Ascending Spinal Cord Pathways

Question 1

What is Exteroceptive sensation?

Answer 1

Sensations from the external world

Question 2

Where are conscious sensations perceived in the brain?

Answer 2

The level of the cerebral cortex

Question 3

Where are non-conscious sensations perceived?

Answer 3

They aren’t perceived

Routed to the cerebellum

Question 4

What are the two major pathways involved in somatic sensory perception?

Answer 4

Posterior column-medial lemniscal pathway

Spinothalamic (anterolateral) pathway

Question 5

The medial portion of the spinal column, gracile fasiculus, carries information from where?

Answer 5

Legs and lower trunk

Question 6

The cuneate fasiculus carries information from where?

Answer 6

Upper trunk, Arm, neck, and occiput

T6 and up

Question 7

What is the chief function of the posterior column-medial lemniscal pathway?

Answer 7

Conscious proprioception and discriminative touch

Question 8

What is disturbance of posterior column function associated with?

Answer 8

Demyelinating diseases such as MS

Sensory ataxia

Romberg’s sign

Question 9

What are the three tracts in the anterolateral pathway?

Answer 9

Spinothalamic - pain and temperature

Spinoreticular - pain emotion/arousal

Spinomesencephalic - central modulation of pain

Question 10

Where does the secondary afferent decussate in the anterolateral pathway?

Answer 10

At the level of its origin via the anterior commissure

Question 11

Describe modality segregation in the spinothalamic tract.

Answer 11

Lateral ST - mediates noxious and thermal sensations separately

Anterior ST - mediates touch

Question 12

What is Syringomyelia?

Answer 12

Disorder associated with some kind of trauma

Syrinx (fusiform cyst) in or beside the central canal, typically in the cervical region

Initial symptoms arise from obliteration of spinothalamic fibers decussating in the white commissure

Question 13

What is the clinical presentation of syringomyelia?

Answer 13

Dissociated sensory loss

Sensitivity lost to pain and temp., retained to touch

Ulcers arising from painless cuts and burns

Disorganized joints due to loss of warning from stretched joint capsules

Question 14

What is the spinoreticular tract?

Answer 14

Arises from Laminae VI-VII

Invovled in arousing the cerebral cortect i.e. induce or maintain the waking state

Assigns some emotional context to sensation

Question 15

What is the spinomesencephalic tract?

Answer 15

Arises in laminae I and V

Involved in central pain regulation

Question 16

What are the three spinocerebellar pathways?

Answer 16

Posterior SC tract

Anterior SC tract

Cuneocerebellar tract

Question 17

Where does the Posterior SC tract originate?

Answer 17

Clarke’s nucleus

Travels through nucleus gracilis until about L2

Question 18

What peduncle does the Posterior SC tract enter the cerebellum through?

Answer 18

Inferior

Question 19

Origin, body part, peduncle for the cuneocerebellar tract?

Answer 19

Origin: Lateral cuneate nucleus

Body part: Trunk, upper extremity

Inferior peduncle

Question 20

Where does the anterior spinocerebellar tract originate, body part represented, peduncle, cross?

Answer 20

Origin: Spinal border cells

Body part: Trunk, lower extremity

Crossing: Once in cord, again in cerebellum

Peduncle: Superior

Question 21

What pathway does two-point discrimination and vibration test?

Answer 21

Posterior column-medial lemniscal pathway

Question 22

What does contralateral neglect indicate?

Answer 22

A lesion in the cortex

Question 23

What is most often affected due to a lesion in the somatosensory cortex?

Answer 23

Discriminative touch and joint position sense

Contralateral to lesion

Question 24

Where are the deficits due to a lateral pontine or medullary lesion?

Answer 24

Contralateral anterolateral pathway

Ipsilateral trigeminal pathway

Question 25

What deficits are associated with lateral pontine or medullary lesions?

Answer 25

Loss of pain and temperature sensation in the body contralateral " " in the face ipsilateral to the lesion

Question 26

What deficits occur with a medial medullary lesion?

Answer 26

Contralateral loss of vibration and joint position sense

Question 27

What deficits are associated with distal symmetrical polyneuropathies?

Answer 27

Bilateral sensory loss in a "glove and stocking" distribution, all modalities

Question 28

What is Tabes Dorsalis?

Answer 28

Inflammatory invovlement of the dorsal roots results in degeneration of the dorsal columns of the spinal cord Caused by tertiary syphilis

Question 29

What are the clinical presentations of Tabes Dorsalis?

Answer 29

Bilateral loss of fine touch, vibration and conscious proprioception Romberg and/or Lhermitte's signs may be present as well, depending on location of lesions

Question 30

What is subacute combined degeneration?

Answer 30

Deficiency in Vitamin B12 intake or metabolism Chronic demyelination and loss of axons in the dorsal and dorsolateral columns; more posterior columns than lateral corticospinal tract May also involve deep white matter of the hemispheres to produce dementia

Question 31

What is the clinical presentation of subacute combined degeneration?

Answer 31

Loss of proprioception, discriminative touch, vibration, ataxia, and spastic weakness or paralysis

Question 32

What is the clinical presentation of Multiple Sclerosis?

Answer 32

Lack of proprioceptive input - causing falling Lhermitte's sign if cervical areas are involved Loss of discriminative touch, conscious proprioception and vibration Constellation of symptoms

Question 33

What deficits will occur with large lesions to the postcentral gyrus?

Answer 33

Sensory loss involving a number of submodalities Body part correlates with position of the lesion on the gyrus

Question 34

What deficits occur with a small lesion to the postcentral gyrus?

Answer 34

Loss of two-point discrimination Difficulty in localizing painful stimulation precisely (but not loss of pain sensation) Body part affected correlates to position of the lesion on the gyrus

Question 35

What is astereognosis?

Answer 35

Loss of size/shape/texture discrimination

Question 36

What is agraphesthesia?

Answer 36

The inability to recognize letters and numbers drawn on the palm of the hand