DC-ML Pathway

Question 1

What does it relay

Answer 1

1. Discriminitive touch sensation
2. Stereognosis
3. Vibratory sense
4. Proprioception
5. Light touch
   ALL to the contralateral sensory cortex

Question 2

It is an ascending pathway that consists of a sequence of

Answer 2

3 neurons connecting the receptor to the primary somatosensory cortex where the sensory info enters conscious perception

Question 3

Receptors

Answer 3

1. Free nerve endings
2. Peritrichial nerve endings
3. Muscle spindles
4. GTOs
5. Merkel discs
6. Meissner’s corpuscles
7. Pacinian corpuscles
8. Ruffini end organs

Question 4

Free nerve endings

Answer 4

respond to touch, pressure, and proprioception in the skin, muscles and joint capsules

Question 5

Peritrichial nerve endings

Answer 5

respond to touch around root of hair follicles

Question 6

Muscle spindles

Answer 6

proprioceptors

Question 7

GTOs

Answer 7

proprioceptors

Question 8

Merkel discs

Answer 8

discriminitive touch, superfificla pressure in skin, perception of shape and texture of an object

Question 9

Meissner’s corpuscles

Answer 9

2 point discriminative touch in skin

Question 10

Pacinian corpuscles

Answer 10

touch, deep pressure and vibratory sensation in the skin and visceral structures

Question 11

Ruffini end organs

Answer 11

proprioception - respond to stretching of collagen in the skin

Question 12

Location of the receptors

Answer 12

in the skin, muscles, tendons, ligaments, joint capsules, periosteum, viscera

Question 13

Neuron 1 cell body

Answer 13

in DRG

Question 14

Neuron 2 cell body

Answer 14

in NG or NC

Question 15

Neuron 3 cell body

Answer 15

in ventral posterior lateral nucleus of thalamus

Question 16

Fasciculus Gracilis

Answer 16

Close to midline

carries input from bottom half of the body up to the medulla

Question 17

Fasciculus Cuneatus

Answer 17

carries input from upper half of the body to the medulla

Question 18

FC is present at

Answer 18

C1 to T6 spinal cord levels (input C2 - T6 though since C1 is ONLY motor)

Question 19

FG is present at

Answer 19

all spinal cord levels

Question 20

Where is FG the thickest

Answer 20

T7 and then does not get thicker

Question 21

Where is Fc the thickest

Answer 21

C1 (not new at C1 though since only motor)

Question 22

Central process of neuron 1 runs in

Answer 22

dorsal root of a spinal nerve, enters the spinal cord, and ascends ipsilaterally in the dorsal column in either Fc or FG

Question 23

If sensory input is coming from the upper limb or upper trunk the central process does what?

Answer 23

it will enter the spinal cord and join the ipsilateral FC

Question 24

Fibers from cervical levels are located

Answer 24

most lateral

Question 25

If sensory input is coming from the lower limb or lower trunk the central process does what

Answer 25

enters the spinal cord and then joins the ipsilateral FG

Question 26

Fibers from sacral levels are

Answer 26

most medial

Question 27

If we looked at spinal cord at any spinal level we would see

Answer 27

FG in the dorsal column since it starts at bottom of spinal cord and ascends

Question 28

FG and FC together form the

Answer 28

dorsal/posterior column of the spinal cord

Question 29

The FG and FC ascend and terminate in the

Answer 29

caudal medulla where the cetnral processes of the first order neurons synapse in their respective nuclei (nuclei gracilis and nuclei cuneatus)

Question 30

Neuron 2 (second order neuron) cell body is located

Answer 30

in the NG or NC (in the medulla)

Question 31

They second order neurons give rise to

Answer 31

axons that exit the NG or NC and they curve medially to form an arc --> internal arcuate fibers

Question 32

The internal arcuate fibers

Answer 32

cross the midline (sensory decussation) and then gather to form the medial lemniscus

Question 33

The medial lemniscus is a

Answer 33

crossed tract that carries sensory information derived from the opposite side of the body

Question 34

Where does the medial lemniscus ascend to

Answer 34

the ventral posterior lateral nucleus of the thalamus where its terminals synapse with the third order neurons

Question 35

Third order neuron cell body is in

Answer 35

the VPL of the thalamus

Question 36

Third order neuron axon will exit the thalamus...

Answer 36

and ascend through the internal capsule to terminate in the postcentral gyrus (BRodmanns areas 3, 1, 2 and 3a) and the primary somatosensory cortex (in the parietal lobe)

Question 37

When sensory info gets to the primary somatosensory cortex

Answer 37

it enters conciousness

Question 38

THe primary somatosensory cortex projects to the

Answer 38

sensory association cortexx where the sensory info is interpreted

Question 39

DC-ML pathway is organized in what way

Answer 39

somatotopically from receptor to cortex

Question 40

Sensory info from one side of the body is relayed by the DC-ML to

Answer 40

the contralateral sensory cortex

Question 41

Medial surface of the postcentral gyrus blood supply

Answer 41

Hip, leg, and foot area | Anterior cerebral artery

Question 42

Lateral surface of the postcentral gyrus blood supply

Answer 42

trunk, upper limb, head area | Middle cerebral artery

Question 43

Posterior limb of the internal capsule blood supply

Answer 43

lenticulostriate arteries (branches of middle cerebral)

Question 44

Thalamus blood supply

Answer 44

thalamogeniculate arteries (branches of post cerebral artery)

Question 45

Midbrain blood supply

Answer 45

posterior cerebral artery

Question 46

Pons blood supply

Answer 46

branches of the basilar artery/ AICA

Question 47

Rostal medualla blood supply

Answer 47

ML is supplied by the vertebral artery/ant spinal artery

Question 48

Caudal medulla blood supply

Answer 48

ML here is supplied by the anterior spinal artery | NG and NC here are supplied by the post spinal arteries

Question 49

Cervical spinal cord

Answer 49

DCs here are supplied by the posterior spinal arteries

Question 50

A unilateral lesion of the dorsal column results in what kind of deficits

Answer 50

ipsilateral at and below the level of the lesion

Question 51

A unilateral lesion of the medial lemniscus will result in loss of

Answer 51

the above contralateral side

Question 52

A unilateral lesion of the third order neuron axons while traversing the internal capsule will result in loss

Answer 52

above on the contralateral side of the body

Question 53

A unilateral lesion of the primary somatosensory cortex will results in loss

Answer 53

above on the contralateral side of the body

Question 54

A lesion in the thalamus or above results in deficits in the

Answer 54

contralateral side of the body

Question 55

Sensory ataxia

Answer 55

``` sensory incoordination (stamp and stick ataxia) Losing sensation/proprioception so has to use other receptors to become consciously aware ```

Question 56

Rhomberg's sign

Answer 56

difficulty maintaining balance with eyes closed and feet together

Question 57

Anterior cerebral artery occlusion

Answer 57

sensory deficits in contralateral leg and foot

Question 58

Middle cerebral artery occlusion

Answer 58

sensory deficits in contralateral UL and face

Question 59

Occlusion of the lenticulostriate arteries

Answer 59

sensory deficits in the contralateral side of the body

Question 60

Occlusion of the posterior cerebral artery -->

Answer 60

deficits in the contralateral side of the body

Question 61

Basilar artery occlusion (in cuadal pons) -->

Answer 61

deficits in the contralateral side of the body

Question 62

Vertebral artery occlusion (in rostral medulla)

Answer 62

deficits in the contralateral side of the body