Cardiac Nerve Supply, Arterial Supply, Venous Drainage, and Surface Anatomy PDF

(004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY...

(004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 Comes from Autonomic Nervous System (ANS): OUTLINE 1. Sympathetic nerve supply I. HEART NERVE SUPPLY from upper thoracic spinal cord segments → routes thru cervical and upper thoracic sympathetic chain ganglia A. Extrinsic Nerve Supply → descends thru sympathetic cervical and thoracic B. Intrinsic Nerve Supply cardiac nerves → enters cardiac plexuses (below arch of aorta around base of the heart) → postganglionic II. HEART ARTERIAL SUPPLY fibers terminate in: A. Right Coronary Artery a. sinoatrial & atrioventricular nodes B. Left Coronary Artery b. cardiac muscle fibers c. coronary arteries C. Coronary Artery Variations 2. Parasympathetic nerve supply D. Arterial Supply to the Conducting from Vagal cardiac nerve branches (arise in the neck, System descend into thorax, and join into the cardiac plexuses) → postganglionic parasympathetic fibers: E. Coronary Artery Anastomoses a. sinoatrial and ventricular nodes III. VENOUS DRAINAGE OF THE HEART b. coronary arteries IV. SURFACE ANATOMY OF THE HEART Effects: Bradycardia and Vasoconstriction A. Large Arteries of the Thorax B. Large Veins of the Thorax. C. Lymph Nodes If Afferent fibers course along the Sympathetic fiber, the brain is not I. HEART NERVE SUPPLY conscious about it. Normally, the innervation does not reach consciousness. Unless there is a low coronary artery flow detected by the afferent fiber, then that’s the time it reaches consciousness Extrinsic and intrinsic networks innervate the heart. Both (feeling of pain). Thus, in a normal arterial flow, one cannot feel the sympathetic and parasympathetic fibers of the autonomic beating or the systole and diastole of the heart. But, in low coronary nervous system form the extrinsic nerve supply. The artery flow, e.g. Myocardial infarction, one feels chest pain. conducting system of the heart forms the intrinsic nerve tract. A. EXTRINSIC NERVE SUPPLY If Afferent fibers course along the Parasympathetic fiber, it acts on the cardiovascular reflexes. B. INTRINSIC NERVE SUPPLY 1. Definition Also known as the Conducting System of Heart Network of specialized cardiac muscle cells Designed to generate rhythmic cardiac impulses Conduct and coordinate the intrinsic contractions of the myocardium Normal heart contracts 70 – 90 bpm (beats per minute) o Other books: 60 – 100 bpm but if patient has cardiac disease, we would like to have a very low heart beat which is 50 – 60 bpm because anything beyond 70 bpm may cause congestive heart failure. (Thus, target bpm depends on case of patient.) 2. Functions of the Conducting System Initiate excitation of the atria. This is the “pacemaker function.” Delay excitation of the ventricles The slight delay in the passage of the impulse from the atria to the ventricles allows time for the atria to empty Figure 1. The external innervation of heart showing parasympathetic and sympathetic pathway Page 1 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 their blood into the ventricles before the ventricles contract. attributed to the internodal pathways that are consisting of Penetrate the fibrous cardiac skeleton purkinje fibers and ordinary cardiac muscle Spread excitation across the ventricles - Anterior internodal pathway a. Sinuatrial Node o leaves the anterior end of SA node and passes to the superior vena cava opening Located at the wall of right atrium at the junction of crista terminalis and superior vena cava o descend to atrial septum and ends on AV node Origin of spontaneous rhythmic electrical impulses Middle internodal pathway o leaves the posterior end of the SA node and “Pacemaker” of the heart passes posterior to the SVC opening Slow conduction velocity ( ~1 m/s) o descends to the atrial septum to the AV node - But heart rate is about 70-90 bpm (70-100 bpm in other books) Posterior internodal pathway o leaves posterior part of SA node Derived from embryonic sinus venosus o descend to the crista terminalis and the valve Normally, heart rate depends on the SA node, but autonomic input modulate SA node to balance of the inferior vena cava to the AV node heart rate b. Atrioventricular Node located at lower right side of atrial septum btw. The attachment of the septal cusp of the tricuspid valve and opening of coronary sinus slow speed of conduction (.1s) delays impulse from atria to ventricle which give sufficient time for atria to empty blood c. Atrioventricular Bundle (Bundle of His) originate from AV node, descend behind septal cusp of tricuspid valve and extend into the membranous part of the ventricular septum pierces the fibrous skeleton of the heart sole myocardial connection between atria and ventricle and only route of impulse from atria to ventricle Bundle Branches - Right bundle branch à ventricular septum à moderator band à anterior wall of right ventricle Figure 2. Conducting system of the heart - Left bundle branch à ventricular septum à divides into two branches, anterior and posterior II. HEART ARTERIAL SUPPLY d. Purkinje Fibers The coronary arteries are attached to your aorta. The aortic cusps will give off your left and right coronary arteries; right main coronary terminal branch of conducting system artery is given off by the right coronary cusps (cc), and left CA by plexiform fashion the left CC. highest conduction velocity (4-5m/s) A. Right coronary artery – binds over and passes through the if SA node malfunctions, AV node takeover, right atrioventricular groove thus heart rate is slower B. Left coronary artery – divide into circumflex branch, passes if patient have coronary disease (specially through left atrioventricular groove. Another part (anterior right coronary disease) there will be slowing interventricular branch) will descend into anterior of conduction à purkinje will take over as interventricular groove. pacemaker, heart beat at around 30-40 not effective in pumping of ventricle patient will have decompensated heart failure à death e. Internodal Conduction Pathways impulses from the SA node travel to AV node faster than they can travel along the myocardium Page 2 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 3. Posterior ventricular branches – supply the diaphragmatic surface of the RV. One of these, the atrioventricular nodal branch, supplies the AV node 4. Posterior interventricular (descending artery) - posterior part of the ventricular septum but not to the apical part; supplies the AV node (90%) Runs toward the apex in the posterior interventricular groove. It gives off branches to the right and left ventricles, including its inferior wall. It supplies branches to the posterior part of the ventricular septum but not to the apical part, which receives its supply from the anterior interventricular branch of the left coronary artery. The posterior interventricular artery usually is a branch of the right coronary artery. However, it may originate from the circumflex branch of the left coronary artery. 5. Atrial branches – supply the anterior and lateral surfaces of Figure 3. The major arteries of the heart the right atrium; posterior wall of left and right atria. One branch supplies the posterior surface of both right and left A. RIGHT CORONARY ARTERY atria. Sinuatrial node artery- 35% arises from LCA Supplies most of the right atrium Most of the right ventricle Left ventricle (diaphragmatic surface) Ventricular septum (posterior third) Most of the SA Node (-60% of the people) AV node (-80% of the people) If the patient has myocardial infarction affecting the coronary artery, those people with predominantly having conducting system or pacemaker as the SA node, then the patient might have bradycardia because the SA and AV node will have a decrease blood supply coming from the CA. Aside from bradycardia, the patient may have cardiac arrhythmia. They are prone to premature ventricular complexes and AV blockage manifested in patients with myocardial infarction. From anterior aortic sinus Run to the right side between the pulmonary trunk and right auricle. Figure 4. Branches of the coronary arteries and veins Descends vertically in the right AV groove Inferior border or the heart. Continues posteriorly along with AV groove to anastomose with left coronary artery in the posterior interventricular groove. Sometimes, the distal end of the right coronary artery will anastomose with the left anterior descending artery or the left circumflex in the AV groove Ø BRANCHES OF THE RIGHT CORONARY ARTERY 1. Right conus artery –first branch, supplies the anterior surface pulmonary conus and upper part of the anterior wall of RV 2. Anterior ventricular branches – anterior surface of the RV A. Marginal Branch – lowest part B. The right marginal artery is the largest and runs along the right margin of the anterior surface toward the apex Figure 5. Branches of the right coronary artery Page 3 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 3. Anterior ventricular and posterior ventricular branches B. LEFT CORONARY ARTERY supply the left ventricle 4. Atrial branches supply the left atrium Mainly supplies the left atrium Most of the left ventricle Small part of the right ventricle Ventricular septum (anterior two thirds) – posterior one third will be supplied by the right coronary artery SA node (-40% of people) AV bundle + bundle branches Figure 6. Branches of the left coronary artery C. CORONARY ARTERY VARIATIONS Figure 4. Branches of the coronary arteries and veins Variations in the pattern of blood supply to the heart occur commonly, and Most affect the blood supply to the Usually larger than the right coronary artery, supplies the major diaphragmatic surface of both ventricles. The condition known part of the heart. as coronary artery dominance refers to the variable Origin of the Left aortic sinus - run to the left between the pulmonary trunk & posterior interventricular artery left auricle 1. Right Dominance Atrioventricular groove and divides into an anterior interventricular The posterior interventricular artery is a large branch of the branch and a circumflex branch right coronary artery. Right dominance is present in most individuals (~67%). Ø BRANCHES OF THE LEFT CORONARY ARTERY 1. Anterior Interventricular (descending) branch Anterior interventricular groove to the apex of the heart. It then passes around the apex of the heart to enter the posterior interventricular groove and anastomoses with the terminal branches of the right coronary artery. 1/3 of individuals ends at the apex of the heart Supplies the right and left ventricles. Supplies the anterior part of the ventricular septum. Left diagonal artery may arise directly from the trunk of the left coronary artery. A small left conus artery supplies the pulmonary conus. 2. Circumflex artery Same size as the anterior interventricular artery Winds around the left margin of the heart in the atrioventricular groove Left marginal artery is a large branch that supplies the Figure 7. Posterior View of the heart Showing the left margin of the left ventricle down to the apex origin and distribution of the posterior interventricular artery in the right dominance. Page 4 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 2. Left Dominance In left dominance, the posterior interventricular artery is a D. ARTERIAL SUPPLY OF THE CONDUCTING branch of the Circumflex branch of the left coronary artery (~15%). SYSTEM Right coronary artery arises from the anterior aortic sinus of the ascending aorta and runs forward between the pulmonary trunk and the right auricle. The Left coronary artery, supplies the major part of the heart including the greater part of the left atrium, left ventricle, and ventricular septum. It arises from the left posterior aortic sinus of the ascending aorta and passes forward between the pulmonary trunk and the left auricle Figure 8. Posterior view of the heart showing the origin and distribution of the posterior interventricular artery in the left dominance. 3. Codominance In codominance (~18%), both the right coronary and circumflex arteries contribute to the formation of the posterior interventricular artery or to multiple branches that substitute for that vessel. Table 1. Typical Distributions of the Coronary Arteries. E. CORONARY ARTERY ANASTOMOSES Anastomoses (collateral circulation) between the terminal branches of the Right and left coronary arteries do exist; however, they are usually not large Enough to provide an adequate blood supply to the cardiac muscle should one Of the large branches become blocked by disease. Thus, the coronary arteries Are generally considered to be functional end arteries. A sudden block of One of the larger branches of either coronary artery usually leads to Myocardial death (myocardial infarction), although sometimes the collateral Circulation is enough to sustain the muscle. Figure 9. Anterior view of the heart showing the relationship of the blood supply to the conducting system. Page 5 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 Table 2. Major Coronary Veins and Accompanying coronary arteries Not all venous blood drains into the coronary sinus. A variable number of small anterior cardiac veins drain the anterior surface of the heart and empty directly into the right atrium. Other very small veins may drain directly into the chambers of the heart (usually the atria). Figure 11. Coronary artery anastomoses III. VENOUS DRAINAGE OF THE HEART - Most blood from the heart wall drains into the right atrium via the coronary sinus. - The coronary sinus is a large, dilated vein that lies in the posterior part of the atrioventricular groove (coronary sulcus). o It empties into the right atrium just to the left of the inferior vena cava Table 3. Coronary Artery Lesions, Infarct Location, and ECG Signature IV. SURFACE ANATOMY OF THE HEART Figure 12. Venous drainage of the heart Ø Three Main Veins: - drain the heart wall and open into the coronary sinus - each of these typically accompanies a specific coronary artery. The great cardiac 1. Great cardiac vein o vein drains most of the areas of the heart supplied by the left coronary artery and joins the left end of the coronary sinus. 2. Middle cardiac vein 3. Small cardiac vein o The middle and small cardiac veins drain most of the areas normally supplied by the right coronary artery and drain into the right end of the coronary Figure 13. Four valves of the heart sinus. Page 6 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 Tricuspid valve - lies behind the right half of the sternum opposite the 4th intercostal space Mitral valve - behind the left half of the sternum opposite the 4th costal cartilage. Pulmonary valve - behind the medial end of the third left costal cartilage & adjoining part of sternum Aortic valve - behind the left half of the sternum opposite the 3rd intercostal space. Figure 14. Anterior view of the thoracic aorta Table 3. Comparison of Anatomic and Auscultation Areas of the Cardiac Valves A. LARGE ARTERIES OF THE THORAX 1. Aorta a. Ascending – Right Coronary Artery and Left Coronary Artery - As the aorta ascends it will give rise to the aortic arch first the: o Brachiocephalic artery – 1st branch o right subclavian artery – supplies the right upper arm o right common.carotid artery – supplies the brain o Left common carotid artery -2nd branch, gives rise to internal and external carotid artery o Left subclavian artery -3rd branch, supplies the right upper arm Figure 15. Anterior view of the abdominal aorta b. Descending - thoracic aorta o posterior intercostal artery o subcostal artery B. LARGE VEINS OF THE THORAX o pericadial, esophageal, bronchial arteries They receive blood drainage from the head, neck, upper limbs, and 2. Pulmonary trunk - left and right pulmonary artery, thorax. The inferior vena cava receives blood mainly from the body ligamentum arteriosum > abdominal aorta below the diaphragm and has only a brief appearance in the thorax. 1. Pulmonary Trunk (within the heart) 2. Brachiocephalic Veins The right and left brachiocephalic veins form at the root of the neck on each side by the union of the respective subclavian and internal jugular veins. The left brachiocephalic vein passes obliquely downward and to the right behind the manubrium sterni Page 7 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 and in front of the large branches of the aortic arch. The right c. Superior Hemiazygos Vein brachiocephalic vein is relatively short and descends almost - formed by the union of left superior vertically. The two brachiocephalic veins join to form the intercostal vein and the fourth to the eighth superior vena cava. intercostal veins. It joins the azygos vein at the level of the seventh thoracic vertebra. 5. Inferior Vena Cava pierces the central tendon of the diaphragm opposite the eighth thoracic vertebra and almost immediately enters the lowest part of the right atrium Ø Venous return (from the inferior part of the body) Tibioperoneal trunk à Popliteal area à Common femoral vein à Iliac vein à inferior vena cava (which has branches also wherein venous flow coming from the different parts of the abdominal system) à the central tendon à the right atrium Figure 15. Major veins draining the superior and inferior venae cavae 3. Superior Vena Cava drains the upper part of the body passes downward to end in the right atrium of the heart The azygos vein joins the posterior aspect of the superior vena cava just before it enters the pericardium. 4. Azygos Veins drain the posterior circulation in the thorax, pericardium and others Consists of: a. Main Azygos Vein - formed by the union of the right ascending lumbar vein and the right subcostal vein in the abdomen - It ascends through the aortic opening in the diaphragm on the right side of the aorta up to Figure 16. Veins of internal thoracic wall the level of the fifth thoracic vertebra. Here, it arches forward above the root of the right lung to empty into the posterior surface of the C. LYMPH NODES superior vena cava. b. Inferior Hemiazygos Vein The lymph vessels in the thorax collect lymph from virtually all - formed by the union of the left ascending parts of the body below the neck and upper limbs. Further, the lumbar vein and the left subcostal vein in upper ends of these vessels (located in the root of the neck) the abdomen often forms the inferior typically collect the drainage from the head, neck, and upper hemiazygos vein. It ascends through the left limbs. crus of diaphragm and, at about the level of 1. Thoracic wall the eighth thoracic vertebra, turns to the right Thoracic wall nodes drain in the bronchomediastinal and joins the azygos vein. It receives as trunk while posterior intercostal node will drain into the tributaries some lower left intercostal veins thoracic trunk. and mediastinal veins. Page 8 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 a. Anterior axillary nodes - drain the lymph vessels of the skin of the anterior thoracic wall b. Posterior axillary nodes - drain the lymph vessels of the skin of the posterior thoracic wall c. Internal thoracic nodes - drain the deep lymph vessels of the anterior parts of the intercostal space. From here, the lymph enters the thoracic duct. 2. Thoracic duct begins below in the abdomen as a dilated sac, the cisterna chyli gradually crosses the median plane behind the esophagus and reaches the left border of the esophagus (T4 Level) Here, it bends laterally behind the carotid sheath and in front of the vertebral vessels All of the drainage in the left and what’s below half of the body will be drained into the cisterna chyli and then drained into the right atrium It turns downward in front of the left phrenic nerve and crosses the subclavian artery to enter the beginning of the brachiocephalic vein Figure 18. Lymph vessels and nodes of posterior abdominal wall TEST YOUR KNOWLEDGE 1. If the SA node will malfunction which will become pacemaker of heart A. Sinoatrial node B. Atrioventricular node C. Purikinje fibres D. Bundle of His 2. What is/are the nerve supply of the heart? A. Sympathetic nerves B. Brachial plexus C. Parasympathetic nerves D. Both A and C 3. The first branch of aorta is called A. Brachiocephalic artery B. Left common carotid artery Figure 17. Distribution of lymphatic vessels and C. Left subclavian artery lymph nodes D. Subcoastal artery 4. Where is the auscultation location of aorta? A. Over the right half of lower end of the body of the sternum B. Over the medial end of second right intercoastal space C. Over the medial end of second left intercoastal space Page 9 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 5. Identify which coronary venous drains into right atrium 13. A 54-year-old patient is implanted with an artificial cardiac A. Azygous vein pacemaker. Which of the following conductive tissues of the B. Aorta C. Coronary sinus heart had a defective function that required the pacemaker? D. Inferior vena cava A. Atrioventricular (AV) bundle B. AV node 6. Most common dominance seen in humans are C. Sinoatrial (SA) node A. Left dominance D. Purkinje fiber B. Right dominance E. Moderator band C. Co-dominance 14. An 83-year-old man with a typical coronary circulation has 7. Which internodal pathway drains through crista terminalis? been suffering from an embolism of the circumflex branch of A. Anteriorly internodal pathway the left coronary artery. This condition would result in B. Middle internodal pathway ischemia of which of the following areas of the heart? C. Posterior internodal pathway A. Anterior part of the left ventricle B. Anterior interventricular region 8. Which coronary artery supplies most of the SA node and AV C. Posterior interventricular region node D. Posterior part of the left ventricle A. Right coronary artery E. Anterior part of the right ventricle B. Left coronary artery 15. A 44-year-old man with a stab wound was brought to the 9. Anatomical location of pulmonary valve emergency department, and a physician found that the patient A. lies behind left half of the sternum. was suffering from a laceration of his right phrenic nerve. B. lies behind medial end of third coastal cartilage and adjoining Which of the following conditions has likely occurred? part of sternum. A. Injury to only GSE fibers C. over the right half of lower end of the body of the sternum B. Difficulty in expiration D. lies behind right half of the sternum. C. Loss of sensation in the fibrous pericardium and mediastinal pleura 10. 32-year-old patient who weighs 275 lb comes to the doctor’s D. Normal function of the diaphragm office. On the surface of the chest, the physician is able to E. Loss of sensation in the costal part of the diaphragm locate the apex of the heart: A. At the level of the sternal angle 16. A 37-year-old patient with severe chest pain, shortness of B. In the left fourth intercostal space breath, and congestive heart failure was admitted to a local C. In the left fifth intercostal space hospital. His coronary angiograms reveal a thrombosis in the circumflex branch of the left coronary artery. Which of the D. In the right fifth intercostal space following conditions could result from the blockage of blood E. At the level of the xiphoid process of the sternum flow in the circumflex branch? A. Tricuspid valve insufficiency 11. A 27-year-old cardiac patient with an irregular heartbeat visits B. Mitral valve insufficiency her doctor’s office for examination. Where should the C. Ischemia of AV node physician place the stethoscope to listen to the sound of the D. Paralysis of pectinate muscle mitral valve? E. Necrosis of septomarginal trabecula A. Over the medial end of the second left intercostal space B. Over the medial end of the second right intercostal space 17. The attending faculty in the coronary intensive care unit C. In the left fourth intercostal space at the midclavicular line demonstrates to his students a normal heart examination. The D. In the left fifth intercostal space at the midclavicular line first heart sound is produced by near simultaneous closure of E. Over the right half of the lower end of the body of the sternum which of the following valves? A. Aortic and tricuspid B. Aortic and pulmonary 12. A 19-year-old man came to the emergency department, and C. Tricuspid and mitral his angiogram exhibited that he was bleeding from the vein D. Mitral and pulmonary that is accompanied by the posterior interventricular artery. E. Tricuspid and pulmonary Which of the following veins is most likely to be ruptured? A. Great cardiac vein 18. A 27-year-old patient with Marfan’s syndrome has an B. Middle cardiac vein aneurysm of the aortic arch. This may compress which of the C. Anterior cardiac vein following structures? D. Small cardiac vein A. Right vagus nerve E. Oblique veins of the left atrium B. Left phrenic nerve C. Right sympathetic trunk D. Left recurrent laryngeal nerve E. Left greater splanchnic nerve Page 10 of 11 CMED 1A  (004) CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY DR. LESLIE ASUNCION-VIADO| 01/11/21 19. A 46-year-old male patient with high blood pressure was examined in the emergency department, and his physician 18. D. The left recurrent laryngeal nerve loops around the arch of the aorta near the ligamentum arteriosum, whereas the right recurrent laryngeal nerve hooks found a leakage of blood from the blood vessel that normally around the right subclavian artery. All other nerves are not closely associated carries richly oxygenated blood. Which of the following vessels with the aortic arch. would most likely be damaged? A. Superior vena cava 19. C. Pulmonary veins return oxygenated blood to the heart from the lungs. B. Pulmonary arteries Pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygen renewal. The portal vein carries deoxygenated blood with nutrients C. Pulmonary veins from the intestine to the liver. The superior vena cava and coronary sinus carry D. Portal vein deoxygenated blood to the right atrium. E. Coronary sinus ANSWERS REFERENCES 1. Wineski, Lawrence E. (2019). Snell’s Clinical Anatomy By Regions. (10th ed.). Philadelphia: Wolters Kluwer. 1. A. Atrioventricular node 2. D. Sympathetic and parasympathetic nerves are the extrinsic nerve supply of 2. Netter, Frank H. (2019). Atlas of Human Anatomy. (7th ed.). the heart. Philadelphia: Elsevier Inc. 3. A. Brachiocephalic artery 3. Chung, K.W., Chung, H.M., & Halliday, N.L. (2011). BRS Gross 4. B. Over the medial end of second right intercostal space Anatomy. (7th ed.). Philadelphia: Lippincott Williams &Wilkins. 5. C. Coronary sinus 6. B. Right Dominance 4. Viado, L.A. (2021). Cardiovascular Anatomy Part 2. [PPT] 7. C. Posterior internodal pathway 8. A. Right coronary artery 9. B. Lies behind medial end of third costal cartilage and a adjoining part of sternum 10. C. On the surface of the chest, the apex of the heart can be located in the left fifth intercostal space slightly medial to the midclavicular (or nipple) line. The sternal angle is located at the level where the second ribs articulate with the sternum. The xiphoid process lies at the level of T10 vertebra. 11. D. The mitral valve (left atrioventricular [AV] valve) produces the apical beat (thrust) of the heart, which is most audible over the left fifth intercostal space at the midclavicular line. The pulmonary valve is most audible over the medial end of the second left intercostal space, the aortic valve is most audible over the medial end of the second right intercostal space, and the right AV valve is most audible over the right half of the lower end of the body of the sternum. 12. B. The middle cardiac vein ascends in the posterior interventricular groove, accompanied by the posterior interventricular branch of the right coronary artery. The great cardiac vein is accompanied by the anterior interventricular artery, the anterior cardiac vein drains directly into the right atrium, and the small cardiac vein is accompanied by the marginal artery. 13. C. The sinoatrial (SA) node initiates the impulse of contraction and is known as the pacemaker of the heart. Impulses from the SA node travel through the atrial myocardium to the AV node and then race through the AV bundle (bundle of His), which divides into the right and left bundle branches. The bundle breaks up into terminal conducting fibers (Purkinje fibers) to spread out into the ventricular walls. The moderate band carries the right limb of the AV bundle from the septum to the sternocostal wall of the ventricle. 14. D. The circumflex branch of the left coronary artery supplies the posterior portion of the left ventricle. The anterior interventricular artery supplies the anterior aspects of the right and left ventricles and the anterior interventricular septum. 15. C. The phrenic nerve supplies the pericardium and mediastinal and diaphragmatic (central part) pleura and the diaphragm, an important muscle of inspiration. It contains general somatic efferent (GSE), general somatic afferent (GSA), and GVE (postganglionic sympathetic) fibers. The costal part of the diaphragm receives GSA fibers from the intercostal nerves. 16. B. The circumflex branch of the left coronary artery supplies the left ventricle, and thus its blockage of blood flow results in necrosis of myocardium in the left ventricle, producing mitral valve insufficiency. The pectinate muscles, tricuspid valve, and septomarginal trabecula are present in the right atrium and ventricle. 17. C. The first heart sound (“lub”) is produced by the closure of the tricuspid and mitral valves, whereas the second heart sound (“dub”) is produced by the closure of the aortic and pulmonary valves. Page 11 of 11 CMED 1A