Middle Mediastinum Flashcards
What is the function of the mediastinum?
Fibrous and serous layers that surround the heart so it can expand and contract. It also supports and stabilises the heart.
Describe the structure of the fibrous pericardium
defines the middle mediastinum
surrounds the heart and the great vessels
What are the attachments of the fibrous pericardium?
attaches superiorly to the roots of the great vessels
attaches inferiorly to the central tendon of the diaphragm halting the desert of the diaphragm during inspiration
what are the attachments of the serous pericardium?
attaches to the internal surface of the fibrous layer and is continuous around the roots of the great vessels
What is the position of the transverse pericardial sinus?
it separates the great arteries and veins
Anterior- aorta and the pulmonary trunk
posterior- superior vena cava and left auricular appendage of the left atrium
what is the position of the oblique pericardial sinus?
potential space behind the left atrium
the posterior aspect of the heart
What clinical conditions can affect the pericardium?
- Cardiac tamponade- when increased fluid puts pressure on the heart
- pericarditis- inflammation of the pericardium
What forms the anterior/ sternocostal surface of the heart?
Right atrium, right ventricle, left ventricle and left auricular appendage
What forms the inferior/diaphragmatic surface of the heart?
left and right ventricles
What chamber forms the base of the heart?
left atrium
What forms the right border of the heart?
the right atrium
What forms the left border of the heart?
the left atrium and the left auricular appendage
What forms the apex? Where can you locate the apex?
- the left ventricle
- the 5th left intercostal space, mid clavicular line
What are the major relations on either side of the heart?
pleura and lungs (L+R) and the phrenic nerves
What are the major relations behind the heart?
oesophagus and descending aorta
which structures are associated with the R atrium of the mediastinum?
SVC, IVC and arch of the azygos
Which structures are associated with the left ventricle of the mediastinum?
L common carotid artery, L subclavian artery, aortic arch, thoracic aorta
How do both phrenic nerves enter the superior mediastinum?
between the veins and arterial plexuses, posterior to the brachiocephalic veins
What is the course taken by the right phrenic nerve?
right side of SVC, anterior to the root of the right hilum, right of the IVC to underside of Diaphragm at T8
What is the course of the left phrenic nerve?
anteriorly to the first part of SC artery posteriorly to the SC vein, crosses the aortic arch and passes lateral to the vagus nerve,
Explain why irrigation of the phrenic nerve will result in referred pain to the shoulder.
Give an example.
-Phrenic nerve C3,4,5 (keeps the diaphragm alive), also sensory from: central tendon of diaphragm and related parietal pleura and underlying peritoneum, mediastinal pleura, pericardium
-Supraclavicular C3,4
-hence structures with a sensory supply via the phrenic will refer pain to the shoulder tip
Example- gall bladder refers pain to R shoulder tip
