Anatomy of The Mediastinum Flashcards
1. Identify the divisions of the mediastinum 2. Describe the organisation of the structures in the superior mediastinum 3. Describe the arrangement of the pericardium 4. Describe the contents of the posterior mediastinum 5. Explain the arterial supply and the venous drainage of the thoracic wall 6. Distinguish between the pulmonary and the systemic blood supply to the lungs
Where does the mediastinum start
- Thoracic inlet/aperture
- T1
Where does the mediastinum end
- Diaphragm - end point (inferior boundary)
- the diaphragm can move a bit as it moves up and down
Where is the front and back of the mediastinum
- Thoracic vertebrae - this is the back
- Sternum and costal cartilages - this is the front
the mediastinum is…
Highly mobile because it contains hollow air or fluid filled structures
why does the mediastinum need to be highly mobile
- allows for movement of lungs, heart, great vessels and oesophagus
What divides the heart into superior and inferior
Transthoracic plane
What does the transthoracic plane do
divide the heart into superior and inferior
where is the transthoracic plane
- sternal angle T4/T5
- this is where rib 2 inserts
Define the transthoracic plane
- Transthoracic plane is defined in terms bony body wall structures which are independent of gravity
when you are describing the position of structures what way is the person postioned
Supine
describe where the - arch of the aorta - bifurcation of the trachea - central tendon are in a person in the supine position
- Arch of aorta lies superior to transthoracic plane
- Bifurcation of trachea transected by transthoracic plane
- Central tendon lies at level of xiphisternal junction and T9
describe where the - arch of the aorta - bifurcation of the trachea - central tendon are in a person in a standing position
- Arch of aorta transected by transverse thoracic plane
- Tracheal bifurcation lies inferior to transthoracic plane
- Central tendon falls to middle of xiphoid process T9-10 IV disc
what are the structures in the superior mediastinum
- Brachiocephalic veins and superior Vena Cava
- Great vessels – ascending and arch of aorta
- Trachea
- Oesophagus
- Thymus Gland – overlies the great vessels, in adults it is not as prominent
- Phrenic nerve
- Thoracic duct and lymphatic trunks
What are the structures in the inferior mediastinum
- Heart
- Oesophagus
- Descending aorta
- Inferior Vena Cava
List the structures in the superior mediastinum as if going from anterior to posterior
- Thymus
- Veins
- Brachiocephalic and SVC
- Phrenic nerve
- C3,4,5 – innervation to diaphragm
- Arteries
- Arch of aorta and great vessels
- Vagus nerve and recurrent laryngeal nerves (this is a branch of the veagus nerve)
- Trachea
- Oesophagus
- Thoracic duct and lymphatic trunks
what nerves are in the mediastinum
Vagus
Phrenic
sympathetic trunk
What does the vagus nerve innervate in the mediastinum
- Oesophagus
- Heart
- Bronchi
What does the recurrent Laryngeal loop do
it innervates the larynx
part of the vagus nerve
describe the difference between the left and the right recurrent laryngeal
- On the right side it loops underneath the right subclavian arteries and goes back towards the neck (higher up)
- On the left side it gets stuck underneath and aorta arch before it loops back to the larynx (lower down)
what does the Phrenic nerve innervate
Diaphragm
- sensory to the pericardium mediastinal pleura
what are the spinal levels of the Phrenic Nerve
C3 C4 C5
what are the two phrenic nerves
Left and Right