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Respiratory > Muscles Of Respiration > Flashcards

Muscles Of Respiration Flashcards

1
Q

What happens during inspiration?

A

Contraction

Diaphragm - flattens, extending the superior/inferior dimension of the thoracic a cavity

External intercostal muscles - elevates the ribs and sternum superiorly and anteriorly, extending the anterior/posterior dimensions of the thoracic cavity

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2
Q

Define Boyles Law

A

Volume of gas is inversely proportional to pressure

Example
Volume of thoracic cavity increases - volume of lungs increases = pressure within lungs decreases

Volume of thoracic cavity decreases - volume of lungs decreases = pressure within the lungs increases

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3
Q

Does the volume increase in the lungs or decrease as a result of inspiratory muscles?

A

Increase

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4
Q

Does the volume increase in the lungs or decrease as a result of expiratory muscles?

A

Decrease

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5
Q

What is the process of passive expiration?

A

Relaxation

Diaphragm - relaxes returning to resting position, domes superiorly. Reduces superior/inferior dimension of the thoracic cavity

External intercostal muscles - relax to depress the ribs and sternum. Rescues the anterior/posterior dimensions of the thoracic cavity

Internal intercostals - contract. Pull ribs inferiorly, and pull the sternum inferiorly and posteriorly. Decreasing the anterior/posterior lateral dimensions of the thoracic cavity

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6
Q

What is forced breathing?

A

Active mode of breathing which utilises additional muscles to rapidly expand and contract the thoracic cavity volume e.g. during exercise

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7
Q

What is the mode of active inspiration?

A

Contraction of accessory muscles
(Act to increase volume)

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8
Q

What does scalenes muscle do in active inspiration?

A

Elevates the upper ribs

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9
Q

What does sterncleidmastoid muscle do in active inspiration?

A

Elevates the sternum

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10
Q

What does pectoralis major and minor muscle do in active inspiration?

A

Pull ribs outwards

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11
Q

What does serratus anterior muscle do in active inspiration?

A

Elevates the ribs (when the scapulae are fixed)

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12
Q

What does latissimus Doris muscle do in active inspiration?

A

Elevates the lower ribs

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13
Q

What is active expiration?

A

Utilises the contraction of several thoracic and abdominal muscles
(Act to decrease volume of the thoracic cavity)

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14
Q

What does anterolateral abdominal wall do in active expiration?

A

Increase the intra-abdominal pressure, pushing the diaphragm further upwards into the thoracic cavity

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15
Q

What do the internal and innermost intercostal do in active expiration?

A

Depresses the ribs

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16
Q

When does the pressure inside the lung rise?

A

During the expiration phase of breathing

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17
Q

Do muscles contract or relax during expiration?

A

Relax

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18
Q

Do muscles contract or relax during inspiration?

A

Contract

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19
Q

Which nerve provides motor innervation to the diaphragm?

A

Phrenic

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20
Q

What does the scalenes do in active inspiration?

A

Elevate the upper ribs

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21
Q

What does the sternocleidomastoid do during active inspiration?

A

Elevates the sternum

22
Q

What does the pectoralis major and minor do during active inspiration?

A

Pull the ribs outwards

23
Q

What does the serratus anterior do during active inspiration?

A

Elevates the ribs (when the scapulae are fixed)

24
Q

What does the latissimus dorsi do during active inspiration?

A

Elevates the lower ribs

25
Q

What does the anterolateral abdominal wall do during active expiration?

A

Increase the intra-abdominal pressure, pushing the diaphragm further upwards into the thoracic cavity

26
Q

What does the internal intercostal do during active expiration?

A

Depresses the ribs

27
Q

What does the innermost intercostal do during active expiration?

A

Depresses the ribs

28
Q

What are the muscles of active expiration

A

Anterolateral abdominal wall

Internal intercostal

Innermost intercostal

29
Q

What are the muscles of active inspiration?

A

Scalenes

Sternocleidomastoid

Pectoralis major and minor

Serratus anterior

Latissimus dorsi

30
Q

What type of muscle and shape is the diaphragm

A

Broad, thin, domed sheet of skeletal muscle

31
Q

What does the diaphragm separate

A

Thoracic and abdominal cavities

32
Q

What is the superior (thoracic) surface adjacent to

A

Parietal pleura

33
Q

What do apertures in the diaphragm allow

A

Passage of structures between the abdomen and thorax (e.g. the aorta, inferior vena cava and oesophagus)

34
Q

What is the function of the diaphragm

A

Mechanics of breathing (ventilation)

35
Q

Where is the diaphragm attached

A

Xiphoid process
Costal margin (and to the tips of the 11th and 12th ribs)
Lumbar vertebrae

36
Q

What is the central part of the diaphragm

A

Not muscular

Fibrosis = central tendon

37
Q

What innervates the left and right sides of the diaphragm

A

Left and right phrenic nerves

Somatic nerves

Formed in the neck by fibres from the C3, C4 and C5 spinal nerves

Motor and sensory fibres

38
Q

What are the 5 key principles of the mechanics of breathing

A

Muscles move the thoracic cage and change the dimensions of the thoracic cavity

Dimensions of the thoracic cavity determine the intrathoracic volume

Changes in intrathoracic volume alter intrathoracic pressure

Pressure changes inside the thorax drive inspiration and expiration

Different muscles are involved in normal, vigorous and forced ventilation

39
Q

During ventilation what are the three planes that the dimensions the thoracic cavity changes in

A

Vertically - due to contraction and relaxation of the diaphragm

Laterally - due to the contraction of the intercostal muscles which move the ribs

Antero-posteriorly (AP) - due to the movement of the sternum secondary to the movement of the ribs

40
Q

What is the role of the pleural fluid

A

Creates surface tension between the pleura lining the thoracic cavity and the visceral pleura on the surface of the lungs

41
Q

What does surface tension caused by the pleural fluid do

A

Keeps the lungs and thoracic wall together

Between the two pleural membranes keeps them in contact with each other - prevents the lung from collapsing away from the thoracic wall

42
Q

In normal (quiet breathing) what is active and passive

A

Inspiration is active (mainly driven by diaphragm)

Expiration is passive

43
Q

In vigorous breathing (exercise) what muscles become important

A

Intercostal muscles

44
Q

What muscles do active expiration use

A

Internal intercostal muscles

45
Q

In vigorous or forced breathing (e.g. exacerbation of asthma) what muscles contribute

A

Accessory muscles

46
Q

What are the accessory muscles

A

Sternocleidomastoid
Pec major
Pec minor
Serratus anterior

47
Q

What is involved in inspiration

A

Diaphragm contracts

External intercostals

48
Q

What is involved in expiration - passive

A

Diaphragm relaxes

External intercostals relax

49
Q

What are the muscles of active inspiration

A

Scalenes

Sternocleidomastoid

Pectoralis major and minor

Serratus anterior

Latissimus dorsi

50
Q

What are the muscles of active expiration

A

Anterolateral abdominal wall

Internal intercostals

Innermost intercostals

Respiratory (16 decks)

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