Mechanorecpters Flashcards
What is the function and behavior of a ruffini corpusles
type I’s
- provide dynamic and static afferents about angle, velocity and amplitude of joint displacement
- slow adapting
- inhibit free nerve endings at the DH for 3-5 minutes
- remain active for up to one minute
- active in the beginning and end range of collagen tension
- tonic musculature
What is the function and behavior of a pacinian corpuscle?
type II’s
- provide dynamic afferents
- fast adapting
- inhibit pain via DH
- remain active for 0.5 seconds
- active in beginning and mid range of collagen tension, do not respond to stretch
- phasic musculature
What is the function and behavior of a free nerve ending?
Type IV’s
- pain provoking triggering four neurologic responses to pain
- non-adapting
- high thresholds
- segmental inhibition
What is the function and behavior of the GTO?
- very slow adapting
- reflex inhibition or facilitation of muscle tone via H-relfex
- recruites other muscles and accounts for a 3-5 fold increase in muscle tension with eccentrics
- Resond to end range of collagen tension
- reflexogenic in nature only and does not influence perceptual motion
Where will you find Ruffini corpuscles?
type I’s
- superficial layers of all joints capsules
- most predominate in neck, hips and shoulders
- located in both muscular and tendonis sites
What mechanoreceptors are most predominate in the lumbar, foot, hand, jaw and feet
Type IIs or pacinian corpuscles
where are pacinian corpuscles located?
type II’s
- deep layers of joint capsule of all joints
- predominate in the hands, feet, lumbar spine and jaw
- more frequent in the teondon and less frequent in the muscle
Where do you tend to find GTOs?
type III’s
- deep and superficial layers of joints and ligaments
- superfiscial layers of the lumbar spine capsules
Where do you find free nerve endings?
- joint capsules
- blood vessels
- articular fat pads
- anterior dura mater
- connective tissue
Where won’t you find free nerve endings?
- muscle
- articular cartilage
- primary nervous tissue, but it is in the surrounding connective tissue and vasculature
What is the refractory period for Type I and II mechanoreceptors?
type I-fires for up to one minute and then requires one minute to reset
type II- fires for about 0.5 seconds and takes about 0.5 seconds to reset
What are the normal thresholds for trigger type IV mechanoreceptors?
- gerater than 3% stretch
- greater than 44.8 C or 112 F
- chemical levels outside normal ranges
How can you rule out muscle weakness due to free nerve ending inhibition?
inhibit the inhibition
Which mechanoreptors are most dominate in the hip neck and shoulders?
Type I or ruffini
What factors contribute to the low threshold for type I mechanorecptors
- it has only a single layer of collagen surrounding it
2. located in the superficial layers of the joint capsule
What regions of the brain do type I’s project to?
- paracentral
2. parietal
What part of the brain do type II’s project to?
- they don’t
2. they are not involved in perceptual awarenss
What chemicals will activate the nocioceptive system?
Most -> least
- Lactic acid
- Potassium ions
- 5-hydroxytrypatmine
- polypeptide kinins
- prostaglandins
- histamine
what are the primary chemical irritants released during ischemia and inflammation?
ischemia 1.lactic acid 2.potassium ions inflammation 3.5-hydroxytrypatmine 4.polypeptide kinins 5.prostaglandins 6.histamine
How come arthritis is painful if cartilage has no free nerve endings?
- joint inflammation increases tension on the capsule and irritates the synovium
- decrease shock absorbing capacity transmits more force to the subcondral bone
- ingrowth of capillaries with free nerve ending, so even after recovering the loss of the granulation tissue you are left with the free nerve endings
What is the speed and myelin content of the four basic mechanorecptors?
- type Is or ruffini- 15-40 ms, thin
- type II’s or pacinian- 40-70 ms, medium
- type III’s or GTO- 70-120 ms, thick
- type IV’s or fne
a-delta- 5-15 ms, thing
B -3-14 ms, none
C 0.02-2 ms, none
How is the perception of A-Delta and C fiber free nerve endings different?
- A-delta- sharp fast
2. C- deep burning
