12-09-22 - Heart - Internal Structure and Surface Anatomy Flashcards
Learning outcomes
• Describe the margins and surfaces of the heart
• Describe the morphological features of the cardiac valves
• Describe the surface anatomy of the heart and its valves in relation to clinical examination and the interpretation of radiographs
• Explain why points of auscultation of heart sounds are different from the surface projection of the heart valves
• Describe the functional anatomy of the chambers of the heart
• Explain the functional importance and position of the fibrous skeleton of the heart
• Explain the clinical significance of papillary muscles and chorda tendinea
• Name the structures that form the cardiac borders on chest xray and identify anatomical structures on medical images
What are the 2 types of circulation in the body?
What route do they each involve?
What pressure do they each operate at?
What % of blood in the body is in each circulation at any given time?
• Types of circulation in the body:
1) Pulmonary circulation
• Right heart pumps deoxygenated blood to the lungs
• Operates at low pressure – 12-16mmHg
• Roughly 9% of blood in the body is in pulmonary circulation
2) Systemic circulation
• Left heart pumps oxygenated blood throughout the body
• Operates at high pressure
• Roughly 84% of the blood in the body is in systemic circulation
Name the structures that make up the 6 heart surfaces.
Why is the apex of the heart at the bottom?
Where is the apex located?
What is the base located?
Structures that make up each of the heart’s surfaces:
1) Sternocostal (anterior) surface
• Right ventricle
• Right atrium (bit less)
• Left ventricle (less)
2) Diaphragmatic (inferior) surface
• Left ventricle
• Right ventricle (less)
• Separated from the base of the heart by the coronary sinus/sulcus
3) Right pulmonary surface
• Right atrium
4) Left pulmonary
• Left ventricle (cardiac impression in the left lung)
5) Apex
• Formed by left ventricle
• Left 5th intercostal space
• 8-10cm left of the midlines
• More superior and lateral in children
• Because of rotation during foetal development, the apex of the heart (top of the cone) is at its bottom and left of the midline
6) Base
• Composed primarily of the left atrium and pulmonary veins
• Small portion of right atrium
• Fixed posteriorly to the pericardium at the level of T6-T9 (T5-T8 when lying down)
What are the margins of the heart?
What are margins used for?
What are auricles of the heart?
Where do they attach?
• Margins of the heart:
1) Right margin – right atrium
2) Left margin – left ventricle and left auricle
3) Inferior margin – right ventricle and left ventricle (less)
4) Superior margin – left and right atria and left and right auricles
• Margins are used for radiological evaluation, where we can see which margins are blurred (e.g can indicate something like a pulmonary oedema)
• Margins do not equal surfaces
• Auricle refers to an ear-shaped pouch in the atrium of the heart
• Each auricle is attached to the anterior surface of each atrium, therefore there is a left and a right auricle
What are external sulci?
What is their function?
What do external sulci correspond to?
What are the 3 external sulci?
What blood vessels run through them?
• External sulci are external surfaces embedded in fat
• External sulci function as channels for vascular bundles
• External sulci or grooves correspond to the internal partitions that divide the heart into chambers
• External sulci with vessels that run through them:
1) Anterior interventricular sulcus
• Anterior interventricular artery
• Great cardiac vein (anterior interventricular vein)
• Right of the apex of the heart
2) Coronary sulcus
• Separates atria from ventricles
• Right coronary artery
• Left circumflex artery
• Coronary sinus
3) Posterior interventricular sulcus
• Posterior interventricular artery
What is the role of septa in the heart?
What are the 3 septa in the heart?
• Septa in the heart separate the heart into 4 chambers
• Septa in the heart:
1) Interatrial (IA) septum
2) Interventricular (IV) septum
3) Atrioventricular (AV) septum
What is the right atrium?
What 4 places does the right atrium receive blood from?
Do these supplies have valves?
What is the crista terminalis?
What is it externally?
What is the surface of the right atrium like?
• The right atrium is a temporary reservoir for deoxygenated blood
• The right atrium receives blood from:
1) Opening of Superior Vena Cava (SVC)
• Deep to the joint between right 3rd CC and sternum
• No valve
2) Opening of Inferior Vena Cava (IVC)
• No valve
• Valve of inferior vena cava - guides blood to the foramen ovale in foetus
3) Opening of Coronary Sinus (venous drainage of most of the heart)
• Valve of coronary sinus
• Prevents regurgitation (opposite direction from normal) of blood
4) Opening of Small cardiac veins (venous drainage of the heart)
• Internally, the crista terminalis is a muscular ridge that separates the right atrium from the right auricle
• This exists as the sulcus terminalis externally
• The right atrium has a smooth surface
Where is the fossa ovalis located?
What is located at the fossa ovalis?
What is the margin of the fossa ovalis?
• The fossa ovalis is located on the right side of the Interatrial (IA) septum
• The fossa ovalis is the location of the foramen ovale, which is a hole between the right and left atria of the heart that exists before birth and allows blood to bypass the lungs
• The margin of the fossa ovalis is the limbus fossae
What is the right auricle?
What is the function of the right auricle?
• The right auricle is a rough surface formed by the pectinate muscles
• Auricle refers to an ear-shaped pouch in the atrium of the heart
• The right auricle provides some power of contraction without significantly thickening the cardiac wall
What goes into the right ventricle?
What does the right ventricle sit on?
What separates the right and left ventricle?
What is the shape of the right ventricle?
How thick is the right ventricle wall?
What do the walls of the right ventricle have?
What is the outflow tract of the right ventricle?
How does blood exit the right ventricle?
• Deoxygenated blood from the right atrium enters through the right atrioventricular orifice (oval aperture that serves as the communication between the right atrium and right ventricle)
• The right ventricle sits on the central tendon of the diaphragm
• The right and left ventricle are separated by the interventricular (IV) septum, which is concave in shape and bulges into the right ventricle
• The right ventricle is triangular
• The right ventricle wall is 3-4mm in thickness
• The walls of the right ventricle have numerous muscular ridges called trabeculae carnea (meaty ridges)
• The outflow tract of the right ventricle is the infundibulum (conus arteriosus) which has a smooth surface and is where the pulmonary trunk arises
• The blood flows upwards, backwards, and to the left out of the right ventricle and the heart
What are the 3 types of muscle on the right ventricle wall?
Where do chorda tendinea attach?
What is the role of the chorda tendinea?
• There are 3 types of muscles on the right ventricle wall:
1) Trabecula carnea (meaty ridges)
2) Septomarginal trabecula
• Bridge between the IV septum and anterior papillary muscles (holds onto valve cusps)
• Only in the right ventricle
• Carries right bundle branch of AV bundle of cardiac conduction system
3) Papillary muscles
• 3 muscles usually
• Named relative to their position
• Fibrous chords called chorda tendinea (heart strings) run between their apex and free edges of the tricuspid valves
• Papillary muscles contract before ventricular contraction
• The chorda tendinea from one papillary muscle attach to more than one cusp
• The chorda tendinea prevent eversion of cusps, which prevent the regurgitation of blood into the atria during ventricular systole
What does the tricuspid valve close?
What does it consist of?
Where does each cusp of the valve attach?
How does blood flow through the tricuspid valve?
Where is the pulmonary valve found?
What does the pulmonary valve consist of?
What can be found at the free end of each semi-lunar cusp?
What does each cusp form?
• The tricuspid valve closes the right AV orifice
• The tricuspid valve consists of 3 semi-lunar cusps (anterior, posterior, and septal)
• The base of each cusp of the tricuspid valve attaches to the right fibrous ring (anulus fibrosus – part of the cardiac skeleton)
• Blood flows forwards and medially through the tricuspid valve
• The pulmonary valve is found between the right ventricle and the pulmonary trunk
• The pulmonary valve consists of 3 semi-lunar cusps (anterior, right, and left)
• On their free edge, there is the nodules of the semilunar cusps, which are tendinous fibres that strengthen the cusp
• Each cusp forms a pulmonary sinus, which helps closure of the valve after systole
What does the left atrium form?
How many pulmonary veins are there?
Do pulmonary veins have valves?
What does the left atrium consist of?
Where is the left auricle located?
Why is there a depression on the IA septum?
• The left atrium forms most of the base of the heart
• Foul pulmonary veins carry oxygenated from the lungs to the left atrium
• Pulmonary veins do not have valves
• The left atrium consists of the left atrium and the left auricle
• The left auricle is a flap of heart wall located on the anterior surface of the left atrium of the heat
• A depression is left on the IA septum (falx septi) caused by the fusion of the valve of foramen ovale after birth (not on the same level as foramen ovale)
What flows into the left ventricle (LV)?
What direction does it flow?
Where is the apex found?
What is the thickness of the thickest wall in the left ventricle?
What is the LV pressure?
What 2 muscles can be found on the left ventricular wall?
• Blood from the left atrium enters through the left atrioventricular opening through the mitral valve into the left ventricle
• Blood flow anteriorly into the left ventricle and towards the apex.
• The apex is found in the left ventricle
• The thickest wall in the left ventricle is 8-12mm thick
• The pressure of the LV is 70-120mmHg
• Muscles on left ventricular wall:
1) Trabecula carnea (muscular ridges)
2) Anterior and posterior papillary muscles
Where is the mitral (bicuspid) valve located?
What does the mitral valve consist of?
Where are the cusps of the valve attached?
Where do the chorda tendinea extend on this valve?
What is the outflow tract of the left ventricle?
What does this tract need to be?
What does the aortic valve close over?
What does the aortic valve consist of?
Where are these structures located?
What structures is between the cusps and aortic wall?
What function do these structures have?
• The left AV orifice is closed by the mitral (bicuspid) valve
• The mitral valve consists of 2 semi-circular cusps: anterior and posterior
• The bases of cusps are attached to the left fibrosus ring (anulus fibrosus -part of the cardiac skeleton)
• The chorda tendinea of the mitral valve extend between the free margins of the papillary muscles to the cusps of the mitral valve
• The outflow tract of the left ventricle is the aortic vestibule (portion of the ventricle immediately below the aorta)
• The aortic vestibule needs to be smooth to encourage laminar flow (smooth flow through organisation of blood cells)
• Blood in the left ventricle is ejected into the aorta
• The aortic orifice (connection between left atrium and left ventricle) is closed over by the aortic valve
• The aortic valve consists of 3 semi-lunar cusps (right, left, and posterior) at the apex of the aortic vestibule
• Between the superior surface of the cusps and aortic wall are pocket like aortic sinuses (sinus valsalvae)
• Right and left cusps have coronary sinuses, which lead to coronary arteries that supply the heart,
• The posterior cusp has no coronary sinus
• These coronary sinuses allow for the coronary arteries to be filled when the heart is relaxed (during diastole)
Heart on an ultrasound diagram
What is the fibrous skeleton of the heart?
What is it made by?
What is it formed by?
What exists between these structures?
Where is AV bundle of His found?
What is the role of the AV bundle of His here?
How does it do this?
What are 6 functions of the fibrous skeleton of the heart?
• The fibrous skeleton of the heart is a structural support frame
• It is formed by a complex set of fibrous rings with connecting areas
• The fibrous skeleton is formed by 4 fibrous rings (anulus fibrosus) around AV, aortic and pulmonary valves
• Between these 4 fibrous rings, there are 2 trigones (left and right) and the membranous portions of the IA, IV, and AV septa
• The AV bundle of His is found in the right trigone between the fibrous rings of the AV valves and the aortic valve
• The AV bundle of His serves as the only electrical connection between the atria and the ventricles
• It achieves this by being the only conductive route through the fibrous skeleton of the heart
• Functions of the fibrous skeleton of the heart:
1) Provides points of attachment for the cusps
2) Maintains the patency and integrity of AV septum and semi-lunar orifices
3) Serves as origin/insertion for atrial and ventricular muscles
4) Insulates the atria from ventricles
5) Allows independent atrial and ventricular contraction
6) Atrioventricular bundle of His should be the only conduction between them (prevents arrythmias)
What are the 3 layers of the cardiac wall from inside to outside?
• Layers of the cardiac wall from inside to outside:
1) Endocardium
• Thin layer of endothelium that lines the inner surface of the walls as well as the valves
• Receives oxygen and nutrients directly from the chambers of the heart
2) Myocardium
• Atrial musculature
• Ventricular musculature
• Muscles are arranged in spiral and circular bundles
• Originates and inserts on fibrous skeleton
3) Epicardium
• Matches up with the visceral layer of the serous pericardium
Where are the 4 corners of the heart located?
Which corner is the apex of the heart?
• Locations of the 4 corners of the heart:
1) 1st corner
• Right 3rd costal cartilage
• 2cm right of the midline
2) 2nd corner
• Right 6th costal cartilage
• 2cm right of the midline
3) 3rd corner (apex of heart)
• Left 5th costal cartilage
• 7-9cm left of the midline
4) 4th corner
• Left 2nd costal cartilage
• 3cm left of the midline
What are the surface projections of each of the 4 valves?
Describe the direction of blood flow through each valve.
Why is it important to the direction blood flows out of valves?
• Surface projection of each of the 4 valves:
1) Tricuspid valves
• Behind right half of the sternum at the level of 4th intercostal space
• Blood flows anteriorly and medially i.e towards the left
• 5 o’clock position
2) Mitral valve
• Posterior to the articulation between left 4th CC and the sternum
• Blood flows anteriorly and inferiorly towards the apex
• 5 o’clock position
3) Pulmonary Valve
• Posterior to the articulation between 3rd left CC and the sternum
• Blood flow Superiorly and towards the left
• 1 o’clock
4) Aortic valve
• Posterior to the sternum at the level of the 3rd intercostal space
• Blood flow superiorly and to the right
• 11 o’clock
• It is important to know the direction of blood flow out of the valves so we can hear different areas of the heart during clinical examination
What causes Cardiac Auscultation (heart sounds)?
What causes heart sounds 1 to 3?
What 5 factors can cause changes in heart sounds?
• Valves open and close due to changes in blood pressure, and when they close, they make sounds which are known as cardiac auscultation
• 1ST heart sound is caused by closure of the AV valves (mitral and tricuspid)
• 2nd heart sound is caused by the closure of semi-lunar valves (aortic and pulmonary)
• 3rd heart sound is caused by the rapid filling of the ventricles
• Changes in heart sounds can be caused by:
1) Sitting or recumbent
2) Inspiration
3) Expiration
4) Valsalva manoeuvre – breathing method that can slow heart rate when it is beating too fast
5) Exercise
Where can the function of each heart valve be heart best on the body?
• Where can the function of each heart valve be heart best on the body:
1) Tricuspid valve (HS1)
• Best heard just to the left of the lower part of the sternum near the 5th intercostal space
2) Mitral valve (HS1)
• Best heard over the apex of the heart in the left 5th intercostal space at the midclavicular line (apex cordis)
3) Aortic valve (HS2)
• Best heard over the medial end of the right 2nd intercostal space
4) Pulmonary valve (HS2)
• Best heard over the medial end of the left 2nd intercostal space
Label these margins and great vessels of the heart on this x-ray
Label this structure of the thoracic cavity
Label these structures of the thoracic cavity x-ray
