middle mediastinum Flashcards
What are the boundaries of the middle mediastinum
Anterior – anterior pericardium
Posterior – posterior mediastinum
Lateral – mediastinal pleura
Inferior – diaphragm
Superior - transverse thoracic plane (T4/5)
It’s the broadest part of the interpleural space
what are the contents of the middle mediastinum
Heart and pericardium Ascending aorta Pulmonary trunk and arteries Pulmonary veins Nerves
what are the external features of the heart
Right and Left auricles (for extra blood to enter atrium) atrioventricular groove (below right atrium) inter ventricular groove
what great vessels are in the middle mediastinum
ascending aorta
pulmonary trunk
pulmonary veins
vena cava
how does blood leave the heart via the ascending aorta
via ascending aorta, aortic arch, descending thoracic aorta (posterior mediastinum) and descending abdominal aorta
how does blood leave the heart via the pulmonary trunk
pulmonary trunk, branches into l and r pulmonary arteries and enter hilum/ root of lungs
what makes up the right atrium
2 regions – sinus verarum (smooth walled) and pectinate muscle
SVC, IVC and coronary sinus feed into it
fossa ovalis
crista terminalis (division between two muscle types)
what makes up the right atrium
fossa ovalis
auricle
openings of pulmonary veins
what is seen in both ventricles
chord tendineae
papillary muscle
trabecular carneae (uneven to stop blood adhering to walls and aid contraction)
moderator band
outflow smooth walled for smooth blood flow
what are the valves of the heart
Semilunar (pulmonary and aortic)
Atrioventricular (tricuspid and bicuspid)
what makes up the bicuspid valve
an anterior and posterior cusp
what makes up the tricuspid valve
an anterior, posterior and septal cusp
what are cusps
leaflets attaching to chordae tendineae to attach to papillary muscles
what cusps do semi lunar valves have
Pulmonary valve cusp Left Right anterior Aortic valve cusp Left Right Posterior
what aortic cusps feed into which arteries (blood pockets)
Right coronary artery from right cusp and left to left
what is the pericardium
3 layered sac which heart is suspended in
Attached to great vessels superiorly and diaphragm inferiorly
Influenced by movement of the great vessels, sternum and diaphragm
Phrenic nerve travels over pericardium
what are the functions of the pericardium
Protect heart from overfilling (cardiac distension)
Retains heart in positions (pericardio-sternal ligaments)
what are the layers of the pericardium
Serous (internal) with parietal and visceral (or epicardium) layers
Fibrous (external)
Pericardial cavity located between parietal and visceral pericardium, contains a small amount of serous fluid to allow for uninhibited movement
what are pericardial sinuses
Where parietal and visceral layers of serous pericardium meet, the reflections form 2 sinuses
what is the transverse sinus
located between outflow vessels of the heart and inflow vessels – can be used in surgery to clamp the outflow of blood from the heart
what is the oblique sinus
located between pulmonary veins
A sinus is a sac/cavity in an organ or tissue
where are the coronary arteries located
Coronary vessels located in the atrioventricular and interventricular grooves
Two main coronary arteries are right and left (from ascending aorta)
what anastomoses are found in the coronary arteries
Functional (potential) anastomoses exist between the coronary artery branches
Eg end branches of anterior interventricular artery and posterior interventricular artery
These do not maintain substantial collateral circulation if major branches suddenly occluded
what is coronary artery dominance
Dominance is defined by the coronary artery which gives rise to the posterior IV artery
67% right dominant and 15% left (where posterior IV artery branches from the circumflex artery)
