature

Question 7

Pathway of Anterolateral Spinothalamic Tract

Answer 7

• originates in UE/LE receptors to dorsal root ganglion, where it synapses in dorsal horn of SC
• decussates immediately (w/in 1-2 segments) through anterior commissure of SC to contralateral side and continues traveling up the SC to synapse w/ ventral posterolateral nucleus in thalamus
• travels from thalamus to primary + secondary somatosensory cortices through internal capsule

Question 8

Anterolateral Spinothalamic Decussation

Answer 8

yes - through anterior commissure at SC level (or w/in 1-2 segments) it enters

Question 9

Function of Posterior Spinocerebellar Tract

Answer 9

carries proprioceptive information from lower limbs and trunk to cerebellum for coordination of movement and balance

Question 10

Pathway of Posterior Spinocerebellar Tract

Answer 10

• originates in receptors in LE and synapses w/ Clark’s nucleus in dorsal horn of SC
• travels ipsilaterally to inferior cerebellar peduncle in cerebellum

Question 11

Posterior Spinocerebellar Tract Decussation

Answer 11

does NOT decussate

Question 12

Function of Anterior Spinocerebellar Tract

Answer 12

carries proprioceptive information from lower limbs to cerebellum

Question 13

Anterior Spinocerebellar Tract Pathway

Answer 13

• originates in receptors in LE and synapses in dorsal horn of SC
• decussates immediately at SC level of entry to ascend contralaterally to midbrain
• at the superior cerebellar peduncle, some fibers will cross again (back to ipsilateral), while others remain contralateral
• all fibers synapse in cerebellum

Question 14

Anterior Spinocerebellar Decussation

Answer 14

yes - 2 times
- all fibers decussate at SC level of entry
- in the cerebellum, some fibers will decussate again to return to the ipsilateral side

Question 15

Function of Cuneocerebellar Tract

Answer 15

carries proprioceptive information from upper limbs and neck to cerebellum for coordination of movement

Question 16

Cuneocerebellar Tract Pathway

Answer 16

• originates in receptors of UE and neck and ascends to synapse w/ lateral cuneate nucleus in medulla
• continues to travel ipsilaterally and synapse in cerebellum via inferior cerebellar peduncle

Question 17

Cuneocerebellar Tract Decussation

Answer 17

does NOT decussate

Question 18

Function of Rostrospinocerebellar Tract

Answer 18

carries proprioceptive information from upper body to cerebellum for coordination and motor control

Question 19

Rostrospinocerebellar Tract Pathway

Answer 19

• originates in receptors of UE and synapses in cervical SC
• travels ipsilaterally to synapse in cerebellum via inferior + superior cerebellar peduncles

Question 20

Which tracts are pyramidal?

Answer 20

corticospinal (lateral + medial), corticobulbar

Question 21

Function of Lateral Corticospinal Tract

Answer 21

fractionated, distal limb movements (voluntary movement)

Question 22

Lateral Corticospinal Tract Pathway

Answer 22

• originates in primary motor cortex (precentral gyrus), decussates at pyramidal decussation of medulla, then decends contralaterally through lateral funiculus to synapse w/ interneurons or motor neurons in ventral horn
• interneurons/motor neurons synapse w/ peripheral nerves

Question 23

Lateral Corticospinal Tract Decussation

Answer 23

yes - in medulla at pyramidal decussation

Question 24

Function of Medial Corticospinal Tract

Answer 24

postural, gross movements of proximal/axial muscles

Question 25

Medial Corticospinal Tract Pathway

Answer 25

- originates in premotor cortex and descends ipsilaterally through medial funiculus of SC to synapse w/ interneurons or motor neurons in ventral horn - interneurons/motor neurons synapse w/ peripheral nerves

Question 26

Medial Corticospinal Tract Decussation

Answer 26

does NOT decussate

Question 27

Function of Corticobulbar Tract

Answer 27

voluntary movement of facial muscles (ie. facial expression, speech, etc)

Question 28

Corticobulbar Tract Pathway

Answer 28

- originates in primary motor cortex - decussates in brainstem at different levels for each cranial nerve before synapsing with cranial nerves for facial muscles (V, VII, IX, X, XI)

Question 29

Corticobulbar Tract Decussation

Answer 29

yes - in brainstem (most fibers do)

Question 30

Which tracts are extrapyramidal?

Answer 30

reticulospinal, vestibulospinal (medial + lateral), rubrospinal, olivospinal

Question 31

Function of Reticulospinal Tract

Answer 31

(anticipatory) postural control and gross limb movements

Question 32

Reticulospinal Tract Pathway

Answer 32

- originates in reticular formation in medulla + pons, then descends ipsilaterally to motor neurons in anterior ventral gray matter - from spinal cord, it synapses w/ proximal muscles involved in balance, posture, and locomotion

Question 33

Reticulospinal Tract Decussation

Answer 33

does NOT decussate

Question 34

Function of Medial Vestibulospinal Tract

Answer 34

movement of neck + upper back muscles based on information from vestibular apparatus

Question 35

Medial Vestibulospinal Tract Pathway

Answer 35

- originates in vestibular nuclei in medulla + pons, decussates in upper medulla, then descends contralaterally to synapse w/ motor neurons in anteromedial gray matter - from spinal cord, it goes to neck, back, and postural muscles

Question 36

Medial Vestibulospinal Tract Decussation

Answer 36

yes - in upper medulla

Question 37

Function of Lateral Vestibulospinal Tract

Answer 37

maintain balance and posture as body moves

Question 38

Lateral Vestibulospinal Tract Pathway

Answer 38

- originates in vestibular nuclei in medulla + pons, then descends ipsilaterally to synapse w/ motor neurons in anteromedial gray matter - from spinal cord, it goes to ipsilateral, proximal extensor muscles

Question 39

Lateral Vestibulospinal Tract Decussation

Answer 39

does NOT decussate

Question 40

Function of Rubrospinal Tract

Answer 40

facilitate upper limb distal muscle activity (fine motor control)

Question 41

Rubrospinal Tract Pathway

Answer 41

- originates in red nucleus of midbrain tegmentum, decussates immediately at ventral tegmental decussation in midbrain - descends contralaterally to synapse w/ motor neurons in anterolateral gray matter to go to distal muscles of UE

Question 42

Rubrospinal Tract Decussation

Answer 42

yes - in midbrain at ventral tegmental decussation