Ascending spinal cord tracts

Question 1

What kinds of sensory input does the dorsal column tract receive?

Answer 1

Fine touch, 2 point discrimination, proprioception

F-2-P

Question 2

Where do the dorsal column fibers terminate?

Answer 2

At the dorsal column nuclei in medulla

Question 3

State the course of the dorsal column tract.

Answer 3

1. After passing through the dorsal root ganglion (1st order neurons) and entering the dorsal horn of the spinal cord, the fibers ascend without crossing to the lower brainstem
2. The fibers ascend in the dorsal portion of spinal cord to their target (secondary neurons) in caudal medulla, the dorsal column nuclei (gracile and cuneate nuclei), where they cross the midline via the lemniscal decussation at the level of medulla to form the medial lemniscus
3. Second-order neurons ascend and synapse with neurons in ventral posterolateral thalamic nuclei (third order nuclei) in the thalamus
4. relayed up to primary somatosensory cortex

Question 4

Fibers from the arm or legs is more lateral in the dorsal column tract of the spinal cord?

Answer 4

Arm (FC is more lateral to FG)

Question 5

If dorsal column system is lesioned, it produces ______________________, a movement disorder resulted from sensory impairment > difficulty in walking

Answer 5

Sensory ataxia

Question 6

What is the Romberg’s sign? Why will it happen?

Answer 6

Inability to maintain steady posture with feet close together after the eyes are closed, due to loss of proprioceptive loss in dorsal column tract

Question 7

Lesion in the dorsal column tract affects muscle coordination, producing a __________________gait, but can be compensated by _____________________.
This can be contrasted to lesions in _________________, where other sensations cannot compensate for the lesion.

Answer 7

Stamp and stick;
vision;
cerebellum

Question 8

What are the sensory inputs of the spinothalamic tract?

Answer 8

Pain, temperature, nociception (crude touch)

Question 9

DRG fibers synapse with _________________ cells or spinothalamic neurons; axons of the latter form the spinothalamic tract

Answer 9

gelatinosa

Question 10

Spinothalamic tract decussate at the __________ white commissure in spinal cord at what level?

Answer 10

ventral;

at the level of entry

Question 11

Give the functions of the 2 spinothalamic tracts.

Answer 11

1. Lateral spinothalamic tract
   - mediates noxious and thermal sensations (with somatotopic order)
2. Anterior spinothalamic tract: mediates light touch

Question 12

Sensation from sacral parts is carried in the _________ parts of spinothalamic tracts while that of the cervical regions are carried by ________ parts of the spinothalamic tracts.

Answer 12

Lateral;

medial

Question 13

The spinothalamic tracts ascend in the ____________________ and lateral brainstem to thalamus.

Answer 13

lateral funiculus

Question 14

Ascending pain/temperature afferent fibers are somatotopically arranged within the anterior portion of the ______________________, those from the leg is more ____________ to those from the arms.

Answer 14

lateral funiculus,

lateral

Question 15

State the course of the spinothalamic tract.

Answer 15

1. Fibers enter the dorsal horn to the substantia gelatinosa (layer II of gray matter), crossing the midline at the anterior white commissure
2. Fibers ascends in the anterior portion of the lateral funiculus in the lateral and anterior spinothalamic tract
3. Tract travels up to the pons, medulla and midbrain
4. ends at ventral posterior thalamic nucleus
5. third order neuron send signals to the primary sensory cortex

Question 16

Pain, thermal and tactile information is passed to the __________________ of the midbrain through the spinotectal tract for the purpose of spinovisual reflexes.

Answer 16

superior colliculus

Question 17

______________ and _____________ tracts are the lateral portion of the lateral funiculus.

Answer 17

Spinoreticular;

Spinocerebellar

Question 18

Unconscious information from muscles, joints, skin and subcutaneous tissue reaches the cerebellum by what ways?

Answer 18

1. Anterior spinocerebellar tract
2. Posterior spinocerebellar tract
3. Cuneocerebellar tract

Question 19

__________________ tract from the spinothalamic tract provides pathway from muscles, joints and skin to the reticular formation.

Answer 19

Spinoreticular

Question 20

Cordotomy is done to interrupt the ________________ for the relief of intractable pain.
Where the cut should be for analgesia on the right below the lesion?

Answer 20

spinothalamic tract;

on the left cervical cord

Question 21

_______________develops with a fusiform cyst around the central canal at the cervical region, leading to compression and degeneration of cells in the ___________________.

Answer 21

Syringomyelia;

anterior white commissure

Question 22

How to determine whether a lesion is in the brain or in the spinal cord?

Answer 22

With lesions in the brainstem of higher, deficits of pain, touch and proprioception are all contralateral.
With spinal cord lesions, the deficit in pain perception is contralateral to the lesion whereas other deficits are ipsilateral.

Question 23

What is the sensory input for spinoreticulothalamic tract?
Are these projections unilateral or bilateral?
Which tract does it follow closely to?

Answer 23

Emotional parts of sensation;
Bilateral projections;
close to spinothalamic tract

Question 24

State the course of spinoreticulothalamic tract.

Answer 24

1. DRG > route similar to spinothalamic tract > synapse with interneurons that synapse with projection neurons that send fibers to RF in brainstem
2. from RF to intralaminar nucleus in thalamus
3. projects to whole area of the cerebral cortex

Question 25

What are the spinocerebellar tracts and what sensory input do they receive?

Answer 25

1. posterior (dorsal) spinocerebellar tract
2. anterior (ventral) spinocerebellar tract - bilateral, so not significant

• dorsal spinocerebellar tracts carry unconscious proprioception to the cerebellum

Question 26

State the course of the spinocerebellar tract when receive signals from lower limb and trunk.

Answer 26

1. DRG receive signals from trunk > relay muscle signals from muscle spindles, Golgi tendon organs, touch and pressure receptors to a group of neurons in thoracic segments of the spinal cord
2. Neurons form the Clarke’s nucleus in the middle region of gray matter
3. Axons of the neurons form the dorsal spinocerebellar tract, send signals to ipsilateral cerebellar hemisphere

NO CROSSING

Question 27

State the course of the spinocerebellar tract when receive signals from upper limb and neck.

Answer 27

1. DRG in cervical regions > axons synapse with neurons in medulla known as accessory cuneate nucleus
2. join the spinocerebellar tract to send signals to the cerebellum

Question 28

Clarke’s nucleus is not present above which level?

Answer 28

C8