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M&M Physiology > Muscle Tone & Reflexes > Flashcards

Muscle Tone & Reflexes Flashcards

1
Q

Muscle tone definition :

A

Mild maintained reflex contraction during rest

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2
Q

Distribution of muscle tone

A

Found in all skeletal muscles but more in antigravity muscles

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3
Q

Antigravity muscles ?

A

Muscles that support body weight.

Extensors in LL,Trunk and neck
Flexors in UL and elevators of jaw

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4
Q

Mechanism of muscle tone

A

Stretch reflex

Length of the muscle is shorter than the distance between origin and insertion

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5
Q

Stretch reflex definition

A

Stretch of skeletal muscle leads to feedback contraction of it

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6
Q

Pathway of stretch reflex

A

1- Stimulus
2- Receptor : muscle spindle
3- Afferent : Primary and secondary endings > Posterior root of spinal cord
4- Center : AHC
5- Efferent : Alpha motor neuron to extrafusal muscle fibers
6- Effector organ
7- Response

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7
Q

Intrafusal muscle fibers types

A 
Nuclear bag (1-2 in each spindle)
Nuclear chain (3-9 in each spindle)
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8
Q

Characters of nuclear bag

A

Rapidly response
Rapidly adapting
Their nuclei collected in the center

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9
Q

Characters of nuclear chain

A

Spread throughout the central receptor area
Slowly responding
Slowly adapting

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10
Q

Which type of fibers of skeletal muscles are not contractile

A

Intrafusal muscle fibers

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11
Q

Types of afferent fibers from muscle spindle

A

Primary ending

Secondary ending

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12
Q

Characters of primary ending afferent fibers

A

Spiral around nuclear bag and nuclear chain
Group A alpha neurons
Respond first
Responsible for both types of stretch reflex

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13
Q

Characters of secondary ending afferent fibers

A

Originate from nuclear chain
Group A beta neurons
Responsible for static stretch reflex

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14
Q

The efferent innervation of muscle spindle

A

Group A gamma from small AHC that receives impulses from supraspinal centers

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15
Q

Ways of stimulation muscle spindles

A

Stretch of the whole muscle

Increased gamma efferent discharge

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16
Q

Types of stretch reflex

A

Dynamic

Static

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17
Q

Dynamic stretch reflex occurs with the ……….. not ………….. stretch

A

Sudden | maintained

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18
Q

Stimulus of dynamic stretch reflex

A

The start of a long stretch

Sudden not maintained stretch

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19
Q

Receptor of dynamic stretch reflex

A

Nuclear bag

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20
Q

Afferent of dynamic stretch reflex

A

Primary ending only

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21
Q

Function of dynamic stretch reflex

A

Tendon jerks

22
Q

Static reflex occurs as ……. as the stretch is ……………

A

Long | maintained

23
Q

Stimulus of static stretch reflex

A

Maintained stretch

24
Q

Receptors of static stretch reflex

A

Nuclear chain

25
Q

Afferent in static Stretch reflex

A

Mainly secondary endings and also primary endings

26
Q

Function of static stretch reflex

A

Muscle tone

27
Q

Functions of gamma efferents

A

1- Adjusting the muscle tone

2- Co-activation with A-motor neurons

28
Q

How does gamma efferents adjust muscle tone

A

Descending stimulatory impulses through it > Contraction in peripheral contractile parts > Stretch of the receptor > Reflex muscle contraction

29
Q

Benefits of Co-activation of gamma motor neurons with A-motor neurons

A

Potentiate the voluntary movement

Keep the muscle spindle sensitive even during contraction

30
Q

Higher centers that stimulate stretch reflex

A 
Area 4
Caudate nucleus 
Neocerebullum 
Facilitatory reticular formation
Vestibular nucleus
31
Q

Higher centers that inhibit stretch reflex

A 
Area 6
Lentiform nucleus
Paleocerebullum
Inhibitory reticular formation
Red nucleus
32
Q

Clinical importance of stretch reflex

A

1- Muscle tone
2- Tendon jerks
3- Role in voluntary movement
a- potentiation b- damping

33
Q

Tendon jerks definition

A

Sudden brief contraction in muscle after tapping it’s tendon

34
Q

Mechanism of tendon jerks

A

Dynamic stretch reflex

35
Q

Diagnostic value of tendon jerks

A

Increased in
UMNL
Hyperthyroidism
Nervousness

Deceased or absent in
LMNL
Hypothyroidism
Sleep

36
Q

Plantar reflex center

A

S1

37
Q

Stimulation of plantar reflex

A

Firm scratching of the lateral side of the sole from behind forward

38
Q

Normal response of plantar reflex

A

Flextion of all toes

39
Q

Abnormal response to plantar reflex

A

Dorsiflexion of big toe and fanning of the others (Babinski’s sign)

40
Q

Causes of abnormal plantar reflex

A 
Physiological: 
Deep sleep
Deep come
General anesthesia
Infants below 1 year

Pathological : UMNL

41
Q

Abdominal reflex center

A

T8-T12

42
Q

Abdominal reflex stimulation

A

Gentle scratching of the skin of the four quadrants of the abdominal using pointed object towards the midline

43
Q

Normal response of abdominal reflex

A

Contraction of underlying muscles of the abdominal wall

44
Q

Abnormal response of the abdominal reflex

A

Absent of contraction of underlying

45
Q

Pathological Causes of absence of abdominal reflex

A

UMNL

LMNL affecting the reflex arc

46
Q

Physiological Causes of absence of abdominal reflex

A

weakness of the muscles

Obesity
Multiparous women

47
Q

Golgi tendon reflex definition

A

Severe contraction > Relaxation

48
Q

Function of Golgi tendon reflexe

A

Prevents rupture of the tendon

49
Q

Pathway of golgi tendon reflex

A

Stimulus: Marked muscle contraction (Severe stretch of the tendon)
Receptor: Golgi tendon organ (in the tendon)
Afferent: A alpha
Center: Polysynaptic > Glycine > Hyperpolarization of AHC
Efferent: A alpha
Response: muscle relaxation

50
Q

Effects of hypersensitivity of muscle spindle on muscle tone

Clasp-knife spasticity

A

Condition in which during examination of muscle tone the muscle tone will gradually increase then sudden disappear near the end

51
Q

Flexion withdrawal reflex definition

A

Painful stimulus applied to a limb will lead to flextion of it away from the pain

52
Q

Crossed extensor reflex definition

A

Painful stimuli applied to a limb leads to flexion and withdrawal of it and extension of the same limb on the other side to support body weight

M&M Physiology (4 decks)

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