Muscles Flashcards
What muscles are contained in each intercostal space
External intercostal
Internal intercostal
Innermost intercostals
When are the external intercostal muscles used
Inspiration
When are the internal intercostal muscles used
Forced expiration
When are the innermost intercostal muscles used
Forced expiration
Direction of fibres of the external intercostals
Inferiorly and anteriorly from above rib to one below
Direction of fibres of the internal intercostals
Inferiorly and posteriorly from above rib to one below
Action of the external intercostal muscles
Elevates the ribs to increase anteroposterior and transverse diameters of the chest
Action of the internal intercostal muscles
Pulls the ribs down from the position of chest expansion
What percentage of chest expansion are the external intercostal muscles responsible for
30%
Innervation of the intercostal muscles
Intercostal nerves T1-11
What is mainly responsible for inspiration
The diaphragm (70%)
Where are the openings in the diaphragm
T8 - vena cava
T10 - oesophageal hiatus
T12 - aortic hiatus
Innervation of the diaphragm
Phrenic nerve
Where is the sensory supply of the phrenic nerve to
Both surfaces of the diaphragm
Mediastinal part of the parietal pleura
Parts of the diaphragm and where they arise from
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
What are the internal and external intercostal muscles continuous with
Respective abdominal wall muscles
Where does the right crus arise from
L1-3
Where does the left crus arise from
L1-2
Which diaphragm dome is higher
Right dome due to presence of the liver
How is paralysis of the diaphragm caused
Phrenic nerve lesion due to: Surgery Compression by tumour in the chest cavity Myopathies such as myasthenia gravis Neuropathies
What happens during ventilation when the diaphragm is paralysed
Paradoxical movement
Affected side moves upwards during inspiration and downwards during expiration
Treatment for diaphragm paralysis
- Underlying cause must be treated
2. Non invasive ventilation e.g CPAP machine (continuous positive airway pressure)
