The Heart Anatomy II - MED201 - PDF

Anatomy II – MED201  Heart facts Heart pumps over 1 million Fastest heart: American pygmy gallons / year shrew, 1.200bpm Slightly larger than clenched fist Largest heart: blue whale Beats about 115.000 times/d Most heart...

Anatomy II – MED201  Heart facts Heart pumps over 1 million Fastest heart: American pygmy gallons / year shrew, 1.200bpm Slightly larger than clenched fist Largest heart: blue whale Beats about 115.000 times/d Most heart attacks happen on Monday The heart The heart starts beating at around 3-4 weeks of gestation.  Heart Double, self-adjusting suction & pressure pump Serves pulmonary & systemic circulation Has its own pacemaker & regulatory systems Simultaneously drains & sends blood to periphery vessels Body Passage of Blood through the Heart SVC/IVC Right Atrium Right Ventricle Pulmonary Arteries Lungs Pulmonary Veins Left Atrium Body Aorta Left Ventricle Right circulation Left circulation Push Drain circulation Pulmonary Pulmonary Pulmonary artery veins Superior & Aorta circulation Inferior vena Somatic cava Drain Push Capillary bed Size Placed in the thoracic cavity.  Heart R. Lung Aorta L. Lung SVC Heart Diaphragm  The basics enclosed in mediastinum (between 2nd-6th ribs, T5-T8) 4 chamber muscular organ Base Posterior-superior part large vessels Apex inferior-anterior part 5th intercostal space  Position 1/3 2/3 2nd rib 6th rib  Position Vertebral column Sternum Diaphragm Remember the number… 4 basic heart anatomy: 4 chambers 4 borders 4 surfaces 4 valvesinto/ exiting the heart  The 4 chambers of the heart Right and left atria receiving chambers Right and left ventricles pumping chambers Body Passage of Blood through the Heart SVC/IVC Right Atrium Right Ventricle Pulmonary Arteries Lungs Pulmonary Veins Left Atrium Body Aorta Left Ventricle  Heart sulci ❖ Grooves on the surface of the heart ❖ Separate chambers, ventricles ❖ Contain the coronary vessels Anterior/ posterior interventricular sulcus Coronary sulcus RA LA RV LV  Heart sulci Anterior view Coronary sulcus encircles heart marks boundry between atria & ventricles Anterior interventricular sulcus Anterior border between ventricles Posterior interventricular sulcus Posterior border between ventricles  Shape and orientation Pyramid that has fallen over and is resting on one of its sides. The apex of this pyramid projects forward, downward, and to the left The base is opposite the apex and faces in a posterior direction.  Surfaces of the heart The sides of the pyramid: → a diaphragmatic (inferior) surface on which the pyramid rests. → an anterior (sternocostal) surface oriented anteriorly, → a right pulmonary surface → a left pulmonary surface. Surfaces of the heart  Surfaces of the heart Base of the heart ❖ Right atrium ❖ Left atrium → the proximal parts of the great veins (superior and inferior venae cavae & the pulmonary veins).  Surfaces of the heart Apex of the heart ❖ Formed by inferior-lateral part of left ventricle ❖ Posterior to left 5th intercostal space (in adults) ❖ ~ 9 cm (hand’s breadth) from median plane  Surfaces of the heart Anterior surface ❖ Right ventricle, ❖ Right atrium  Surfaces of the heart Inferior surface surface ❖ Left ventricle, ❖ Right ventricle  Surfaces of the heart Right pulmonary surface ❖ Right atrium  Surfaces of the heart Left pulmonary surface ❖ Left ventricle  Borders of the heart Right Border Inferior Border Left Border Superior Border The heart Boarders & Margins For radiological evaluations, a thorough understanding of the structures defining the cardiac borders is critical. - Right border: superior vena cava and the right atrium. - Left border: aortic arch, the pulmonary trunk, and the left ventricle. - Inferior border: right ventricle and the left ventricle at the apex. The heart In lateral views: - Anteriorly: the right ventricle - Posteriorly: the left atrium Body Passage of Blood through the Heart SVC/IVC Right Atrium Right Ventricle Pulmonary Arteries Lungs Pulmonary Veins Left Atrium Body Aorta Left Ventricle Pulmonary circulation Systemic circulation Blood Circulation Atrioventricular Valve Function Semilunar Valve Function  Atria of the heart Atria = receiving chambers of the heart Each atrium has a protruding auricle (increases capacity) Pectinate muscles mark atrial walls Blood enters right atria from SVC & IVC & coronary sinus Blood enters left atria from pulmonary veins  Ventricles of the heart ventricles = discharging chambers papillary muscles & trabeculae carneae muscles mark ventricular walls right ventricle pumps blood into pulmonary trunk left ventricle pumps blood into the aorta  Right atrium General Forms right border Receives venous blood from SVC, IVC & coronary sinus right auricle (ear-like pouch) – increases capacity of atrium  Right atrium Interior Posterior wall: Smooth, site of drainage of SVC, IVC Anterior wall: Rough, muscular Crista terminalis: Ridge that separates the two walls  Right atrium Openings Atrioventricular orifice: Tricuspid valve SVC , IVC opening Coronary sinus opening  Right atrium Other Oval fossa: Obliterated orifice after birth  Right ventricle General Anterior surface, inferior border of the heart Separated from left ventricle with interventricular septum Right Ventricle The right ventricle is located anterior and to the left of the right atrioventricular orifice. Conus arteriosus (infundibulum): The outflow tract of the right ventricle, which leads to the pulmonary trunk.  Right ventricle Openings Orifice to pulmonary trunk (Pulmonary valve) Right atrioventricular orifice (Triscuspid valve)  Right ventricle Interior Trabeculae carneae: Irregular muscular elevation Supraventricular crest: Separates inflow from outflow part  Right ventricle Tricuspid valve 3 cusps Anterior Posterior Septal Tendinous cords Papillary muscles muscular, irregular structures (trabeculae carneae) that have only one end attached to the ventricular surface Conical shape Base: Ventricular walls Tips: tendinous cords (edges of cusps)  Right ventricle Tricuspid valve Papillary muscles (3) Correspond to 3 cusps Prevent separation of cusps & inversion during systole e.g. cusps are prevented from prolapsing (being driven into rt atrium) & backward blood flow Tendinous cords attach to free edges of cusps  Right Ventricle Moderator band: A single specialized trabeculum that forms a bridge between the lower portion of the interventricular septum and the base of the anterior papillary muscle.  Right ventricle Pulmonary valve Closes the opening of the right ventricle into the pulmonary trunk It consists of three semilunar cusps with free edges projecting upward into the lumen of the pulmonary trunk. The cusps are named the left, right, and anterior semilunar cusps. Each cusp forms a pocket-like sinus. After ventricular contraction, the recoil of blood fills these pulmonary sinuses and forces the cusps closed. This prevents blood in the pulmonary trunk from refilling the right ventricle.  Left atrium General Forms most of the base of the heart Thicker than right atrium Left auricle: Increases capacity  Left atrium Openings Pulmonary veins` openings Left atrioventricular orifice (Mitral valve)  Left ventricle General Forms apex, left, diaphragmatic surface Conical shape Walls: Thicker than right, covered with trabeculae carnae  Left ventricle Opening Mitral valve opening: Blood entrance from left atrium Aortic valve opening: Exit to aorta  Left ventricle Mitral valve Left atrioventricular valve Bicuspid valve because it has two cusps (the anterior and posterior cusps). Closes the left atrioventricular orifice during ventricular contraction. The bases of the cusps are secured to a fibrous ring surrounding the opening.  Left ventricle Mitral valve 2 cusps: anterior (larger) & posterior Posterior to sternum level of 4th costal cartilage Each cusp receives tendinous cords from more than 1 papillary muscles  Left ventricle Aortic valve Closes the opening from the left ventricle into the aorta. 3 semilunar cusps with the free edge of each projecting upward into the lumen of the ascending aorta. Between the semilunar cusps and the wall of the ascending aorta are pocket-like sinuses-the right, left, and posterior aortic sinuses.  Left ventricle Aortic valve origin of right coronary artery in the right aortic sinus origin of the left coronary artery is in the left aortic sinus no artery arises from posterior aortic sinus Valves of the heart  Cardiac skeleton A collection of dense, fibrous connective tissue in the form of 4 rings with interconnecting areas. In a plane between the atria and the ventricles. The 4 rings (anulus fibrosus) of the cardiac skeleton surround the two atrioventricular orifices, the aortic orifice and opening of the pulmonary trunk. The interconnecting areas include: - the right fibrous trigone, which is a thickened area of connective tissue between the aortic ring and right atrioventricular ring - the left fibrous trigone , which is a thickened area of connective tissue between the aortic ring and the left atrioventricular ring.  Cardiac skeleton The cardiac skeleton helps maintain the integrity of the openings it surrounds Provides points of attachment for the cusps. Also separates the atrial musculature from the ventricular musculature. (The atrial myocardium originates from the upper border of the rings, whereas the ventricular myocardium originates from the lower border of the rings). Serves as a dense connective tissue partition that electrically isolates the atria from the ventricles. (The atrioventricular bundle, which passes through the anulus is the single connection between these two groups of myocardium). Clinical application Valve stenosis  Clinical application Valve regurgitation (insufficiency)  Function of the heart ❖ The cardiac muscle is a separate type of muscle from skeletal or smooth muscle ❖ Contracts with stimuli from heart conduction system ❖ Sinus atrial node (SA node) ❖ Atrioventricular node (AV node) ❖ Bundle of His ❖ Function altered and regulated from autonomous nervous system (sympathetic/parasympathetic) ❖ Diseases of the conducting system lead to arrythmias  Cardiac conduction system The musculature of the atria and ventricles is capable of contracting spontaneously. of His  Cardiac conduction system The cardiac conduction system initiates and coordinates contraction. of His  Cardiac conduction system The conduction system consists of nodes and networks of specialized cardiac muscle cells organized into four basic components: the sinu-atrial node the atrioventricular node the atrioventricular bundle with its of His right and left bundle branches the subendocardial plexus of conduction cells (the Purkinje fibers). Heart conducting system  Cardiac conduction system Unique distribution pattern of the cardiac conduction system establishes an important unidirectional pathway of excitation/contraction. Of of His  Cardiac conduction system Sinu-atrial node The normal pacemaker of the heart. Generates excitation signals Regulated by inputs from the sympathetic and parasympathetic nerves of the cardiac plexuses. Of of His  Heart conducting system Sinoatrial node at upper end of crista terminalis, near opening of SVC in right atrium = pacemaker of heart, initiates heartbeat altered by autonomic stimulation Sympathetic – speeds up Vagal – slows down  Heart conducting system Atrioventricular node lies in septal wall of right atrium superior & medial to opening of coronary sinus in right atrium receives impulse from SA node and passes to AV bundle blood supply from AV nodal artery, brach of RCA  Heart conducting system Bundle of His Begins at AV node Runs along membranous part of interventricular septum Splits into right & left branches which descend interventricular septum Terminal conducting fibers = purkinje fibers spread out into ventricular walls Clinical application Atrial fibrillation  Heart autonomic innervation Speed up the heart with sympathetic stimulation Increase HR, force of contraction Slow it down with parasympathetic stimulation (X) Decrease HR, force of contraction General sensation is transferred with branches of the sympathetic system Sensory information from baroreceptors and chemoreceptors is transferred with the vagus nerve(X)  Heart autonomic innervation Parasympathetic Cardiac plexus X T1 Sympathetic T2 T3 Cervical g. T4 Sympathetic trunk. Clinical applications Coronary circulation  Coronary circulation General ❖ Ensures arterial supply & venous drainage of the heart ❖ Embedded in fat, inside the various sulci ❖ Between myocardium & epicardium  Coronary circulation Diagram RCA. Right marginal a. Posterior interventricular a.. Anterior interventricular a.. LCA.. Circumflex branch of LCA..  Coronary arteries Origin 1stbranches of the aorta arise from corresponding aortic sinuses just superior to aortic valve course around opposite sides of pulmonary trunk supply both atria & ventricles Coronary circulation Anatomic origin  Right coronary artery Anterior ❖ Origin: Right aortic sinus of ascending aorta ❖ Course: ❖ Right to pulmonary truck ❖ Inside coronary sulcus ❖ Branches: ❖ Branch to SA node ❖ Atrial branch ❖ Anterior branch to RV ❖ Supplies: ❖ Right atrium ❖ Right Ventricle ❖ SA node, AV node ❖ 25-35% of LV  Right coronary artery Posterior ❖ Course: ❖ Inside coronary sulcus ❖ Branches: ❖ Branch to AV node ❖ Posterior interventricular branch ❖ Supplies: ❖ Right ventricle ❖ 25-35% of left ventricle  Right coronary artery SA branch & atrial branch ❖ Origin: Right coronary artery ❖ Course: ❖ Cephalad direction ❖ On surface or right atrium ❖ Branches: ❖ None ❖ Supplies: ❖ Right atrium ❖ SA node  Right coronary artery Anterior branch to RV & Right marginal artery ❖ Origin: Right coronary artery ❖ Course: ❖ Inferior ❖ On surface of RV ❖ Branches: ❖ None ❖ Supplies: ❖ Right ventricle  Right coronary artery Posterior interventricular branch ❖ Origin: Right coronary artery ❖ Course: ❖ Inferior ❖ Interventricular sulcus ❖ Branches: ❖ None ❖ Supplies: ❖ Right ventricle & part of LV ❖ SA node, AV node ❖ Intraventricular septum ❖ Sometimes branch of LCA (30%)  Left coronary artery Anterior ❖ Origin: Left aortic sinus of ascending aorta ❖ Course: ❖ Left between the pulmonary truck and left auricle ❖ Inside coronary sulcus ❖ Branches (2 terminal ): ❖ Anterior intrerventricular artery (or Left Anterior Descending artery- LAD) ❖ Circumflex artery ❖ Supplies: ❖ Left atrium ❖ Left ventricle ❖ Interventricular septum (most of) ❖ Atrioventricular bundle and its branches  Left coronary artery Anterior interventricular artery ❖ Origin: Left coronary artery ❖ Course: ❖ Interventricular sulcus ❖ Branches: ❖ Diagonal branches ❖ Supplies: ❖ Major supplier of LV ❖ Apex of the heart  Left coronary artery Circumflex branch ❖ Origin: Left coronary artery ❖ Course: ❖ On the surface of LV ❖ Branches: ❖ Left marginal artery ❖ Supplies: ❖ Major supplier of LV ❖ Interventricular septum Right & left dominance  Coronary circulation ❖ Anatomical variations are extremely common ❖ Commonest points of variation are supply to SA and AV node ❖ Anastomotic network of the heart is poor Cardiac veins Diagram Coronary sinus Great Middle Small cardiac cardiac cardiac vein vein vein  Coronary circulation Coronary sinus main vein of heart runs left to rt in posterior part of coronary sulcus receives great cardiac vein on left end receives middle cardiac vein & small cardiac vein on right end empties into right atrium  Coronary circulation Great cardiac vein main tributary of coronary sinus also termed anterior interventricular vein ascends into the anterior interventricular sulcus reaches the coronary sulcus empties into left side of coronary sinus  Coronary circulation Middle & small cardiac vein Drain area supplied by the RCA Empty inside the right side of coronary sinus Middle cardiac vein Inside the posterior interventricular sulcus Small cardiac vein Parallel to the Right coronary artery  Coronary circulation Anterior & smallest cardiac veins Drain directly inside the atria Anterior cardiac veins Anterior surface of right ventricle Pass over the coronary sulcus Drain inside right atrium Smallest cardiac veins Valveless minute vessels From capillary beds of myocardium Drainage inside the atria Clinical applications Infarction Clinical applications Stenting Clinical applications Heart by pass Surface anatomy 2nd intercostal 3rd cartilage 5th intercostal 6th cartilage  Surface anatomy Tricuspid valve: left of the lower part of the sternum near the fifth intercostal space. Mitral valve: left fifth intercostal space at the midclavicular line. Pulmonary valve: medial end of the left second intercostal space. Aortic valve: right second intercostal space Questions?