M+O 5 - proprioception

Question 1

What is proprioception?

Answer 1

awareness of position of body parts in relation to each other and surroundings

Question 2

What is kinaesthesia?

Answer 2

movement awareness

Question 3

What receptors are involved in proprioception?

Answer 3

• muscle spindles
• golgi tendon organs
• joint receptors

Question 4

What 2 types of fibres are in muscles?

Answer 4

• extrafusal
  
  • bulk of the muscle fibres
  • contractile
• intrafusal
  
  • muscle spindles
  • specialised muscle fibres
  • within a ct capsule

Question 5

Where would you find the intrafusal muscle fibres?

Answer 5

within the extrafusal fibres

Question 6

What are the majority of muscle fibres?

Answer 6

extrafusal

Question 7

What portion(s) of the intrafusal fibres are contractile?

Answer 7

the end portions

• central portion is non-contractile, it can be stretched

Question 8

What are the afferents of the intrafusal fibres activated by?

Answer 8

activated by stretch

Question 9

What are the 2 types of nerve endings in the intrafusal fibres?

Answer 9

• secondary (flower-spray) nerve endings
• primary annuli-spiral nerve endings

Question 10

What do secondary (flower-spray) nerve endings detect?

Answer 10

length of fibres

Question 11

What do primary annulo-spiral nerve endings detect?

Answer 11

length of fibres and speed of change of length

Question 12

What kind of neurones are the efferent nerves of the intrafusal fibres?

Answer 12

gamma motor neurones

Question 13

What kind of neurones are the afferent nerves of the intrafusal fibres?

Answer 13

A alpha afferent

Question 14

What type of neurone supplies the extrafusal fibres?

Answer 14

alpha motor neurone

Question 15

What happens to spindle activity when muscle is stretched?

Answer 15

spindle activity increases

Question 16

What is the role of muscle spindles?

Answer 16

• information about muscle length
• act to maintain muscle length
• load compensation

Question 17

Where do the afferent neurones of the intrafusal fibres synapse?

Answer 17

synapse directly with nerve that causes the muscle to contract, causing muscle to contract and bring it back to where it was before

Question 18

Where are the masticatory muscle spindle cell bodies?

Answer 18

trigeminal mesencephalic nucleus

Question 19

Where do masticatory muscle spindle afferents synpase?

Answer 19

• in V motor nucleus and
• other areas linked to sensorimotor regulation:
  
  • cerebellum
  • cerebral cortex

Question 20

What happens to muscle spindles if the muscle shortens (contracts)?

Answer 20

spindle collapses if loses tension and won’t work

Question 21

What maintains spindle tension so they don’t collapse?

Answer 21

gamma motor neurones

Question 22

What do gamma motor neurones cause contraction of?

Answer 22

the ends of intrafusal fibres
- maintain tension in spindle
- maintain spindle afferent activity
- alpha-gamma co-activation

Question 23

What happens to the muscles and spindles during alpha-gamma co-activation?

Answer 23

• muscle shortens (alphas)
• spindle tension maintained (gammas)
• spindle activity maintained (gammas)

Question 24

What happens to the muscles and spindles during load compensation/ resistance when biting?

Answer 24

• muscle doesn’t shorten
• gamma activity stretches spindle
• spindle activity increased
• alpha drive to muscle increases

Question 25

Where are golgi tendon organs found?

Answer 25

in tendons, in series with muscle fibres
- very few, if any, in masticatory muscles

Question 26

What are golgi tendon organs?

Answer 26

tension receptors

Question 27

What do golgi tendon organs have a role in?

Answer 27

role in (inhibitory) reflex - prevention of excess stretch of muscle

Question 28

What are the 3 kinds of joint receptors, where are they found and what is their role?

Answer 28

• pacinian - in ligaments -acceleration
• golgi - in ligaments - position
• ruffini - in capsule - movement