Heart: Internal Structure and Surface Anatomy Flashcards
What pressures do each side of the heart pump blood into their respective circulations?
Pulmonary - 12 – 16 mmHg
Systemic - 70 – 120 mmHg
Name all the surfaces of the heart
Anterior (sternocostal) Left Pulmonary Right Pulmonary Base Diaphragmatic (inferior) surface
What structures make up the sternocostal (anterior) surface of the heart?
✓ Right ventricle
✓ Right atrium
✓ Left ventricle
What structures make up the diaphragmatic (inferior) surface of the heart?
✓ Left ventricle ✓ Right ventricle
✓ Separated from the base of heart by coronary sinus
What structures make up the right pulmonary surface of the heart?
✓ Right atrium
What structures make up the left pulmonary surface of the heart?
✓ Left ventricle (cardiac impression in the left lung)
Describe the location of the apex of the heart
✓ Left 5th intercostal space and 8-10 cm left of midline
✓ More superior and lateral in children
What structures make up the base of the heart?
✓ Composed primarily of left atrium and pulmonary veins, small portion of right atrium.
✓ Fixed posteriorly to the pericardium, at the level of T6(5)-T9(8) vertebrae
Name the margins of the heart
Obtuse - superior to apex
Inferior (acute) - medial to apex
Right margin - right atrium
Left margin - left ventricle and left auricle
Inferior margin - Right ventricle + left ventricle
What are the external suci?
✓ Coronary sulcus − Separates atria from ventricles − Right coronary artery − Left circumflex artery − Coronary sinus
✓ Anterior interventricular sulcus
– Anterior interventricular artery
– Great cardiac vein [Anterior interventricular vein]
– Right of the apex
✓ Posterior interventricular sulcus
– Posterior interventricular artery
– Middle cardiac vein [Posterior interventricular vein]
Name all the septa of the heart bitch
✓ Interatrial (IA) septum
✓ Interventricular (IV) septum
✓ Atrioventricular (AV) septum
Name all the septa AND chambers of the heart
✓ Interatrial (IA) septum ✓ Interventricular (IV) septum ✓ Atrioventricular (AV) septum ✓ Right (RA) and left (LA) atria ✓ Right (RV) and left (LV) ventricles
What separates the right atrium form the right auricle?
✓ Internally, crista terminalis is a muscular ridge that separates right atrium from right auricle
✓ Sulcus terminalis externally
Describe the fossa ovalis
✓ Fossa ovalis − On the right side of IA septum − Site of foramen ovale in foetus − Margin is limbus fossae ovali The fossa ovalis is the remnant of a thin fibrous sheet that covered the foramen ovale between the right and left atrium during fetal development
Describe the various openings into the right atrium
✓ Opening of SVC − Deep to the joint between right 3rd costal cartilage and sternum − No valve − Intervenous tubercle ✓ Opening of IVC − Valve of inferior vena cava ✓ Opening of coronary sinus − Valve of coronary sinus prevent regurgitation of blood ✓ Openings of smallest cardiac veins
Describe the right auricle
Rough surface, formed by pectinate muscles
− Provide some power of contraction without significantly thickening the cardiac wall
Describe the structure of the right ventricle
✓ Walls of RV have numerous irregular muscular ridges called Trabeculae carnea
✓ Sits on central tendon of diaphragm
✓ Wall thickness 3-4 mm.
✓Morphologically there are 3 types of muscles on right ventricle wall
1. Trabeculacarnea
2. Septomarginal trabecula
3. Papillary muscles
What is the outflow tract of the right ventricle?
Outflow tract is Infundibulum [conus arteriosus] where the pulmonary trunk arises
− Blood flows upwards, backwards and to the left
− Surface of Infundibulum is smooth.
Discuss the septomarginal trabecula and papillary muscles found in the right ventricle
Septomarginaltrabecula
− Bridge between IV septum and anterior papillary muscle
− Only in RV
− Carries right bundle branch of AV bundle of cardiac conduction system
Papillary muscles
− Three muscles (usually!)
− Named relative to their position
− Fibrous chords called Chorda tendinea run between their apex and free edges of tricuspid valve cusps
− Contract before ventricular contraction
Discuss the chorda tendinea of the right ventricle
✓Chorda tendinea prevent evertion of cusps→regurgitation of blood into the atria during ventricular systole
✓Chorda tendinea from one papillary muscle attach to more than one cusp
Discuss the tricuspid valve
✓ Closes right AV orifice
✓ Consists of 3 cusps (anterior,
posterior and septal)
✓ Base of each cusp attached to right fibrous ring (anulus fibrosus)
✓ Blood flows forwards and medially through this valve
Discuss the pulmonary valve
✓ Consists of 3 semilunar cusps: anterior, right and left
✓ On their free edge, there is nodule of the semilunar cusp
✓ Each cusp forms a pulmonary sinus, which helps closure of pulmonary valves after systole
Discuss the left atrium
✓ Forms most of the base of heart
✓ Four pulmonary veins carry
oxygenated blood from the lungs
− Pulmonary veins do not have valves
✓ Consists of Left auricle and left atrium
✓ Depressed area on the IA septum (falx septi) is caused by the fusion of valve of foramen ovale
− Not at the same level as foramen ovale
Discuss the left ventricle
✓ Blood from the LA enters through left AV opening
✓ Blood flows anteriorly, towards the apex
✓ Thickest wall: 8-12 mm
✓ LV pressure: 70-120 mmHg
✓ Apex belongs to left ventricle
✓ Muscular ridges: Trabecula carnea
✓ Anterior and posterior papillary muscles
Discuss the mitral (bicuspid) valve
✓ Left AV orifice is closed by mitral (bicuspid) valve
✓ Consists of 2 cusps: anterior and posterior
✓ Bases of the cusps are attached to left fibrous ring (anulus fibrosus)
✓ Chorda tendinea extend between their free margins and papillary muscles
Discuss the aortic valve
✓ Aortic vestibule is the outflow tract of LV
✓ Blood in the LV is ejected into the aorta
✓ Blood flows upwards, backwards and to the right side through this valve
✓ Aortic orifice is closed by aortic valve ✓ Consists of 3 semilunar cusps: Right,
left, posterior
✓ Between the superior surface of the cusps and aortic wall are pocket-like aortic sinuses (sinus Valsalvae)
3 semi-lunar cusps at the apex of the aortic vestibule (right and left→coronary, posterior → non-coronary sinus)
What does the structure of the aortic valve mean for the blood supply to the myocardium?
In diastole, the valve is closed, so blood goes to coronary arteries
Describe the structure of the fibrous skeleton of the heart
✓ Heart has a structural support frame formed by a complex set of fibrous rings with connecting areas
✓ Provides a great amount of structural and functional support
✓ 4 fibrous rings (anulus fibrosus) around AV, aortic and pulmonary valves
✓ Between the four rings are two trigones (right and left) and the membranous portions of the IA, IV, and AV septa
Describe the function of the skeleton of the heart
✓ Points of attachment for the cusps
✓ Maintains the patency and integrity of AV
and semilunar orifices
✓ Serves as origin/insertion for atrial and ventricular muscles
✓ Insulates the atria from the ventricles
− Allows independent atrial and
ventricular contraction
− Atrioventricular bundle of His should be the only conduction between them (arrhythmias)
Describe the structure of the cardiac wall
✓ 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
✓ Myocardium
− Atrial musculature
− Ventricular musculature
− Muscles are arranged in spiral and circular bundles
− Originate and insert on fibrous skeleton
✓ Epicardium: Visceral layer of the serous pericardium
What are the four corners of the heart?
✓ 1: Right 3rd costal cartilage – 2 cm right of the midline
✓ 2: Right 6th costal cartilage – 2 cm right of the midline
✓ 3: Left 5th costal cartilage – 7-9 cm left of the midline (apex cordis)
✓ 4: Left 2nd costal cartilage – 3 cm left of the midline
Where are the valves of the heart located in relation to surface anatomy?
✓ Tricuspid valve: Behind the right half of the sternum, at the level of the 4th intercostal space
✓ Mitral valve: Posterior to the articulation between left 4th costal cartilage and the sternum
✓ Pulmonary valve: Posterior to the articulation between left 3rd costal cartilage and the sternum
✓ Aortic valve: Posterior to the sternum, at the level of the 3rd intercostal space
How do the heart valves relate to cardiac auscultation?
They make the noises
✓ The valves open and close due to changes in blood pressure and cause “sounds” when they close
✓ Closure of AV valves causes 1st heart sound
✓ Closure of semilunar valves causes 2nd heart sound
✓ Rapid filling of the ventricle causes 3rd heart sound
✓ Sitting or recumbent position, inspiration, expiration, valsalva manoeuvre, exercise can cause changes in heart sounds
Where is it best to auscultate to hear the tricuspid valve?
(HS1): Best heard just to the left of the lower part of the sternum near the 5th intercostal space
Where is it best to auscultate to hear the mitral valve?
(HS1): Best heard over the apex of the heart in the left 5th intercostal space at the midclavicular line (apex cordis)
Where is it best to auscultate to hear the aortic valve?
(HS2): Best heard over the medial end of the right 2nd intercostal space
Where is it best to auscultate to hear the pulmonary valve?
(HS2): Best heard over the medial end of the left 2nd intercostal space
