Middle Mediastinum & Heart Flashcards
what are the structures in the middle mediastinal compartment?
- pericardium
- heart
- phrenic nerves
- pericardiacophrenic vessels
- stems of great vessels
what is meant by the heart being an “electrico-mechanical” pump?
- electrical: it pumps autonomously
- mechanical: torsion and vavlvds control pressure between chambers
pericardium
- double-walled fibroserous sac which surrounds & covers the heart and roots of great vessels
- limits/preventes distension of the hart
serous pericardium
- parietal layer: lines inside of fibrous pericardium
- visceral layer: covers outside of heart (epicardium)
fibrous pericardium
CT layer outside of the parietal serous layer that forms bulk of pericardial sac
What are the layers of the heart?
- fibrous pericardium
- parietal layer of serous pericardium
- pericardial cavity
- visceral layer of serous pericardium
- epicardium
- myocardium
- endocardium
transverse sinus
separates arteries from viens (arteries are anterior while veins are posterior when viewing heart posteriorly)
oblique sinus
formed by reflection onto the pulmonary veins
what nerves innervate the pericardium
- phrenic nerves
- vagus (vagi) nerves
- sympathetic trunk
epicardium
visceral layer of the pericardium–external covering of heart
subepicardium
between epicardium and myocardium–contains fat and major vessels to the heart
myocardium
oblique fibers (torsion of chambers)
endocardium
inner lining layer–composed of endothelium backed by thin CT
subendocardium
outside of the endocardium (contains tissues of the conducting system)
what is ischemic heart disease?
it is when are of subendocardium (conducting system) is lost; thus loose conductive function of the heart
How can you find the apex of the heart?
where left mid-clavicular line meets 5th intercostal space
what is the main observation from the heart’s anterior surface
right ventricle
what is observed from the heart’s posterior surface
left atrium
what is observed from the heart’s diaphragmatic surface
R & L ventricles
what is observed from the heart’s right pulmonary surface
right atrium
what is observed from the heart’s left pulmonary surface
left ventricle
right atrium
- houses the SA node (receives input from vagus nerve)
- crista terminalis: non-conductive ridge, divides pectinate muscles from smooth surface of RA
- fossa ovalis: fibrous sheet that covered the foramen ovale
- coronary sinus valve
right ventricle
tricuspid valve, excess trabeculations relative to left ventricle, pulmonary semilunar valve
left ventricle
mitral (bicuspid) valve, more muscular than right ventricle, delivers blood through aortic semilunar valve for systemic flow
semilunar valves
the aortic valve has openings on its right and left leaflets for coronary arteries
what are the heart sounds
- S1 is first sound, closing of a-v valves
- systole (ventricles contract)
- S2 is second sound, closing of semilunar vavles
- diastole (ventricles relax)
conducting system of heart
- SA node: along upper end of sulcus terminalis (near SVC); pacemaker; sympathetic and parasympathetic innervation
- AV node: interatrial septum
- Bundle of His
- Bundle branches
- Purkinje fibers
function of the skeleton of the heart
- fibrous CT functions as attachment point for valves and muscles
- provides support and actsa as electrical insulator preventing conduction between atria and ventricles
coronary arteries
- right and left artery arise from the (R &L aortic sinuses of aortic semilunar valve) and supply nutrients to the heart
