In Vivo Skills 2

Question 1

What are the Neuronal pathways for pain and touch somatosensory systems?

Answer 1

• Receptor endings in skin
• Cell body in dorsal root
  ganglion
• Synapse on interneurons and
  projection neurones
• Projection neurones go to
  thalamus
• Information passed to
  forebrain and other structures

Question 2

Explain the range of receptors in the skin

Answer 2

• 2 types of skin
  1. Hairy
  2. Hairless
• Specialised structures in the skin
• Innervated by primary afferent fibres

Question 3

Label this diagram

Answer 3

YKWTD

Question 4

What are A-Beta fibres?

Answer 4

• Thickest fibres with highest conduction velocity
• Convey light touch, pressure, vibration, and some pain sensations

Question 5

What arre A-Delta fibres?

Answer 5

• Medium thickness fibres with high conduction velocity (saltatory)
• Convey senses of touch, temperature, and sharp pain

Question 6

What are C-fibres?

Answer 6

• Thinnest fibres which use continuous conduction (grouped in bundles)
• Detect nocuous temperature, itch, significant pressure, and dull pain

Question 7

How many Laminae does the spinal cord contain?

Answer 7

• 10 layers

Question 8

Label this

Answer 8

YK

Question 9

Connection between Somatosensory pathways and evolution?

Answer 9

• The pathways by which somatosensory info is detected and processed are well conserved across species

Question 10

Label this diagram and Give me 2 facts

Answer 10

• Specialised areas for processing somatosensory info
• Larger than other senses(apart from vision)

Question 11

Label this

Answer 11

YK

Question 12

What are receptive fields?

Answer 12

• A receptive field is the area of the
  body which when stimulated an
  individual neuron will fire
• Some neurones have very large
  receptive fields
  Some have very small
• Not all the same, depends on the
  neuron and the area of body it is in

Question 13

What’s more sensitive, small or large receptive fields?

Answer 13

• Small fields are far more sensitive as there are far more receptors in a smaller area
• Allows for point differentiation

Question 14

Altering receptive field

Answer 14

Need to re-watch

Question 15

What are the temperature ranges for Cutaneous thermal receptors?

Answer 15

• Painful cold:Below 15
• Cold: approx 10-43
• Warm: approx 28-48
• Painfully hot: above 45

Question 16

What are feature detecting Neurons?

Answer 16

• Different receptors and
  different sensory
  neurones allow us to
  detect different features
• Different thermal
  detection ranges for
  different members of
  the T RP channels (i.e
  TRPVI )

Question 17

Finish this table

Answer 17

YK

Question 18

What is Evoked potential testing?

Answer 18

• Physical stimulus (small electric pulse)
• Response in Somatosensory cortex recorded via EEG
• Time to respond to one parameter recorded

Question 19

What is quantative sensory testing?

Answer 19

• Determines sensation
  and pain thresholds
• Cold and warm
• Vibration sensation
  Compare to normative
  values
• Ask patients when they
  feel the sensation

Question 20

What is a method of testing receptive field size?

Answer 20

• The paper clip test

Question 21

What are Von frey hairs and what are they used for?

Answer 21

• Used for measuring receptor sensitivity with Von Frey hairs
• Monofilament that bends
• The diameter (thickness) of
  each hair is different so that
  they bend when you press
  down on them
• The thickness determines the
  force that is applied to the
  tissue (in this case the skin)