Lecture 10: Ascending Pathway I

Question 1

True or False: The DC-ML is concerned with conscious appreciation of fine touch, two point discrimination, conscious proprioception, and vibrations

Answer 1

True

Question 2

True or False: The DC-ML deals with highly localizable and discriminative sensations

Answer 2

True - they’re known as epicritic sensations

Question 3

Where are the first, second, and third order neurons of the DC-ML located?

Answer 3

1st: DRG
2nd: Dorsal column nuclei (medulla)
3rd: VPL nucleus (thalamus)

Question 4

True or False: The first order neuron of the DC-ML is a pseudounipolar neuron with a peripheral and central axonal process

Answer 4

True

Question 5

Which three tactile mechanoreceptors are associated with the DC-ML?

Which two structures are involved in conscious proprioception in the DC-ML?

Answer 5

Tactile Mechanoreceptors:
1. Meissner’s and 2. Pacinian corpuscles; 3. Free nerve endings on hair follicles

Conscious Proprioception:
1. Muscle Spindles (Ia and II)
2. Golgi Tendon Organs (Ib)

Question 6

True or False: In the DC-ML, Meissner Corpuscle is associated with two point discrimination/fine touch while Pacinian Corpuscle is associated with pressure and vibration

Answer 6

True

Question 7

Where do the peripheral axonal processes of the DC-ML originate from? where do they end up?

Answer 7

Peripheral receptors to cell body in DRG

Question 8

True or False: Both the peripheral and central axonal process of the DC-ML are associated with large, heavily myelinated fibers

Answer 8

True

Question 9

Type Ia, Ib, and II are associated with ______
A. Central axonal processes
B. Peripheral axonal processes

Answer 9

B. Peripheral axonal processes

Question 10

Once in the spinal cord, the central axonal process will give off small collateral branches that will terminate in the spinal gray matter to facilitate ___

Answer 10

reflexes

Question 11

The main axon of the first neuron of the DC-ML will leave the dorsal gray matter without synapsing and enter the ___ ____ to help form either the ___ or ____

Answer 11

dorsal funiculus; FG; FC

Question 12

Which two structures make up the Dorsal (Posterior) Column?

Answer 12

FG and FC

Question 13

___ is located at ALL spinal cord levels and carries sensory information to the lower extremities
A. Fasiculus cuneatus
B. Fasiculus gracilis

Answer 13

B. Fasiculus gracilis

Question 14

___ is located only at spinal cord levels T6 and above and carries sensory information to the UE

A. Fasiculus cuneatus
B. Fasiculus gracilis

Answer 14

A. Fasiculus cuneatus

Question 15

In the DC-ML, the sacral spinal levels are most ___ while fibers of the cervical spine are most ___ to dorsal columns
A. medial; lateral
B. lateral; medial

Answer 15

A. medial; lateral

Question 16

True or False: The arrangement of the body parts represented in the dorsal column pathway is a good example of somatotophy

Answer 16

True

Question 17

True or False: The somatotopic organization of the DC-ML persists throughout entire course of the ascending pathway

Answer 17

True

Question 18

Which axonal processes of the DC-ML terminate (synapse) on neurons in the dorsal column nuclei (NG and NC) in the caudal medulla?
A. Peripheral Axonal Processes
B. Central Axonal Processes

Answer 18

B. Central Axonal Processes

Question 19

The NG receives axons of the ___ and corresponds to the gracile tubercle

The NC receives axons of the ___ and corresponds to the cuneate tubercle

Answer 19

FG
FC

Question 20

True or False: Axons of the dorsal column nuclei neurons are small and minimally myleinated

Answer 20

False - they are large and heavily myelinated

Question 21

Which neurons of the DC-ML course ventromedially through the medullary tegmentum, ultimately crossing midline?
A. First order neurons
B. Second order neurons
C. Third order neurons

Answer 21

B. Second order neurons

Question 22

Once second order neurons of the DC-ML cross midline, they enter the ____

Answer 22

IAF (interarcuate fibers)

Question 23

The internal arcuate fibers will coalesce on the contralateral side of the medulla, dorsal to pyramidal tracts, known as ___

Answer 23

ML (medial lemniscus)

Question 24

Ventral fibers arise from ____
Dorsal fibers arise from ____

Answer 24

Nucleus gracilis
Nucleus cuneatus

Question 25

What three things happens when the medial lemniscus travels through the brainstem?

Answer 25

1. Changes relative position and orientation 2. Terminates in thalamus 3. Synapses on third order neuron

Question 26

Where do the fibers of the medial lemniscus synapse?

Answer 26

Neurons in the VPL (ventral postero-lateral nucleus of thalamus)

Question 27

Where do axons of the VPL neurons project out of, then enter, then terminate in?

Answer 27

Thalamus => Posterior limb (internal capsule) => Somatosensory Cortex

Question 28

Where is the primary somatosensory cortex located (S-I) A. Post-central gyrus B. Superior parietal lobule C. Parietal cortex

Answer 28

A. Post-central gyrus

Question 29

Which Brodmann Areas correspond to the Primary Somatosensory Cortex? Which Brodmann Areas correspond to the Somatosensory Association Cortex?

Answer 29

Primary Somatosensory Cortex - Brodmann 3, 1, and 2 Somatosensory Association Cortex - Brodmann 5 and 7

Question 30

What are the four subdivision of the primary somatosensory cortex?

Answer 30

Brodmann Area 3a, 3b, 1, and 2

Question 31

Where do most thalamic outputs of The Primary Somatosensory Cortex terminate? A. Area 1 and 2 B. Area 3a and 3b C. Area 3a and 3c D. Area 1 and 3b

Answer 31

B. Area 3a and 3b

Question 32

Each subdivision of the primary somatosensory cortex contains a sensory homunculus. Which body part has a disproportionately larger cortical representation?

Answer 32

Fingers

Question 33

In the subdivisions of the primary somatosensory cortex (S-I) - the leg is represented more ___, while trunk, arm, fact are represented more ____

Answer 33

medially; laterally

Question 34

Where is the Parietal Association Cortex (Somatosensory Association Cortex) locate? A. Cortex of inferior parietal lobe B. Cortex of superior parietal lobe

Answer 34

B. Cortex of superior parietal lobe

Question 35

Which of the following gets input from: S-I, S-II, Pre-motor cortex, limbic system, vestibular system, auditory, and visual systems? A. Primary Somatosensory Cortex B. Posterior Parietal Lobe (Somatosensory Association Cortex)

Answer 35

B. Posterior Parietal Lobe (Somatosensory Association Cortex)

Question 36

True or False: Higher order processing of somatosensory information, coupled with other information, occurs in the Somatosensory Association Cortex

Answer 36

True

Question 37

Which of the following aids in formation of a mental "image" of the body A. Primary Somatosensory Cortex B. Posterior Parietal Lobe (Somatosensory Association Cortex)

Answer 37

B. Posterior Parietal Lobe (Somatosensory Association Cortex)

Question 38

Lesions in which cortical area will often result in hemineglect syndrome? A. Parietal Association Cortex / Somatosensory Association Cortex B. Primary Somatosensory Cortex

Answer 38

A. Parietal Association Cortex / Somatosensory Association Cortex

Question 39

Information about unconscious proprioception from the body is conveyed to the cerebellum via ____

Answer 39

spinocerebellar tracts

Question 40

Dorsospinalcerebellar tract projects through the _____ while Ventral spinocerebellar tracts project through the ___

Answer 40

ICP (inferior cerebellar peduncle); SCP (superior cerebellar peduncle)