Week 3- superior and posterior mediastinum Flashcards
The mediastinum can be divided up into?
Superior and inferior.
Inferior is then further subdivided into anterior, middle and posterior.
What line divides the superior and inferior mediastinum?
Transverse thoracic plane- between T4 and T5.
What are the boundaries of the superior mediastinum?
Bodies of T1-T4 vertebrae posteriorly
Anteriorly- manubrium of the sternum
Inferiorly- transverse thoracic plane
Superiorly- thoracic inlet and parietal pleura
What is contained within the superior mediastinum?
Order from anterior to posterior Thymus Brachiocephalic veins and SVC Arch of the aorta Trachea Oesophagus Phrenic and vagus nerves Lymphatics
Which two veins draining the head and neck anastomose to form the superior vena cava?
Right and left brachiocephalic veins (also the inferior thyroid vein- but its tiny).
What are the branches of the arch of the aorta?
Right brachiocephalic trunk- splits into right subclavian and right common carotid.
Left common carotid
Left subclavian
Describe the course of the right vagus nerve?
Runs anterior to the right subclavian artery.
Right recurrent laryngeal loops under right subclavian artery.
Describe the course of the left vagus nerve?
Runs between left common carotid and left subclavian artery
Loops around the arch of aorta to form recurrent laryngeal nerve.
Where would you find the cardiac plexus? Which nerve forms this?
Underneath the arch of the aorta
The vagus nerve forms this
Which other plexi does the vagus nerve form?
It forms plexuses on the right and left bronchus forming the pulmonary plexus’s.
Also forms the oesophageal plexus.
How does the vagus nerve enter the abdominal cavity?
It continues into the abdomen as the anterior and posterior vagal trunks (one sits anterior to the oesophagus, one sits posterior).
Which vagal trunk is mainly formed by the left vagus nerve?
Anterior vagal trunk is mainly formed by the left vagus nerve.
Which vagal trunk is mainly formed by the right vagus nerve?
The posterior vagal trunk is mainly formed by the right vagus nerve.
Which spinal nerve roots form the phrenic nerve?
Anterior rami of C3, 4 and 5.
Which nerve supplies the diaphragm
Phrenic nerve
Describe the course of the right phrenic nerve?
Runs alongside the right brachiocephalic vein, superior vena cava and then onto the pericardium. It runs anterior to the root of the right lung and pierces the diaphragm near the caval opening.
Describe the course of the left phrenic nerve?
Lies between the left subclavian artery and vein. It runs to the left of the arch of the aorta anterior to the vagus nerve.
It runs anterior to the root of the left lung and runs along the pericardium over the left atrium and ventricle.
Pierces the diaphragm to the left of the pericardium.
Where does the trachea begin?
At C5/6 (below the larynx).
What level is the carina at? What is the significance of the carina?
Carina at T4/T5. Where the trachea divides into the left and right main bronchi.
Which muscle is found posteriorly to the trachea to allow expansion of the oesophagus?
Trachealis muscle.
At what level does the oesophagus begin?
C6