L9 Stabilization

Question 1

The simplest manifestation of muscle
spindle function is?

Answer 1

the muscle stretch
reflex.

Question 2

muscle spindle receptor can be excited in two ways:

Answer 2

1- stretch of mid portion
2- contraction of end portion

Question 3

Center of stretch reflex ?

Answer 3

Anterior horn cell of spinal cord

Question 4

-Two types os sensory ending

Answer 4

Primary
secondary

Question 5

Afferent of stretch reflex

Answer 5

• type Ia proprioceptor nerve
  fiber originating in a muscle spindle and
  entering a dorsal root of the spinal cord (center).

Question 6

Efferent of stretch reflex

Answer 6

– anterior motor (spinal)
supplying extrafusal/agonistic muscle

Question 7

Efferent of stretch reflex ?

Answer 7

Anterior alpha fibers to ( extrafusal muscle fibers )

Gamma stretch alpha تشد على الاطراف

Question 8

1. Muscle spindles- are

Answer 8

present belly of the muscle and send information to the nervous system about muscle length or rate of change of length, and

Question 9

• Afferent primary fiber Type IA( Aa ) Properties

Answer 9

Annulospiral
Larger
Encircles central portion of intrafusal

Question 10

Muscle spindle in stretch reflex number of synapses?

Answer 10

Monosynaptic

Question 11

gamma motor nerve fibers that originate from

Answer 11

small type A gamma motor
neurons in the anterior horns of the spinal cord

Question 12

most important functions of the muscle spindle system is to

Answer 12

stabilize body position during tense motor action.

Question 13

How Muscle spindle system stabilizes body position during tense action?

Answer 13

هذا الفسيليتيشن اللي يصير
bulboreticular facilitatory region
ترسل

signals through the gamma nerve fibers to intrafusal

shortens the ends

stretches the central

increasing output

Question 14

if the spindles on both sides of each joint are activated at the
same time what happen?

Answer 14

reflex excitation of the skeletal muscles on both sides of the joint increases,

producing tight, tense muscles opposing each other joint

Then the position of the joint becomes strongly stabilized,

Question 15

2- Golgi tendon organs ( inverse stretch reflex ):

Answer 15

-Polysynaptic
-located in the muscle tendons and
-transmit information about tendon tension or rate of change of tension.

-has both a dynamic response and a static response

-transmit signals both
into local areas of the cord and

-Dorsal horn

-spinocerebellar tracts

-rapidly conducting type Ib
nerve fibers

-inhibitory interneuron that inhibits the anterior motor neuron.

-local circuit directly inhibits the individual muscle without affecting adjacent muscles.

Question 16

Role of the muscle spindle in voluntary motor activity

Answer 16

keeps the length of the receptor portion of the muscle spindle from changing

maintains the proper damping
function of the muscle spindle

Question 17

Significants of muscle or knee joint

Answer 17

1- assess degree of facilitation to SC
2- determine presence of spasticity
3- if facilitation inc. reflex exaggerated
4- if facilitation dec. reflex depressed

Question 18

-lesion ( stroke) of upper motor area will do what in muscle jerk?

Answer 18

Exaggerated muscle jerk in opposite side of the body