Neuroscience Week 3: Somatosensory Systems

Question 1

Mechanical Receptors

6 listed

Answer 1

• Meissner Corpuscles
• Merkel Discs
• Hair Follicle receptors
• Ruffini endings
• Pacinian corpuscles
• Muscle spindles

Question 2

Nociceptors examples

2 listed

Answer 2

• A𝛿 mechanical; heat
• C-polymodal

Question 3

Thermoreceptors example

Answer 3

free nerve endings

Question 4

Meissner Corpuscles Function

Answer 4

Tactile: shape/surfaces. Stereognosis

Question 5

Merkel Discs Function

Answer 5

Tactile: indentation. Two-point sense, graphesthesia, flutter (low frequency)

Question 6

Hair Follicle receptors Function

Answer 6

Tactile in hairy skin

Question 7

Ruffini Endings Function

Answer 7

Stretching & Shapes. Stereognosis, pressing or squeezing

Question 8

Pacinian Corpuscles Function

Answer 8

Vibrations. High Frequency

Question 9

Muscle Spindles Function

Answer 9

Proprioception. Limb position, motion sense

Question 10

Vibration high frequency

Answer 10

256 vibrations / sec

Question 11

Vibration Low Frequency

Answer 11

125 vibration/sec light flutter

Question 12

A𝛿 Mechanical Receptor function

Answer 12

heat, pinprick at or >45C, damaging chemical information

Question 13

C-polymodal Receptor Function

Answer 13

Tissue damage

Question 14

The termperature sensing warning device

Answer 14

Noiception: a warning device

A. Nociceptive spinal reflexes triggered at ~45°C (113°F)

B. Maintenance >/= 45°C (113°F) is tissue damaging

Question 15

Pain Perception

Answer 15

• moments after the nociceptive reflex withdrawal the stimulus is perceived as pain
• Delay in perception is due to the time required to relay nociceptive signals via the spinothalamic tract to the 3rd order neurons in the thalamus, and they relay from thalamus to somatosensory cortex
• Nociceptive reflexes and the “pain threshold” serve a protective role

Question 16

Pain as a Recuperative Healing Mechanism

Answer 16

Induces disuse of the injured area to promote healing

Question 17

Myelination of Aα and function

Answer 17

• Heavily myelinated
• limb position and motion

Question 18

Myelination of Aß and function

Answer 18

low threshold stimuli

gentle touch

modest myelinated

Question 19

Myelination of Aδ fibers

Answer 19

Lightly myelinated

first fast pain

Bright and well localized pain

sets off protective reflexes

Question 20

C fiber Myelination and function

Answer 20

Unmyelinated

smaller than Aδ fibers

conduct about 1yd/sec

poorly localized

long pain, dull, aching

Triggers disuse of the injured site

protection for healing

much more proportionality 70%

Question 21

Which nerve fibers set off protective reflexes

Answer 21

Aδ fibers

Question 22

Identify pathway and where the 2nd order neuron is located

Answer 22

Question 23

Fill in

Answer 23

motion is passive motion so someone is moving your arm

Question 24

Funiculus vs Fasciculus

Answer 24

Funiculus is a fiber bundle

Fasciculus is a thinner fiber bundle

many fasciculi make up a funiculus

Question 25

Answer 25

Question 26

Identify

Question 27

Dorsal columns- medial lemniscus pathway

Answer 27

* ascend fasiculus gracilis * fibers from T6 and above will ascend in the cuneate fasiculus (general sense from upper trunk and upper limbs) synapse on nucleus cuneatus of medulla * fibers below T6 ascend in the fasiculus gracilis (general sense from the lower trunk and lower limbs) synapse on nucleus gracilus of medulla * medial meniscus is the name of the fiber tracts after the decussation in the medulla

Question 28

3D diagram of the dorsal columns - ML pathway

Answer 28

Question 29

Spinothalamic Tract

Answer 29

pain and temperature from the body primary neurons dorsal root ganglion 2ndary ipsilateral dorsal horn decussate 3rtiary in thalamus to the primary somatosensory cortex pay attention to where lesions are in relation to decussation

Question 30

Spinothalamic tract 3D diagram

Answer 30

if there was a lesion at the ventral white commissure would have deficits bilaterally because both sides decussate there

Question 31

Tract responsible for unconscious proprioception

Answer 31

Spinocerebellar

Question 32

Identify know the blood supply

Question 33

Identify know the blood supply

Question 34

Identify know the blood supply

Question 35

Vertebral-basilar system

Answer 35

* Know Vertebral-Basilar system * vertebral arteries * Posterior inferior cerebellar artery (PICA)

Question 36

Blood Supply to the spinal cord

Answer 36

both posterior spinal arteries supply the dorsal columns if in the anterior spinal would have ipsilateral motor deficits and contralateral pain and temp deficits

Question 37

Draw and label each pathway and include 1st 2nd3rd order neurons and location of decussations

Question 38

Question 1

Answer 38

Question 39

Question 2

Answer 39

Question 40

Question 3

Answer 40

Question 41

Question 4

Answer 41

Question 42

Question 5

Answer 42

Question 43

Question 6

Answer 43

Question 44

Question 7

Answer 44