Vessels and nerves of the superior mediastinum Flashcards
Where does the superior mediastinum extend to?
extends upwards, terminating at the superior thoracic apeture.
Where does the inferior mediastinum extend to?
extends downwards terminating at the diaphragm. It is further divided into the anterior, middle and posterior mediastinum
Where do the great systemic blood vessels lie?
within the superior mediastinum, their main branches arise before passing through the superior thoracic apeture
What three branches come off the arch of the aorta?
brachiocephalic artery, left common carotid artery, left subclavian artery
What does the Brachiocephalic artery go on to supply?
right side of the head and neck and the upper right limb
What does the left common carotid go on to supply?
left side of the head and neck
what does the left subclavian go on to supply?
left upper limb
What are the main branches of the superior vena cava?
the left and right brachiocephalic veins
What are the branches of the brachiocephalic artery?
right common carotid and right subclavian artery
Where is do superior and inferior mediastinum divide?
sternal angle to the T4 vertebrae
what are the borders of the superior mediastinum?
Superior; Thoracic inlet Inferior: continuous with the inferior mediastinum at the level of the sternal angle Anterior: manubrium of the sternum Posterior: vertebral bodies of T1-4 Lateral: pleurae of the lungs
What are the other branches of the superior vena cava?
left superior intercostal vein, supreme intercostal vein and Azygous vein
What are the main nerves of the superior mediastinum?
Vagus, Phrenic, cardiac nerves and the sympathetic trunk
Where does the right vagus nerve run?
runs parallel to the trachea and passes posteriorly to the superior vena cava and the right primary bronchus
Where does the left vagus nerve run?
enters the superior mediastinum between the left common carotid and the left subclavian arteries. It descends anteriorly to the aortic arch, before travelling posterior to the left bronchus
What arises from the left vagus nerve as it passes under the aortic arch?
Left recurrent laryngeal nerve, it then continues its journey to the larynx in the tracheal-oesophageal groove
What is the Ligamentum arteriosum?
it is a remnant of the ductus arteriosum which shunts blood from pulmonary trunk to aorta in the foetus. It is found under the arch of the aorta
What are the nerve roots of the phrenic nerves?
C3, C4 and C5
which nerve if compressed causes hoarseness of the voice?
left recurrent laryngeal nerve, this can occur due to carcinoma of the oesophagus, mediastinal lymph node enlargement, aortic arch aneurysm or left lung tumour. This is because the left recurrent laryngeal nerve innervates the left vocal cords
What is the pericardium?
it is a tough sac which encloses the heart, it is mainly made up of fibrous tissue
what does the parietal pericardium cover?
lines the entire pericardial cavity, inner surface with a smooth lining.
what does the visceral pericardium cover?
the blood vessels and heart
What is the Thymus gland?
it is a primary lymphoid organ which primary function is to promote the development of t cells for the immune system. It is the most anterior structure of the superior mediastinum and sits against the posterior surface of the sternum.
what are the other structures of the superior mediastinum?
thymus, trachea, thoracic duct and the sternohyoid and sternothyroid muscles
What are the five surfaces of the heart?
anterior (sternocostal), posterior (base), Inferior (diaphragmatic), right pulmonary and left pulmonary
What are the four borders of the heart and what do they contain?
right border- right atrium, left border- left ventricle, inferior border- left and right ventricle, superior border- right and left atrium and the great vessels
What are the grooves on the surface of the heart called?
sulci
What are the main sulci of the heart and where do they run?
the coronary sulcus- runs transversely around the heart and contains the right coronary artery
the anterio and posterior interventricular sulci- can be found running vertically on their respective sides of the heart
which nerve is responsible for the somatic innervation of the pericardium?
phrenic nerve
On a Chest X-ray which parts of the heart should be visible?
left border (left ventricle and some of the left atrium) and the right border (right atria). Also the left auricular appendage
where the pain be referred to if there was painful stimulation of the diaphragm?
side of the neck and the shoulder tip. this is because the diaphragm is innervated by the phrenic nerve with nerve roots C3, C4 and C5 which originates in the neck..
If fluid collects in the pericardium (pericardial effusion) what will the consequences be to heart function?
the pericardium becomes rigid and cannot expand therefore the heart is subject to increased pressure therefore there is limited ventricular and chamber filling which will reduce cardiac output.
what is the transverse sinus?
formed by the way in which the pericardium folds around the great vessels, and is a passageway through the pericardial cavity
What is pericarditis?
inflammation of the pericardium
Where would you place a needle to remove fluid or blood from the pericardial cavity?
into the angle between the xiphoid process and left seventh costal cartilage, directed upwards 45 degrees towards left shoulder.
This is because the pericardial cavity is closest to the surface at the level of the xiphoid process and 6th costal cartilage.
