20- Muscle reflexes

Question 1

What do nociceptors sense?

Answer 1

pain and tempterature

Question 2

Name 2 types of mechanoreceptors

Answer 2

pacinian corpuscles (vibration), Meissner corpuscles (touch)

Question 3

What do muscle spindles sense?

Answer 3

length of the muscle and the rate of change length

Question 4

What do golgi tendon organs sense?

Answer 4

tension, rate of change of tension

Question 5

What do ruffini end organs sense?

Answer 5

joint angle

Question 6

What are the 4 functions of muscle spindles?

Answer 6

Mediate response to load
Dampening function- Prevent jerkiness in body movements
Invoked in voluntary motor activity
Maintain posture

Question 7

Where are muscle spindles?

Answer 7

buried among the extrafusal fibers of the muscle

Question 8

What type of nerves send afferent information of rate of muscle change?

Answer 8

type 1a afferent

Question 9

What type of nerves send afferent information of spindle tension and efferent information to the intrafusal fibers?

Answer 9

gamma motor neurons

Question 10

What type of nerves send afferent information of muscle tension and efferent innervation of extrafusal fibers?

Answer 10

alpha motor neurons

Question 11

What are the types of afferent fibers of stretch that attach to the nuclear chain fibers but not to the nuclear bag fibers?

Answer 11

Type II afferent

Question 12

What are nuclear chain fibers?

Answer 12

Nuclear chain fibers are intrafusal fibers which, along with nuclear bag fibers, make up the muscle spindle responsible for the detection of changes in muscle length

Question 13

What is a nuclear bag fiber?

Answer 13

A nuclear bag fiber is a type of intrafusal muscle fiber that lies in the center of a muscle spindle. Each has a large number of nuclei concentrated in bags and they cause excitation of both the primary and secondary nerve fibers

Question 14

what is a gamma loop?

Answer 14

mg forces/micron contractions in spindle control

kg forces/cm contractions in the muscles

Question 15

What is a stretch/myotactic reflex?

Answer 15

Reflex contraction of a muscle when an attached tendon is pulled

Question 16

What is an example of the monosynaptic myotactic reflex?

Answer 16

patellar reflex

Question 17

What fibers are involved with the patellar reflex?

Answer 17

muscle spindle stretched –> Ia sensory nerve activated –> stimulates alpha MN of quads –> interneuron inhibits hamstrings (antagonist)

Question 18

What do gamma efferent nerves do?

Answer 18

Keeps muscle spindle sensitive to any stretch. When the muscle contracts, the gamma MN will be activated in order to maintain the sensitivity of the muscle spindle (alpha-gamma co-activation)

Question 19

What does OMT do to gamma gain?

Answer 19

decrease it

Question 20

What is the lengthening reflex?

Answer 20

In the lengthening reflex excessive tension inhibits (lengthens) the muscle associated with the Golgi tendon organ.

Question 21

What do golgi tendon organs do?

Answer 21

Prevents muscle contraction
Type Ib sensory (afferent) fibers origin
Inhibit alpha motor neuron (polysynaptic)
Stimulates gamma efferents to reset muscle tone
Relaxes a muscle after a sustained contraction (muscle energy technique)
Decreases tension in tendons

Question 22

How is the muscle protected from excessively heavy loads?

Answer 22

The golgi tendon reflex causes the muscle to relax and drop the load.

Question 23

What happens when you stretch your muscles and hold?

Answer 23

The muscle spindle gets accustomed to the new length (habituates) and signals less

Question 24

What do joint receptors trigger?

Answer 24

Secretion of synovial fluid
Production of glycosaminoglycans and possibly other joint macromolecules
Increased blood and lymph flow to/from joint