Neurology Stretch Reflex

Question 1

Stretch Reflex

Answer 1

Muscle Spindle Reflex

Question 2

Extrafusal Fibers

Answer 2

Attached to tendons and generate movement
When they contract they pull on tendon which pulls on bone

Question 3

Connective Tissue Capsule

Answer 3

Encloses Intrafusal muscle fibers (Proprioceptors - tells you the position of muscle, tendons, ligament, joints in 3D space)

Question 4

A bunch of intrafusal fibers

Answer 4

Muscle Spindles

Question 5

Intrafusal Fibers

Answer 5

Pick up degree of stretch and speed of stretch (length and velocity)

Question 6

Other intrafusal fibers

Answer 6

Nuclear bag fibers and Nuclear chain fibers
When they’re stretched it causes the little nerve fibers wrapped around to be stretched and activate Na channels in nerve endings

Question 7

Nuclear Bag Fibers

Answer 7

They’re larger than the Nuclear chain fiber; Centrally localized nuclei
They pick up and more sensitive to length and velocity

Question 8

Nuclear Chain fiber

Answer 8

More sensitive to ONLY length
Nuclei are arranged in chain like fashion

Question 9

Type 1A fibers or Anulospinal Endings

Answer 9

The fibers that pick up degree of stretch

Question 10

Type 2 fibers or flower spray endings

Answer 10

They are only found Nuclear chain fibers
Pick up sensory information

Question 11

On the polar fibers at the end has

Answer 11

Actin and Myosin

Question 12

What Nerve stimulates the contraction at the ends of Intrafusal fibers

Answer 12

Grammar Motor neurons; Motor supply to the intrafusion muscle fibers

Question 13

When the sensory fibers stretch it stimulates

Answer 13

Mechanically gated Ion channels causing Na to flow in from the extracellular to intracellular making cell more positive. causing the resting membrane potential to threshold potential. When the threshold voltage is reached, it activates the Voltage gated ion channels. They only open at a specific voltage. Positive ions generates action potential

Question 14

Type 1A and Type 2 fibers

Answer 14

pick up sensation of stretch and they will travel to dorsal root. There they synapse directly to a motor neuron or little motor neuron. The motor neuron causes the muscle to contract

Question 15

One sensory neuron to one sensory neuron

Answer 15

Ipsilateral Monosynaptic reflec

Question 16

Sensory neuron can act on a little neuron called

Answer 16

Interneuron inhibits motor neurons. The inhibit muscle contraction while the quadriceps muscle contracts it

Question 17

Reciprocal Inhibition

Answer 17

The contain alpha motor neuron

Question 18

The type 1a and 2 fibers

Answer 18

Sends sensory impulse to sensory fibers or synapse to inter neurons which stimulates the gamma motor neurons who are going to stimulate muscle spindle to contract

Question 19

Corticospinal Tracts

Answer 19

They contain upper motor neurons can synapse and modulate the activity if motor neurons; corticospinal neurons have inhibitory to gamma motor neurons.If their is a lesion, gamma hyper fires causing hypertonia/spasticity

Question 20

Alpha motor neuron

Answer 20

Stretch muscles —> activates EFF and IFF—> type 1 and 2 fibers—> send AP quickly

Question 21

IFF not stretch,

Answer 21

Type 1 A fibers are going to have very little AP. The type 1A is slack and will not open mechaniocally gated channels
EFF and IFF to contract.

Question 22

Alpha Gamma Co activation

Answer 22

GMN to stimulate the IFF to contact so we are sending proper signals