2. Internal features of the heart.pdf

Internal features of the heart Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt Dr. Nora Helal  Intended Learning Outcomes (ILOs) 1. Describe the interior of the heart chambers. 2. Describe th...

Internal features of the heart Department of human Anatomy and Embryology Faculty of Medicine Mansoura National University, Egypt Dr. Nora Helal  Intended Learning Outcomes (ILOs) 1. Describe the interior of the heart chambers. 2. Describe the heart Valves (atrioventricular & semilunar). 3. Correlate surface anatomy of the heart and valves with anatomical position.  Agenda 1. Describe the interior of the heart chambers? 2. Describe the heart Valves (atrioventricular & semilunar)? 3. Correlate surface anatomy of the heart and valves with anatomical position?  Internal Features of the heart A. Right atrium: the interior of the right atrium shows: 3 walls, crista terminalis and orifices. ▪ Crista terminalis: Vertical ridge on the lateral wall of the atrium extending from the opening of SVC to IVC. Corresponds to the sulcus terminalis on the outer surface. Separates the rough anterior part from the smooth posterior part.  Internal Features of the heart ▪ Walls: ✓ Anterior wall: rough due to presence of musculi pectinati (muscular ridges extending from the crista terminalis). ✓ Posterior wall (sinus venarum): smooth and receives the following orifices: SVC: in the upper part of the posterior wall. Has no valve. IVC: in the lower part of the posterior wall. Has a valve. Coronary sinus: lies between the orifice of IVC and the tricuspid orifice. Has a valve. ✓ Septal wall: formed by the interatrial septum and shows: Fossa ovalis: ✓ oval depression in the lower part of the wall. ✓ Represents the septum primum of the fetus. Annulus ovalis: ✓ The crescentic margin of the fossa ovalis. ✓ Represents the lower margin of septum secundum of the fetus. N.B. The right auricle is a conical projection from the anterior wall to increase the capacity of the atrium.  Internal Features of the heart Orifices: Orifices in the posterior wall: SVC, IVC & coronary sinus. Openings of anterior cardiac veins. Right atrio-ventricular (A-V) orifice: lies between the right atrium and right ventricle.  Internal Features of the heart B. Left atrium: the interior of the left atrium differs from the right atrium in the following features: ▪ Crista terminalis: absent. ▪ Musculi pectinati are confined only to the auricle. ▪ The posterior wall shows the orifices of the four pulmonary veins (has no valves). ▪ The septal wall has no fossa ovalis or annulus ovalis. ▪ The mitral orifice connects the left atrium to the left ventricle.  Quiz What separates the rough part and the smooth part of the right atrium? A) Musculi pectinati B) Fossa Ovalis C) Annulus ovalis D) Crista Terminalis E) Right auricle Answer: D  Internal Features of the heart C. Right ventricle: the interior of the right Infundibulum ventricle is divided into 2 parts (inflowing and outflowing) separated by supraventricular crest. Outflowing part (infundibulum): Lies above the supraventricular crest. Smooth. Leads to the pulmonary trunk.  Internal Features of the heart Inflowing part: Lies below the supraventricular crest. Rough. Shows the following features: Trabeculae carneae: irregular muscular projections. Papillary muscles: they have the following features: ✓ Number: three. ✓ Arrangement: anterior, posterior and septal. ✓ Shape: each muscle is conical in shape having:  Base: attached to the corresponding wall of the ventricle.  Apex: projects to the lumen of the ventricle and attached Posterior papillary muscle to the cusps of tricuspid valve by chordae tendinae.  Internal Features of the heart Anterior papillary muscle:  It is the largest.  Arises from the anterior wall. Posterior papillary muscle:  It is smaller than the anterior.  Arises from the posterior wall. Septal papillary muscle:  It is the smallest.  Arises from the interventricular septum. Function: papillary muscles prevent eversion of the cusps of tricuspid valve into the atrium during ventricular systole (prevents tricuspid regurge).  Internal Features of the heart Moderator band: Muscular band that extends from the lower part of the interventricular septum to the base of anterior papillary muscle. It prevents overdistention of the right ventricle and carries the right branch of AV bundle. Orifices: the right ventricle has 2 major orifices; tricuspid (right AV orifice) and pulmonary orifice. Moderator band  Internal Features of the heart D. Left ventricle: the interior of the left ventricle Left ventricle differs from the right ventricle in the following features: ▪ The wall of the left ventricle is 3 times thicker than that of the right ventricle. ▪ The outflowing part (aortic vestibule) is smooth and leads to the ascending aorta. ▪ Has no moderator band. ▪ Papillary muscles: o They are 2 (anterior and posterior). o They are larger and thicker than those of the right ventricle. o Their chordae tendinae are attached to both cusps of the mitral valve. ▪ Orifices: The left ventricle has 2 major orifices; mitral (left AV orifice) and aortic orifice.  Internal Features of the heart Compare between right & left ventricles Right ventricle R Left ventricle L Wall thinner 3 times thicker Cross section Semilunar Circular Outflow part Infundibulum Aortic vestibule Papillary 3 (Anterior, posterior, septal) 2 (Anterior, posterior) muscles Moderator Present Absent (No moderator band) band Valves 2 (Tricuspid, pulmonary) 2 (Mitral, aortic)  Quiz Muscles of the ventricles responsible for pumping blood are called… A) Musculi pectinati B) Papillary muscles C) Tracbeculae Carnae D) Cordae Tendineae E) Moderator band Answer: C  Valves of the heart Atrioventricular valves Semilunar valves  Valves of the heart Semilunar valves The pulmonary valve on the right and the aortic valve on the left. Both have the following features: ✓ The orifices are circular in shape. ✓ Surrounded by a fibrous tissue ring of the fibrous skeleton of the heart. ✓ Open during systole and close during diastole. ✓ Have 3 cusps that are semilunar in shape: with the base attached to the fibrous ring and free margin. ✓ Their cusps are double layers of endothelium with fibrous tissue in between. ✓ The roots of the vessels show dilatations (Sinuses) opposite each cusp.  Valves of the heart Semilunar valves The pulmonary valve on the right and the aortic valve on the left. Both have the following features: ✓ The orifices are circular in shape. ✓ Surrounded by a fibrous tissue ring of the fibrous skeleton of the heart. ✓ Open during systole and close during diastole. ✓ Have 3 cusps that are semilunar in shape: with the base attached to the fibrous ring and free margin. ✓ Their cusps are double layers of endothelium with fibrous tissue in between. ✓ The roots of the vessels show dilatations (Sinuses) opposite each cusp.  Valves of the heart Comparison between the semilunar valves Pulmonary Aortic valve valve Between the right Between the left ventricle and ventricle and pulmonary trunk ascending aorta. A Has 3 cusps: L R Has 3 cusps: right coronary, left LC anterior, right and NC RC coronary and non- left coronary Size of the orifice: 3 Size of the orifice: 2 cm cm Surface anatomy: Surface anatomy: at the left margin of left 3rd sternocostal sternum opposite the junction 3rd intercostal space  Valves of the heart Atrioventricular valves: ▪ The tricuspid valve on the right & the mitral valve on the left. ▪ Both have the following features: The orifices are oval in shape. Surrounded by a fibrous tissue ring of the fibrous skeleton of the heart. Open during diastole and close during systole. Have cusps that are triangular in shape: with the base attached to the fibrous ring and the free margin attached to chordae tendinea. Their cusps are double layers of endothelium with fibrous tissue inbetween.  Valves of the heart Comparison between the atrioventricular valves Tricuspid valve Mitral valve Between the right Between the left atrium atrium and right and left ventricle ventricle Has 3 cusps: anterior, Has 2 cusps: anterior posterior and septal and posterior Admits 3 fingers Admits 2 fingers A S A Surface anatomy: P P lies at the midline of lies behind the left half the sternum opposite of sternum opposite the 4th intercostal the 4th costal cartilage. space  Fibrous skeleton of the heart ▪ It is formed of two 8-shaped rings surrounding the major 4 orifices of the heart. ▪ They give attachment to the cusps of AV and semilunar valves.  Interventricular septum ▪ It separates the right ventricle from the left ventricle. ▪ Its upper part is membranous while its lower part is muscular. ▪ It is concave towards the left ventricle and convex towards the right ventricle.  Surface anatomy of the heart Draw 4 points on the thoracic wall as follow: ▪ Point A: at the lower border of left 2nd costal cartilage 1.5 cm from the sternal margin. ▪ Point B: at the upper border of the right 3rd costal cartilage 1.5 cm from the sternal margin). ▪ Point C: at the right 6th costal cartilage 2 cm from the sternal margin. ▪ Point D: at the apex of the heart (left 5th intercostal space 3.5 inch (9 cm) from the midline.  Surface anatomy of the heart Borders of the heart are drawn as follow: ▪ Upper border: straight line connecting points A and B. ▪ Right border: curved line convex to the right connecting points B and C. ▪ Lower border: straight line connecting points C and D. ▪ Left border: curved line convex to the left connecting points D and A.  Surface anatomy of the heart Surface markings of cardiac valves: ▪ Pulmonary valve: at the left 3rd costal cartilage at its junction with sternum. ▪ Aortic valve: opposite the 3rd intercostal space at the left margin of sternum. ▪ Mitral valve: opposite the left 4th costal cartilage behind left half of sternum. ▪ Tricuspid valve: opposite the 4th intercostal space at the midline of the sternum.