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 movement awareness?

Answer 2

kinaesthesia

Question 3

what receptors are involved in proprioception?

Answer 3

muscle spindles
golgi tendon organs
joint receptors

Question 4

what are the types of muscle fibres?

Answer 4

extrafusal
intrafusal

Question 5

what muscle fibres make up the bulk of the muscle fibres and are contractile?

Answer 5

extrafusal

Question 6

where do intrafusal muscle fibres exist?

Answer 6

extrafusal
muscle spindles
specialised muscle fibres
CT capsule

Question 7

what are there in and around teeth instead of tendon organs?

Answer 7

stretch receptors in the PDL

Question 8

describe the structure of an intrafusal
muscle fibre

Answer 8

contractile end portion
non-contractile central portion (can be stretched)
contractile end portion

Question 9

what are afferents in intrafusal fibres activated by?

Answer 9

stretch

Question 10

what is the role of secondary nerve endings in the intrafusal fibre?

Answer 10

detects length of fibres

Question 11

what is the role of primary annulo-spiral nerve endings in extrafusal fibres?

Answer 11

detects length of fibres and speed of change of length

Question 12

what neurones are in the efferent part of the intrafusal
fibre?

Answer 12

gamma motor neurone

Question 13

what neurones supply extrafusal fibres?

Answer 13

alpha motor neurones

Question 14

what is the role of a muscle spindle?

Answer 14

information about muscle length
acts to maintain muscle length

jaw jerk reflex

Question 15

where are masticatory muscle spindle cells bodies?

Answer 15

mesencephalic nucleus

Question 16

where to masticatory muscle spindle afferents synapse?

Answer 16

trigeminal motor nucleus
cerebellum
cerebral cortex

Question 17

what motor neurons are active when muscle contracts?

Answer 17

alpha motor neurones
gamma motor neurones

Question 18

what is the role of gamma motor neurons in masticatory muscle spindles?

Answer 18

• Cause contraction of intrafusal fibres
• Maintain tension in spindle.
• Maintain spindle afferent activity.

**So spindles always work

Load compensation in the jaw

Question 19

what co-activates when muscles shorten?

Answer 19

alpha and gamma motor neurones

Question 20

what happens during alpha gamma coactivation?

Answer 20

• Muscle shortens.
• Spindle tension maintained.
• Spindle activity maintained.

Question 21

what happens on resistance on biting?

Answer 21

• Muscle doesn’t shorten.
• Gamma activity stretches spindle.
• Spindle activity increases.
• Alpha drive to muscle increases.

Question 22

what is the role of golgi tendon organs?

Answer 22

In tendons in series with muscle fibres.
There are very few in masticatory muscles.
They are tension receptors and have a role in inhibitory reflex, preventing of stretch of muscle.

Question 23

what are pacinian joint receptors for?

Answer 23

in ligaments for acceleration

Question 24

what are golgi joint receptors for?

Answer 24

in ligaments for position

Question 25

what are ruffini joint receptors for?

Answer 25

in capsule for movement