The Mediastinum Flashcards
What area does the Mediastinum cover?
Extends from:
- Thoracic inlet/aperture
- Diaphragm
- Sternum & costal cartilages
- Thoracic vertebrae
What is the function of the mediastinum?
The mediastinum allows for movement of the lungs, heart and great vessels and protects them
What great vessels are in the superior mediastinum?
- Aorta (arch and descending)
- Left and right common carotid
- left and right subclavian
- Brachiocephalic trunk
What nerves are in the superior mediastinum?
- Phrenic(C3, 4, 5) provides motor to diaphragm and sensory to pericardium mediastinal pleura
- Recurrent Laryngeal loops under arch and right subclavian to innervate larynx
- Vagus (CN X) innervated heart, oesophagus and bronchi
What veins are in the superior mediastinum?
- Superior vena cava
- Brachiocephalic
What other structures are in the superior mediastinum?
- Oesophagus
- Thoracic duct
- Thymus gland
- Lymphatic trunks
What structures are the in inferior mediastinum?
- Heart
- Inferior vena cava
- Oesophagus
- Descending aorta
What structures are in the anterior mediastinum?
Thymus gland
What structures are in the middle mediastinum?
- Heart
- Pericardium
What structures are in the posterior mediastinum?
- Primary Bronchi
- Descending aorta
- Azygos and Hemi Azygos veins
- Thoracic duct
- Oesophagus and oesophageal plexus
What are the results of phrenic nerve paralysis?
Elevation of the ipsilateral hemidiaphragm
What spinal levels does the trachea extend across?
C6-T4
What is the bifurcation of the trachea known as?
Carina - bifurcation into primary bronchi at the transthoracic plane
Where is the oesophagus positioned?
- immediately posterior to the trachea
- inclines to the left but is compressed by the aortic arch and the root of the left lung root
What is the outer layer of the pericardium called and what is it’s function?
Fibrous pericardium
- stabilises the heart and prevents overdilation
What is the inner layer of the pericardium called and what is it’s function?
Serous pericardium
- heart grows into the serous sac and fills the pericardial cavity
- potential space is left between the parietal and visceral layers
What arteries supply the thoracic wall?
- Posterior and anterior intercostal arteries
What is the path of the posterior intercostal arteries?
- posterior intercostal arteries branch from the descending aorta (apart from 12, 2 branch from Costocervical trunk of subclavian arteries)
- run in the intercostal space
- anastomose with anterior intercostal arteries
What is the path of the anterior intercostal arteries?
- arise from internal thoracic artery from subclavian artery
- run in upper part of the intercostal space in costal groove
- collateral branch runs in inferior part
- anastomose with posterior intercostal arteries
What veins drain the thoracic wall?
- Anterior intercostal veins (from internal thoracic vein)
- Posterior intercostal veins (right from Azygos vein, left from hemiazygos vein)