MMB [002] Reflexes

Question 1

Mention the three main components of the motor system (motor levels )

Answer 1

Question 2

The ‘Higher Motor Level ’ represents :

Answer 2

Association areas in the cortex (Idea)

Question 3

The ‘Middle Motor Level ’ represents :

Answer 3

Motor cortex, Basal Ganglia and Cerebellum (Program)

Question 4

The ‘Lower Motor Level ’ represents :

Answer 4

Spinal cord and brain stem nuclei (performance)

Question 5

The 1st Requirement for voluntary contraction :

1) Intact Upper motor neuron (from higher centers to …(), OR to …())

Answer 5

1) Intact Upper motor neuron (from higher centers to the spinal cord, OR to nuclei of cranial nerves)

Question 6

The 2nd Requirement for voluntary contraction :

2) Intact lower motor neuron (from …() of spinal cord to the muscle, OR from …() to muscle)

Answer 6

2) Intact lower motor neuron (from anterior horn of spinal cord to the muscle, OR from cranial nerve nuclei to muscle)

Question 7

The 3rd Requirement for voluntary contraction :

Answer 7

3-intact muscle

Question 8

The 1st Requirement for reflex contraction ?

Answer 8

1- intact muscle

Question 9

The main 2 Requirements for reflex contraction :

Answer 9

1- Intact lower motor neuron (from anterior horn of spinal cord to the muscle , OR from cranial nerve nuclei to muscle)

2- Intact pathway of a reflex arc

Question 10

Illustrate the reflex pathway

Answer 10

sensory receptor > afferent nerve > integrating center > efferent nerve
> effector organ

Question 11

Illustrate the reflex arc

Answer 11

(1) Stimulus

(2) Receptor
(sensory neurone)

(3) CNS motor neurone

(4) Effector Reflexes

(5) Response

Question 12

The 2 types of reflexes ?

Answer 12

1) Protective
2) Regulatory

Question 13

Mention Examples of protective reflexes

Answer 13

Eye blink , gag reflex , limb withdrawal

Question 14

Mention Examples of Regulatory reflexes

Answer 14

Vestibulo–ocular reflex , muscle stretch reflex

Question 15

Two types of motor neurons in the anterior horn ?

Answer 15

Alpha & Gamma

Question 16

Alpha motor neurons supplies …. Skeletal muscle fibers.

Answer 16

Ordinary

Question 17

α-motor neurons mainly originate from… sements (spinal segments)

Answer 17

Cervical and lumbosacral

Question 18

In the thoracic segments below T1, the α-motor neurons are associated only with …(anatomical aspect) muscle

Answer 18

axial

Question 19

Impulses in α-motor neuron are controlled by impulses coming from :

Answer 19

1- Sensory neurons in dorsal root ganglia

2- Interneurons inside the spinal cord gray matter

3- Descending fibers from higher brain centers (e.g. brain stem)

Question 20

The Motor Unit Includes … motor neuron(s) and the contacting muscle fibres

Answer 20

Single motor neuron

Question 21

In a small motor units the motor neuron is with …(degree) threshold of stimulation

Answer 21

LOW

Question 22

In large motor units is the motor neuron with ….(degree) threshold of stimulation

Answer 22

HIGH

Question 23

The total motor neurons projection to a single muscle is called the ….

Answer 23

The Motor Neuron Pool

Question 24

Explain Proprioception

Answer 24

-feedback for the motor control system

-Changes in muscle length specifically stretch – detected by the muscle spindle

-Changes in muscle tension detected by the Golgi tendon organ

Question 25

Changes in muscle length specifically stretch are detected by the ….

Answer 25

muscle spindle

Question 26

Changes in muscle tension are detected by the ….

Answer 26

Golgi tendon organ

Question 27

The muscle stretch reflex – a simple monosynaptic reflex driven by input from the ….

Answer 27

muscle spindle

Question 28

Define Stretch reflex

Answer 28

It is reflex contraction of a muscle in response to its stretch.

Question 29

Stretch reflex is a ….(-VE/+VE)feedback reflex that returns the muscle back to its normal length when stretched.

Answer 29

—VE

Question 30

The Receptor of Stretch reflex is …

Answer 30

The Muscle spindle

Question 31

….(reflex) is the only monosynaptic reflex in the body. AKA : direct contact between afferent & efferent

Answer 31

Stretch reflex

Question 32

What’s the Muscle spindle :

Answer 32

-Specialized encapsulated mechanoreceptor that monitors muscle length

Question 33

The ends of the Muscle spindle’s capsule are attached to the … of the muscle

Answer 33

Tendon

Question 34

The Muscle spindle Consists of ….. fibers parallel to …. fibers

Answer 34

3-10 intrafusal fibers parallel to ordinary contractile fibers

Question 35

Mention the two types of Intrafusal fibers :

Answer 35

- nuclear bag fibers - nuclear chain fibers

Question 36

number of nuclear bag fibers ?

Answer 36

1-3

Question 37

number of nuclear chain fibers in muscle spindles ?

Answer 37

3-9 in each spindle.

Question 38

Intrafusal fibers have …. receptor at stretchable part ,,, and …., non receptor part.

Answer 38

Central receptor at stretchable part ,,, Peripheral contractile, non receptor part.

Question 39

Compare in terms of : -response to stretch - contractility -afferents/efferents

Answer 39

Question 40

Question 41

Question 42

Case 2 Mrs. Stewart is a thirty-year-old woman presents to the ER with excessive sweating, tachycardia and tremors. She is diagnosed as hyperthyroidism, on examination she has exaggerated reflexes and Hypertonia. 1-Define Muscle tone. 2) 2-define tendon jerk.

Answer 42

1) A state of tension that is maintained continuously-minimally even when relaxed and which increases in resistance to passive stretch. 2) A reflex contraction of the muscle to which a tendon is attached when the tendon is struck sharply soas to exert a sudden pull on the muscles

Question 43

Nerve root of Biceps reflex

Answer 43

C5

Question 44

Nerve root of Brachioradial (supinator) reflex

Answer 44

C6

Question 45

Nerve root of Triceps reflex

Answer 45

C7

Question 46

At a reflex rated with +++ , the comment should be :

Answer 46

Slight hyperflexia

Question 47

At a reflex rated with (++++) , the comment should be :

Answer 47

Very brisk, hyperactive

Question 48

Nerve root of Knee reflex

Answer 48

L2, L3 & L4

Question 49

Nerve root of Ankle reflex

Answer 49

S1

Question 50

Answer 50