Week 2 (MC) - Sensory proprioception

Question 1

What is the Sensory Poly-neuropathy?

Answer 1

Degeneration of the large afferent fibres carrying proproceptive and tactile inputs

Afferent Neural information returning to the CNS is inhibited

Tells us that th sensory system (proprioception) is vital for movement control

Question 2

What are the 5 common properities of the sensory system when stimulated?

Answer 2

1. Modalities - vision, touch etc and their receptors
2. Location - where is it on the body
3. Intensity - How much / many
4. Timing - When and how long
5. Transduction - conversion of signal to neural signalling for the CNS (e.g. mechanoreceptors)

Question 3

What are the 4 types of touch modality?
Where is each located and what do they detect?

Answer 3

Meissners Corpuscle
- Located close to the skins surface and is a precise guage of senstivity
- Detects change in pressures
- Is fast adapting Type I

Merkel Cells
- Deeper than Meissners but still near skin surface
- Detects consistency of a stimulus
- Is slow adapting Type I

Pacinian Corpuscle
- Located in the Epidermis
- sensing sudden impacts or vibrations rather than sustained pressure
- Fast adapting Type 2

Ruffini Endings
- In the Dermis
- Detects skin stretching or constant pressure
- Slow Adapting Type 2

Question 4

What are Muscle Spindles?

Answer 4

is a proprioceptive modality that requires mechanical stretch to fire
- Are responsive to stretch (lengthening and partial shortening)
- Detects RATE OF CHANGE & ABSOLUTE FIBRE LENGTH

Question 5

What is the distrubition of muscle spindles?

i.e where are large amounts vs low amounts

Answer 5

Large amounts in:
- Muscles associated with head and neck movement –> due to keeping the head stable to allow the vestibular system to effectively work
- Muscles associated with trunk and hip –> in relation to postural control
- Muscles spanning across joint areas

Lower amounts in:
- Performing simple movements (e.g. 3rd or 4th finger etc)

Question 6

What kind of efferent signalling increases the sensitivity of muscle spindles?

Answer 6

Gamma efferent neural Signalling

This was from the Lecture Quiz

Question 7

Intensity and timing of muscle spindles

Answer 7

Intensity:
Muscle spindles detect changes in muscle length and the rate of lengthening, providing information on muscle stretch intensity. When a muscle stretches, the muscle spindle fibers are activated, sending signals to the central nervous system about the degree of stretch. The greater the stretch, the higher the firing rate of these spindle afferents, signaling a need for contraction or adjustment in muscle tension.

Timing:
Muscle spindles are highly sensitive to rapid changes, allowing them to respond almost instantly to quick stretches, such as those occurring during sudden movements. This rapid response helps initiate reflexes like the stretch reflex, which acts to counter excessive stretching by causing the muscle to contract, thus stabilizing joints and maintaining posture.