Somatosensory

Question 1

vibration, two point discrimination, proprioception

Answer 1

dorsal column

Question 2

proprioception and muscle status

Answer 2

spinocerebellar tracts

Question 3

Which sensory receptors are pressure sensitive?

Answer 3

ruffinis endings, pacinian corpuscles, Krause’s bulbs

Question 4

Which sensory receptors are for fine touch?

Answer 4

Meissner’sm Merkels, root hair plexi

Question 5

which sensory receptors are for temp/pain

Answer 5

free nerve endings

Question 6

How are somatosensations transmitted?

Answer 6

1st neuron comes from sensation > 2nd neuron synapse is either in the spinal cord or brain nuclei> 3rd synapse is in thalamus > relayed to fourth synapse somewhere in cortex

Question 7

pseudounipolar neurons with cell bodies in a dorsal root or cranial nerve ganglion, a central process that terminates in the spinal cord or brainstem, and a peripheral receptive ending in someplace such as the skin, a muscle, or a joint

Answer 7

sensory receptor

Question 8

pacinian corpuscle

Answer 8

skin, joint capsule, vessel and mesentery walls, periosteum
1 axon
very rapidly adapting
large receptive field
vibration, pressure, proprioception (conscious and non-conscious)

Question 9

meissner corpuscle

Answer 9

located in non-hairy skin
2-5s axon per MC
low threshold
rapidly adapting
very small receptive field
40% of mechanoreceptors in hand
detect mainly fine, discriminative touch and vibration

Question 10

Merkels

Answer 10

located in skin
1 axon per cell
multiple cells per axon
low threshold
slow adapting
small receptive field (better spatial resolution)
25% of mechanoreceptors in hand
pressure

Question 11

ruffini corpuscle

Answer 11

located in skin
1 axon per cell
low threshold
slow adapting
small receptive field
stretching of skin

Question 12

thermoreceptors adaption

Answer 12

Painful cold = limited adaptation
Cool = rapid adaptation (A&)
Warm = rapid adaptation (C)
Painful heat = limited adaptation (A&, C)

Question 13

TRPV let these ions in

Answer 13

Ca and Na

Question 14

neurotransmitters, peptides, lipids, proteases, neurotrophins, cytokines, chemokines. prostaglandins, K +, H +, histamine, bradykinin, serotonin, NGF. Bind to..

Answer 14

inflammatory soup bind to nocioceptors

Question 15

where do mechanorecptors project

Answer 15

lamina II through VI medially

Question 16

Where do A& and C fibers project?

Answer 16

Lamina I through V laterally

Question 17

What is path of lateral or anterior spinothalamic tracts

Answer 17

Sensory nerve axons from DRG enters into Lissauer’s tract and travels 2-3 spinal levels (↑ or ↓)
synapses on 2nd neuron in dorsal horn (lamina I,V)
axon of 2nd neuron crosses to the other side of the spinal cord in the white anterior commissure
then enters either:
1) Anterior Spinothalamic if crude touch/pressure
2) Lateral spinothalamic if pain or temp

Question 18

where does 3rd synapse occur in the latera/anterior spinothalamic tracts?

Answer 18

the VPL of thalamus

Question 19

How is pain/temp pathway in head different?

Answer 19

Axons of the DRG neurons relaying pain and temperature sensation from the head and neck (CN5, 7, 9, 10) synapse in the Spinal nucleus of V (Spinal trigeminal nucleus).

The axons of the Spinal nucleus of V neurons cross the midline in the medulla and coalesce to form the Ventral Trigeminothalamic tract and synapse in the Ventral posterior medial (VPM) thalamic nucleus.

Question 20

How does PAQ manage pain?

Answer 20

periaqueductal gray receives information from the hypothalamus, amygdala, and cortex
send signals to the raphe nucleus, and the reticular formation
From these nuclei, second-order signals are transmitted down the dorsolateral columns in the spinal cord to a pain inhibitory complex located in the dorsal horns of the spinal cord.
enkephalin (type of endorphin) and serotonin are the primary neurotransmitters

Question 21

from Ib afferents, increases muscle tension

Answer 21

golgi tendon

Question 22

Where do the dorsal medial lemniscus pathways cross before 3rd neuron?

Answer 22

Fasciculus Gracilis synapse onto the 2nd neuron in the Nucleus Gracilis . Fasciculus Cuneatus synapse onto the 2nd neuron in the Nucleus Cuneatus
The 2nd neuron CROSSES the midline as the internal arcuate fibers in the medulla and coalesce to form the medial lemniscus to the other side of the brain
synapses on the 3rd neuron in the VPL nucleus of the thalamus then to the 4th neuron in the somatosensory cortex

Question 23

How is vibration, two point discrimination, and proprioception relayed from the head?

Answer 23

Axons of the trigeminal ganglion neurons relaying touch sensation from the head enter the brainstem and synapse in the main sensory nucleus of V in the pons. Those axons either:
1- cross the midline in the pons as the Ventral Trigeminothalamic tract and synapse in the Ventral posterior medial (VPM) thalamic nucleus.
2- ascend without crossing as the Dorsal Trigeminothalamic tract in the Ventral posterior medial (VPM) thalamic nucleus.

Question 24

What info does cerebellum receive?

Answer 24

nonconscious from Muscle spindle afferents (Ia) and Golgi tendon organ afferents (Ib). This information about muscle tension goes to the cerebellar hemisphere (coordinates muscle movement—same side of the body).

Question 25

What is path of nonconscious upper limbs to inferior cerebellar peduncle?

Question 26

What is path of nonsconscious lower limbs to inferior cerebellar peduncle?

Answer 26

This is dorsal spinocerebellar tract. Axons of the DRG neurons from the muscle spindle travel with the fasciculus gracilis (do not cross the midline) then synapse on the Clarkes nucleus (C8-L2). The axons of Clarkes nucleus neurons form the dorsal spinocerebellar tract and enter the cerebellum via inferior cerebellar peduncle (do not cross the midline).