Somatic Sensations

Question 1

What is the function of Free Nerve Endings in somatic sensation?

Answer 1

respond to pain, touch, and pressure

Question 2

What are Meissner Corpuscles? What type of nerve fibers do they use?

Answer 2

rapidly adapting receptors that respond to touch (end of finger tips)

large myelinated beta type A fibers

Question 3

What are Merkel Disks? What type of nerve fibers do they use?

Answer 3

slowly adapting receptors for touch and pressure (hairy and non hairy skin)

myelinated beta type A fiber

Question 4

What are Pacinian corpuscles?

Answer 4

rapidly adapting receptors that respond to vibration

Question 5

What are Ruffini end organs? Where are they generally located?

Answer 5

slowly adapting receptors that respond to heavy touch and pressure (located in deep layers of the body)

Question 6

What are Hair End Organs?

Answer 6

rapidly adapting receptors that respond to touch; located at the base of hair follicles

Question 7

What type of nerve fibers transmit touch?

Answer 7

mostly beta-type A fibers

Question 8

What nerve fibers relay vibration?

Answer 8

beta-type A fibers

Question 9

What somatic nerve fibers relay pain?

Answer 9

free nerve endings

Question 10

What spinal cord laminae does crude touch originate from?

Answer 10

1, 4, 5, and 6

Question 11

The anterior and posterior spinothalamic tracts terminate at which thalamic nuclei? What functions?

Answer 11

VPL (body)

VPM (face)

Posterior Thalamic Nuclei

• touch and temperature sensations

Question 12

The spinoreticular tract terminates at what thalamic nuclei? What function(s) does it contain?

Answer 12

Intralaminar thalamic nucleus

• pain

Question 13

The nucleus gracilis is located ________ and responsible for _______.

Answer 13

medial medulla

lower limb fine touch, vibration, proprioception

Question 14

The nucleus cuneatus is located ________ and responsible for _______.

Answer 14

lateral medulla

upper limb fine touch, vibration, proprioception

Question 15

The axons from the nucleus gracilis and cuneatus cross through arcuate fibers to form _______. What other fibers do they join?

Answer 15

medial lemniscus

main sensory nucleus of Trigeminal nerve and Upper Spinal Nucleus of V

Question 16

Where does the medial lemniscus terminate?

Answer 16

VPL (body)

VPM (face)

Question 17

What is the somatotopic organization at the spinal cord, thalamus, and cortex?

Answer 17

lower limbs are medially in the spinal cord, laterally in the thalamus, and medially in the cortex

Question 18

What is the pathway for lower limb proprioception?

Answer 18

Clark’s column neurons through the dorsal spinocerebellar tract to the cerebellum

Question 19

What is the pathway for upper limb proprioception?

Answer 19

fasciculus cuneatus fibers synapse on accessary cuneate nucleus in the caudal medulla and then enter the cuneocerebellar tract before entering the cerebellum

Question 20

Cortex Layers 5 and 6 have projection fibers which project to the _____ and ______, respectively.

Answer 20

brainstem/spinal cord

thalamus

Question 21

Fast pain is relayed by what fibers?

Answer 21

delta-type A fibers

Question 22

Slow pain is relayed by what fibers?

Answer 22

type C fibers

Question 23

What is Lissauer’s tract?

Answer 23

tract in the spinal cord by which pain fibers ascend or descend prior to entering the dorsal horns

Question 24

Fast pain is transmitted within the ______ tract while slow pain is through the ______ tract.

Answer 24

neospinothalamic

paleospinothalamic

Question 25

Fast pain is transmitted through what spinal cord lamina?

Answer 25

Lamina 1 (lamina marginalis)

Question 26

Slow pain is transmitted through what spinal cord lamina?

Answer 26

2 and 3 followed by 5-8

Question 27

What areas release enkephalins?

Answer 27

periaquaductal gray and periventricular hypothalamus

Question 28

How does amitryptyline decrease pain?

Answer 28

increase 5-HT which activates pain inhibitory complex in the spinal cord

Question 29

How do NSAIDs decrease pain?

Answer 29

decrease prostaglandin production which increase pain receptor sensitivity

Question 30

DBS of what areas have been used to treat chronic pain?

Answer 30

periaqueductal gray and preventricular hypothalamus

Question 31

What is hyperalgesia?

Answer 31

increased sensitivity (i.e. decreased threshold) to pain

Question 32

What is hyperpathia?

Answer 32

increased reaction to pain (painful stimuli causing greater than expected pain response)

Question 33

What is allodynia?

Answer 33

Non-painful stimuli causing pain

Question 34

What is Dejerine-Roussy syndrome? What is it caused by?

Answer 34

usually caused by posteroventral thalamic strokes

beginning symptoms are ataxia and contralateral hemianesthesia, with eventual return of crude sensation but also increased pain and discomfort on that contralateral side

Question 35

What nerve is responsible for referred pain from supratentorial cranial structures? How does it manifest?

Answer 35

Trigeminal nerve; frontal headache

Question 36

What nerves are responsible for the referred pain from infratentorial cranial structures? How does it manifest?

Answer 36

C2, CN IX, CN X

occipital and retroauricular headache

Question 37

What causes post lumbar puncture headaches?

Answer 37

decreased CSF allows weight of the brain to stretch blood vessels bridging from the brain to the skull