Senses and Perceptions 2

Question 1

Where do afferent neurones begin and where do efferent neurones end?

Answer 1

afferent - skin, muscle
efferent - muscle

Question 2

What is each nerve fibre encased by?

Answer 2

endoneurium

Question 3

What is each fascicle encased by?

Answer 3

perineurium

Question 4

What are groups of fascicles encased by?

Answer 4

epineurium

Question 5

What are myelinated axons surrounded by?

Answer 5

myelin sheath from Schwann cells

Question 6

What are characteristics of a-alpha fibres?

Answer 6

myelinated, large diameter, conducts very fast, sensory (proprioception) and motor information from skeletal muscles

Question 7

What are characteristics of a-beta fibres?

Answer 7

myelinated, medium diameter, conducts fast, mechanoreceptors of skin

Question 8

What are characteristics of a-delta?

Answer 8

myelinated, small diameter, conducts slowly, pain and temperature

Question 9

What are characteristics of C axons?

Answer 9

non-myelinated, small diameter, conducts very slowly, pain, temperature, itch

Question 10

What are the horns found in grey matter?

Answer 10

dorsal
intermediate
ventral

Question 11

In what horns does motor and sensory innervation take place?

Answer 11

dorsal - sensory
ventral - motor

Question 12

What are dermatomes?

Answer 12

areas of skin on your body that are innervated by specific regions of the spine.

Question 13

What are myotomes?

Answer 13

muscles in the body are supplied by segments of the spinal cord and their corresponding spinal nerves.

Question 14

What components of the trigeminal nerve are solely sensory?

Answer 14

ophthalmic
maxillary

Question 15

What component of the trigeminal nerve has motor and sensory function?

Answer 15

mandibular

Question 16

How many neurones is the sensory pathway composed of?

Answer 16

3 inter-connected neurones

Question 17

What do 1st (primary) order sensory neurones bring information from?

Answer 17

from periphery to spinal cord/brainstem

Question 18

What do 2nd (secondary) order sensory neurones bring information from?

Answer 18

from spinal cord/brainstem to thalamus

Question 19

Where do 3rd (tertiary) order sensory neurones bring information from?

Answer 19

thalamus to cerebral cortex

Question 20

Where does the sensory pathway direct?

Answer 20

to opposite side of the body

Question 21

What neurone usually cross the midline boundary?

Answer 21

2nd order

Question 22

Why is the sensory homunculus distorted?

Answer 22

Body regions with high sensory innervation (i.e. high density of receptor endings and small overlapping receptive fields) have greater cortical representation

Question 23

Describe the somatic mechanosensation Dorsal Column-Medial Lemniscal Pathway (body)

Answer 23

afferent 1st order nerve fibre travels from skin to dorsal horn to synapse with 2nd order nerve fibre at brainstem (oblongata medulla)
2nd order crosses over to reach 3rd order at thalamus
3rd order sends out to the somasensory cortex

Question 24

Describe the somatic mechanosensation Posterior (Dorsal) Trigeminothalamic Pathway (face)

Answer 24

trigeminal nerve 1st order synapses at brainstem nucleus (medulla)
2nd order neurone crosses over to the thalamus to connect to 3rd order
3rd order sends out to the somasensory cortex

Question 25

Describe the somatic nociception Spinothalamic Pathway (body)

Answer 25

afferent 1st order nerve synapses at the dorsal horn 2nd order crosses the midline to the thalamus 3rd order sends out to the somasensory cortex

Question 26

Describe the somatic nociception Anterior (Ventral) Trigeminothalamic Pathway (face)

Answer 26

trigeminal nerve 1st order synapses at spinal trigeminal nucleus of spinal cord 2nd order neurone crosses over to the thalamus to connect to 3rd order 3rd order sends out to the somasensory cortex

Question 27

What is sensation?

Answer 27

The process of sensing our environment (touch, taste, sight, smell) by activation of sensory pathways

Question 28

What is perception?

Answer 28

The interpretation of sensory input (interpretation of sensation)

Question 29

What is stereognosis?

Answer 29

The mental perception of objects referenced by touch via memory, texture, weight and size

Question 30

Where does stereognosis retrieve information and regulate activity?

Answer 30

hippocampus; basal ganglia; motor cortex

Question 31

What is Proprioception (Kinesthesia)?

Answer 31

the sense that lets us perceive the location, movement, and action of parts of the body.

Question 32

What sensations does the DCML pathway process?

Answer 32

fine touch, 2 point discrimination, proprioception