Thorax 3 - The Heart (gross anatomy) Flashcards
what part of the mediastinum is the heart located?
middle mediastinum
what axis does the heart lie on? why is this clinically important?
oblique axis/ orientation - important for proper ECG interpretation
what are the 5 main surfaces of the heart?
anterior/sternocostal
posterior/base
inferior/ diaphragmatic
right pulmonary
left pulmonary
which chamber mainly forms the anterior (sternocostal) surface of the heart?
right ventricle
which chamber mainly forms the posterior (base) surface of the heart?
left atrium
which chamber mainly forms the inferior (diaphragmatic) surface of the heart?
left ventricle (small part of right ventricle)
which chamber mainly forms the right pulmonary surface of the heart?
right atrium
which chamber mainly forms the left pulmonary surface of the heart?
left ventricle
which of these structures doesn’t contribute to the anterior/sternocostal surfaces of the heart?
a) right atrium
b) right ventricle
c) left atrium
d) left ventricle
C: left atrium - contributes to posterior/base surface
beyond the left atrium, what other chamber gives a small contribution to the posterior surfaces of the heart?
right atrium
what are the 4 main borders of the heart?
right border
left border
inferior border
superior border
what chambers contribute to the superior border?
right atrium
roots of great vessels (aorta & pulmonary trunk)
left atrium
what chambers contribute to the inferior border?
right ventricle
left ventricle
what chambers contribute to the right border?
right atrium
what chambers contribute to the left border?
left atrium
left ventricle
the left & right ventricles contribute to WHAT border of the heart?
inferior
what vessel does the atrioventricular (coronary) sulcus contain?
right & left coronary arteries
what vessels (one vein, one artery) does the anterior interventricular sulcus contain?
anterior interventricular artery/ left anterior descending artery (LAD)
great cardiac vein
what vessels (one vein, one artery) does the posterior interventricular sulcus contain?
posterior interventricular artery
middle cardiac vein
what structure separates the two atria?
interatrial septum
what structure separates the two ventricles?
interventricular septum
what does the right pump of the heart do?
receives deoxygenated blood from the body > right atrium > right ventricle > pulmonary artery > lungs for oxygenation
what does the left pump of the heart do?
receives oxygenated blood from the lungs via pulmonary veins > left atrium > left ventricle > aorta > systemic circulation
what is the clinical significance of the cardiac silhouette on a chest X-ray?
helps assess heart size & shape - aids in diagnosis of different cardiac and/or pulmonary conditions
which surfaces & borders does the right atrium contribute to?
surfaces - right pulmonary surface (some of anterior & base surfaces)
border - right border
the right atrium has a smooth & rough part - is the smooth part anterior OR posterior?
smooth posterior
rough anterior (pectinate muscles)
what is the difference between the smooth posterior & rough anterior parts of the right atrium’s internal anatomy?
smooth POSTERIOR part contains the openings of the SVC, IVC & coronary sinus (receives deoxygenated blood) - allows for laminar flow of blood into right atrium
rough ANTERIOR part contains pectinate muscles
what is the crista terminalis? what does it separate?
C-shaped muscular ridge - separates smooth posterior wall from the rough anterior wall
what feature on the external surface of the heart corresponds to the presence of the crista terminalis?
sulcus terminalis (a shallow groove)
what are the pectinate muscles? why are there more present in the RIGHT atrium?
ridged muscular structures present in the atria - help increase the contractile strength of the atrial walls
more present in the right atrium as venous system blood has a lower pressure - more muscle needed for stronger atrial contractions
what are the major openings into the right atrium? (4)
SVC
IVC
coronary sinus
right atrioventricular orifice
what valve guards the right atrioventricular orifice?
tricuspid valve (3 cusps) - blood from RA > RV
what internal feature of the right atrium has the fossa ovale?
interatrial septum (separates RA & LA)
what is the significance of the fossa ovale?
remnant of the embryological foramen ovale - used to shunt oxygenated blood from RA to LA as foetal lungs aren’t developed
closes once foetus is born
what can failure of closure of the foramen ovale lead to?
leads to a patent foramen ovale - mixing of oxygenated & deoxygenated blood
which surfaces & borders of the heart does the right ventricle contribute to?
surface - majority of anterior/sternocostal surface (& part of diaphragmatic/inferior surface)
border - most of inferior border
what are the three main muscular projections inside the right ventricle?
trabeculae carnae
papillary muscles
moderator band/ septomarginal trabeculae
what are the trabeculae carnae?
irregular muscular ridges - provide structural support and aid contraction (during systole)
what is the function of the papillary muscles in the right ventricle?
papillary muscles contract to tighten the chordae tendinea - prevent tricuspid valve prolapse & backflow of blood
describe the base & apex attachments of the papillary muscles
base of muscles projects from ventricular wall
apex of muscles attached to chordae tendinea (tendinous cords)
what is the role of the moderator band?
extends from the interventricular septum to anterior papillary muscle - contains the right bundle branch of the cardiac conduction system
moderates conduction in the right ventricle
what are the two main openings in the right ventricle? (2)
right atrioventricular orifice
pulmonary veins (4) - 2 on left, 2 on right
what valve guards the pulmonary trunk? how many cusps?
pulmonary valve - 3 cusps (no chordae tendinae)
which valves have chordae tendinea attachments?
tricuspid & mitral valves
which valve only has 2 cusps?
mitral/ bicuspid valve (between LA > LV)
what is the conus arteriosus (infundibulum)?
feature of the right ventricle - smooth uppermost part of RV that leads blood to the pulmonary trunk, ensures smooth blood flow
what condition can damage to the papillary muscles in the right ventricle cause?
tricuspid valve regurgitation - valves prolapse, causes the backflow of blood into RA from RV
what surface of the heart does the left atrium contribute to?
base/ posterior surface
what part of the left atrium contains the pectinate muscles?
left auricle - small, anterior projection of the left atrium
in what structure of the heart is the fossa ovalis present?
in the interatrial septum (marks the foetal remnant of the foramen ovale that shunted oxygenated blood from RA > LA)
how many pulmonary veins open into the left atrium? what is their function?
4 (superior & inferior PVs from left and right sides) - carry oxygenated blood from the lungs
what are the openings present in the left atrium?
left atrioventricular orifice (guarded by the mitral valve)
pulmonary openings (4 - from pulmonary veins)
what valve guards the left atrioventricular orifice?
bicuspid/ mitral valve - allows blood to flow from LA > LV during diastole
how does the left ventricle differ from the right ventricle in wall thickness? why?
wall is 2-3 times thicker = needs higher pressure needed to pump blood into systemic circulation
which surface/part of the heart does the left ventricle form exclusively?
the apex of the heart
what muscular projections are present in the left ventricle?
trabecular carnae - more numerous and finer than in RV
papillary muscles - attached to chordae tendineae which anchor the mitral valve
does the left ventricle have the moderator band?
NO - the right ventricle does (has the RIGHT bundle branch of the cardiac conduction system)
does the left ventricle have the crista terminalis?
NO - present in right ventricle
what are the main openings of the left ventricle? what guards them?
left atrioventricular orifice - guarded by the mitral valve
aortic orifice - guarded by aortic valve
what is the aortic vestibule?
smooth non-muscular portion of the left ventricle below the aortic orifice - ensures smooth blood flow from LV > aorta
describe the position of the auscultation point for the aortic valve
medial end of the 2nd intercostal space of the right side of the sternum
describe the position of the auscultation point for the pulmonary valve
medial end of the 2nd intercostal space of the LEFT side of the sternum
which valve can be auscultated at the 5th left intercostal space along the midclavicular line?
mitral valve
describe the position of the auscultation point for the tricuspid valve
4th-5th left intercostal space at the lower sternal border
which valve can be auscultated on the right side of the sternum?
aortic valve
why do auscultation points differ from the actual anatomical location of the heart valves?
auscultation points are chosen based on the direction of blood flow and how sound propagates through the chest wall rather than their exact anatomical location
the best place to hear the closing sounds of heart valves is where the blood flows immediately after passing through them instead of directly over the valves
how do the right and left ventricles differ structurally? (5)
- LV wall is 2-3 times thicker than the right
- no moderator band or cristae terminalis present in LV
- trabeculae carnae are finer & more in number in LV compared to RV
- LV forms the apex of the heart, RV forms majority of the anterior surface
- RV has the conus arteriosus/infundibulum leading to the pulmonary trunk; LV has the aortic vestibule leading to the aorta
what are congenital abnormalities of the interatrial septum known as? which is the most common of these?
atrial septal defects
patent foramen ovale is the most common - (failure of the foramen ovale to close following birth)
what sort of blood shunting occurs with atrial septal defects?
left-to-right shunting (oxygenated blood from LA > RA)
what occurs to the right sided chambers of the heart & pulmonary trunk as a result of atrial septal defects?
right atrium & ventricle enlarge
dilation of pulmonary trunk
what consequence would a patent foramen ovale have on the right-sided chambers of the heart?
RA & RV enlarge and pulmonary trunk dilation
- because of left-to-right shunt of oxygenated blood from LA > RA
what direction of blood shunting occurs in ventricular septal defects?
left-to-right shunting (oxygenated blood from LV > RV)
what is the clinical consequence of the large shunting of blood that occurs with ventricular septal defects?
increases pulmonary flow - causes severe pulmonary disease (e.g. pulmonary hypertension)
can lead to heart failure
how can ventricular septal defects lead to heart failure?
ventricular septal defects lead to a left-to-right shunt of oxygenated blood from LV > RV
increases pulmonary blood flow, leads to pulmonary hypertension, can then lead to heart failure
list the structures contained within the right atrium (openings & gross anatomy)
smooth posterior part & rough anterior part with pectinate muscles
cristae terminalis (separates smooth & rough parts)
fossa ovale - present in interatrial septum
openings for: SVC, IVC, coronary sinus, right atrioventricular orifice (guarded by tricuspid valve)
list the structures in the right ventricle (openings & gross anatomy)
3 muscular projections - trabecular carnae, papillary muscles (with chordae tendineae attachments), moderator band/ septomarginal trabeculae
conus arteriosus (smooth non-muscular part between RV and pulmonary trunk)
openings for: right atrioventricular orifice, pulmonary openings (from RV > pulmonary trunk)
which heart chamber has the septomarginal trabeculae?
right ventricle
which heart chamber has the conus arteriosus/ infundibulum?
right ventricle
list the structures present in the left atrium
left auricle - only rough part of LA with pectinate muscles
interatrial septum - fossa ovale & valve of fossa ovale
openings for: pulmonary veins (4) & left atrioventricular orifice (guarded by mitral/ bicuspid valve)
list the structures present in the left ventricle
trabecular carnae
papillary muscles - chordae tendineae attachments with mitral valve
(NO cristae terminalis & moderator band)
aortic vestibule - smooth non-muscular part below aortic orifice
openings for: left atrioventricular orifice, aortic orifice
