Muscles

Question 1

What muscles are contained in each intercostal space

Answer 1

External intercostal
Internal intercostal
Innermost intercostals

Question 2

When are the external intercostal muscles used

Answer 2

Inspiration

Question 3

When are the internal intercostal muscles used

Answer 3

Forced expiration

Question 4

When are the innermost intercostal muscles used

Answer 4

Forced expiration

Question 5

Direction of fibres of the external intercostals

Answer 5

Inferiorly and anteriorly from above rib to one below

Question 6

Direction of fibres of the internal intercostals

Answer 6

Inferiorly and posteriorly from above rib to one below

Question 7

Action of the external intercostal muscles

Answer 7

Elevates the ribs to increase anteroposterior and transverse diameters of the chest

Question 8

Action of the internal intercostal muscles

Answer 8

Pulls the ribs down from the position of chest expansion

Question 9

What percentage of chest expansion are the external intercostal muscles responsible for

Answer 9

30%

Question 10

Innervation of the intercostal muscles

Answer 10

Intercostal nerves T1-11

Question 11

What is mainly responsible for inspiration

Answer 11

The diaphragm (70%)

Question 12

Where are the openings in the diaphragm

Answer 12

T8 - vena cava
T10 - oesophageal hiatus
T12 - aortic hiatus

Question 13

Innervation of the diaphragm

Answer 13

Phrenic nerve

Question 14

Where is the sensory supply of the phrenic nerve to

Answer 14

Both surfaces of the diaphragm

Mediastinal part of the parietal pleura

Question 15

Parts of the diaphragm and where they arise from

Answer 15

Vertebral - from the crura and arcuate ligaments
Costal - from the inner aspects of 7-12 costal cartilages
Sternal - from the deep surface of the xiphisternum

Question 16

What are the internal and external intercostal muscles continuous with

Answer 16

Respective abdominal wall muscles

Question 17

Where does the right crus arise from

Answer 17

L1-3

Question 18

Where does the left crus arise from

Answer 18

L1-2

Question 19

Which diaphragm dome is higher

Answer 19

Right dome due to presence of the liver

Question 20

How is paralysis of the diaphragm caused

Answer 20

Phrenic nerve lesion due to:
Surgery
Compression by tumour in the chest cavity
Myopathies such as myasthenia gravis 
Neuropathies

Question 21

What happens during ventilation when the diaphragm is paralysed

Answer 21

Paradoxical movement

Affected side moves upwards during inspiration and downwards during expiration

Question 22

Treatment for diaphragm paralysis

Answer 22

1. Underlying cause must be treated

2. Non invasive ventilation e.g CPAP machine (continuous positive airway pressure)