Skeletal Muscle Organ Reflex

Question 1

Exteroceptors

Answer 1

Surface of the body and sensitive to external environment
Pain, pressure and touch

Question 2

Proprioceptors

Answer 2

Muscle, tendons, joints and in the inner ears and sensitive to movement
Perceives where the body is located (standing, sitting, etc.)
Sense of space

Question 3

Interoceptors

Answer 3

Located in the viscera of the body and sensitive to changes in the internal environment
pH change, stomach cramping

Question 4

Muscle spindles

Answer 4

In parallel to the contracting skeletal muscle fibers
Detects muscle length
Sensory organ inside muscle fibers

Question 5

Golgi tendon organ

Answer 5

Arranged in series with the contracting skeletal muscle fibers
Detects muscle tension
Reflex through alpha motor neurons

Question 6

Muscle spindle sensory innervation

Answer 6

Ia afferent nerve
Group II afferent nerves

Question 7

Ia afferent nerve (sensory innervation)

Answer 7

Innervates the central region of both the nuclear bag fibers
Synapses on alpha motor of extensor

Question 8

Group II afferent nerves (sensory)

Answer 8

Innervates the nuclear chain fibers

Question 9

Muscle spindle motor innervation

Answer 9

Contractile end regions innervated by gamma efferent fibers that maintain spindle sensitivity
Synapse on interneurons that are inhibitory to flexors

Question 10

Alpha- gamma coactivation

Answer 10

1. Alpha motor neuron fires and gamma motor neuron fires
2. Muscle contracts
3. Stretch on centers of intrafusal fibers unchanged
   firing rate of afferent neuron remains constant

Question 11

Contraction without gamma motor neurons

Answer 11

1. Alpha motor neuron fires
2. Muscle contracts
3. Less stretch on center of intrafusal fibers
4. Firing rate of spindle sensory neuron decreases

Question 12

Reflex arc

Answer 12

An involuntary response of the nervous system to a stimulus
Fixed motor response to a sensory stimulus mediated through specific neuronal linkages

Question 13

What are the 5 components of a reflex arc?

Answer 13

1. receptor
2. sensory neuron
3. one or more synapses in CNS
4. motor neuron
5. target organ, usually a muscle

Question 14

Reciprocal innervation

Answer 14

Seen in knee jerk
Excite flexors
Inhibits extensors

Question 15

Crossed- extensor reflex (part of the withdrawal reflex)

Answer 15

Serves postural function
Extension of contralateral limb to support animal when an extremity is flexed
Polysynaptic
Double reciprocal innervation

Question 16

What does biceps reflex test?

Answer 16

Sensory and motor components
Musculocutaneous nerve
C6 and C7 spinal nerve

Question 17

What does triceps reflex test?

Answer 17

Sensory and motor neurons
Radial nerve
Spinal cord segments C7, C8, T1`

Question 18

Cranial Tibial Reflex

Answer 18

Tests integrity of SC segments L6 to S2
Sciatic and peroneal nerves

Question 19

Perineal reflex

Answer 19

Light stimulation of perineum with forceps
Tests function of sacral SC segments and associated nerve roots

Question 20

What is the response of the perineal reflex?

Answer 20

Contraction of anal sphincter and flexion of tail