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
