Lecture 5: Applied anatomical concepts Flashcards
What are the two types of breathing?
Thoracic and abdominal
What is the effect of inspiration on volume and pressure in the thorax?
Increase in intra-thoracic diameter/volume
Decrease in intra-pleural pressure
What are the three changes in dimension that occur during inspiration?
Lateral/Transverse diameter
Anterior Posterior diameter
Vertical diameter
Describe the change to the lateral diameter of the thorax during inspiration?
Lateral edges of ribs are elevated supero-laterally and the lateral diameter of thoracic cavity increases
Results in an increase in the transverse diameter of chest cavity
Bucket handle movement
Describe the change to the anterior/posterior diameter of the thorax during inspiration?
Anterior ends of ribs are raised during inspiration
Elevation causes sternum to also be raised
Movement is facilitated by costal cartilages
Results in an increase in antero-posterior diameter of chest cavity
Pump handle movement
What is the effect of expiration on volume and pressure in the thorax?
Decrease in intra-thoracic diameter/volume
Increased intra-pleural pressure results in air being expelled from lungs
When is forced (active) expiration required?
Coughing
Playing wind instruments
Exertion
What muscles are used for quiet inspiration?
External intercostals
Scalene muscles
Plus the diaphragm
What muscles are used for quiet expiration?
Passive
What muscles are used for forced inspiration?
External intercostals
Scalene muscles
Plus the diaphragm
AND
Pectoral muscles
Sternocleidomastoid
Latissimus dorsi
What muscles are used for forced expiration?
Internal intercostals
Oblique and transverse abdominal muscles
Quadratus lumborum
How do you increase the vertical diameter of the thorax?
Via diaphragm which forms floor of thoracic cavity
Descends upon contraction up to 5 -10 cm compressing abdominal organs
↑ vertical diameter of thorax
What is abdominal breathing?
When the diaphragm in contracted
Reduced during pregnancy
What is the diaphragm?
Sheet of skeletal muscle with a central tendon
What is attached to the middle of the tendon on the superior surface of the diaphragm?
The pericardium
What lines the superior surface of the diaphragm?
Diaphragmatic parietal pleura
What are the three sections of the diaphragm?
Sternal
Costal
Lumbar
Describe the sternal part of the diaphragm.
2 muscular slips sometimes leaving the anteromedian gap
Describe the costal part of the diaphragm.
From inferior 6 costal cartilages
Describe the lumbar part of the diaphragm.
Part that gives rise to the medial and lateral arcuate ligaments and is anchored by the musculotendinous right and left crura
What is the diaphragm used for?
Coughing, laughing, urinating and defecation, lifting heavy objects (braces vertebral column)
What are the three openings in the diaphragm?
Opening for Inferior Vena Cava
Oesophageal hiatus
Aortic hiatus
What provides the blood supply of the diaphragm?
Superior & inferior phrenic arteries
Where do the phrenic nerves originate?
C3, C4, C5
What gets sensory supply from the phrenic nerve?
Pericardium
Parietal pleura (mediastinal and diaphragmatic – central only)
Parietal peritoneum
Central region of diaphragm
What gets motor supply from the phrenic nerve?
Diaphragm (sole supply)
Where does the phrenic nerve enter the superior mediastinum?
Lateral to the Vagus nerve
Describe the pathway of the right phrenic nerve.
Passes on right wall of SVC to right side of pericardium, descends on pericardium over right atrium to diaphragm (near IVC orifice)
Describe the pathway of the left phrenic nerve.
Runs over aortic arch and pulmonary trunk, descends on pericardium over left ventricle to diaphragm (near cardiac apex)
What regulates the SA node?
Autonomic nerves via the Cardiac Plexus
Parasympathetic fibres - Vagus nerve
Sympathetic fibers - T1-5 levels of spinal cord and associated paravertebral ganglia
What is a phancoast tumour?
Cancer located at apex of the lung
If on left side can cause recurrent laryngeal nerve compression
Vocal cord paralysis = Hoarseness
What is used to locate left vagus nerve?
Ligamentum arteriosum
