ANAT_LC6b_HEART.pdf

UNIVERSITY OF NORTHERN PHILIPPINES ANATOMY LC7 CARDIAC NERVE SUPPLY, ARTERIAL COLLEGE OF MEDICINE, BATCH...

UNIVERSITY OF NORTHERN PHILIPPINES ANATOMY LC7 CARDIAC NERVE SUPPLY, ARTERIAL COLLEGE OF MEDICINE, BATCH 2026 SUPPLY, VENOUS DRAINAGE, AND Transcribers: Achacoso, Acosta, Ammiyao, Anulacion, Avecilla, Busaing SURFACE ANATOMY Editors: Abaday, Baltazar, Cabillo, Sadiasa Dr. L. Asuncion- Viado | Dec 2022 COURSE OUTLINE b. PARASYMPATHETIC NERVE SUPPLY I. CARDIAC NERVE SUPPLY From the Vagus Nerves A. Extrinsic Nerve Supply Vagal cardiac nerve branches arise in the neck, descend into the B. Intrinsic Nerve Supply thorax, and join into the cardiac plexuses C. Conducting System of the Heart Postganglionic parasympathetic fibers terminate on the: D. Internodal Conduction Pathway 1. Sinoatrial and atrioventricular nodes II. ARTERIAL SUPPLY OF THE HEART 2. Coronary arteries A. Right Coronary Artery B. Left Coronary Artery NOTE: No termination on cardiac muscle, only the sympathetic C. Coronary Artery Dominance nerve supply III. VENOUS DRAINAGE OF THE HEART ACTION: (reverse of sympathetic nerve supply) IV. SURFACE ANATOMY OF THE HEART ○ (-) CHRONOTROPY A. Large Arteries of the Thorax Decreased heart rate B. Large Veins of the Thorax ○ (-) INOTROPY C. Lymph Nodes Decreased force of contraction ○ Constriction of the coronary arteries I. CARDIAC NERVE SUPPLY Even when we are asleep, the heart will still beat. The mind will not Extrinsic and intrinsic networks innervate the heart. command the heart to beat. In the sympathetic nerves there are Both sympathetic and parasympathetic fibers of the autonomic nervous afferent fibers that run through that area that does not reach our system form the extrinsic nerve supply. consciousness. That’s why each beating of the heart is not felt by The conducting system of the heart forms the intrinsic nerve tract. us. Not unless you have an MI. Myocardial Infarction A. EXTRINSIC NERVE SUPPLY ○ Decrease blood supply in the coronary arteries Afferent fibers running with the sympathetic nerves carry nervous impulse ○ The afferent fibers that are running through the Do not reach consciousness sympathetic nerve supply will reach our consciousness Decreased blood supply to the myocardium causes pain impulses to reach resulting in pain and it will reach cervical area, thoracic consciousness via this pathway area (jaw, left upper extremities or even back pain Afferent fibers running with the Vagus nerve take part in cardiovascular depending on what coronary artery is affected) reflexes ○ It may sometimes cause epigastric pain → one sign of o Baroreceptor reflex - blood pressure regulator myocardial infarction which involves the right coronary o Bainbridge reflex - increase in heart rate following an increase in artery → supplying the right ventricle which is located cardiac preload on the inferior aspect of the chest, sits on the central tendon resulting in epigastric pain. In a heart failure patient, when too much blood is going through the heart, the preload is venous return. When there’s too much blood going to the right side of the heart, the cardiac reflex, which is the Bainbridge reflex, will try to pump forcefully. If 1000 mL enters the heart, 1000 mL should exit the left ventricle by increasing the force of contraction and heart rate. a. SYMPATHETIC NERVE SUPPLY Upper thoracic spinal cord segments Routes through the cervical and upper thoracic sympathetic chain ganglia Descends through sympathetic cervical and thoracic cardiac nerves Enters the cardiac plexuses situated below the arch of aorta around the base of heart Post ganglionic sympathetic fibers terminate on the: 1. Sinoatrial and atrioventricular nodes 2. Cardiac muscle fibers 3. Coronary arteries Functions (activation will result in): 1. Cardiac acceleration 2. Increased force of contraction of the cardiac muscle 3. Dilatation of the coronary arteries If sympathetic nerve supply is activated: ○ (+) CHRONOTROPY Heart muscle will increase in heart rate ○ (+) INOTROPY Force of contraction of the heart will be increased and there will be pulmonary dilatation Figure 1. Nerve Supply of the Heart (Extrinsic and Intrinsic) Page 1 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado Figure 3. Cardiac Conduction System C. CONDUCTING SYSTEM OF THE HEART a. SINOATRIAL (SA) NODE Found in the wall of the right atrium (conduction is from the right to lower to posterior) Why is it important to know that normal conduction is from right to left and posterior? ○ Because in an ECG, any lead that is facing away, not facing the trajectory of the impulse, will have a negative deflection. Those in the lateral leads facing the conduction system will show a positive deflection. However, if there is myocardial infarction or disturbance of the conducting system, the ones that should give positive deflection normally will have negative deflection, indicating that there is something Figure 2. Sympathetic and Parasympathetic Nerves wrong with the conduction. Found between the junction of the crista terminalis and the superior vena cava B. INTRINSIC NERVE SUPPLY (Conducting System) Ability to contract spontaneously Spontaneously gives origin to rhythmic electrical impulses (Fastest giver of electric impulses) Independent of the extrinsic nervous system “PACEMAKER” of the heart Network of specialized cardiac muscle cells Approximately 80-100 bpm Generate rhythmic cardiac impulses Normal heart rate: 70 – 90 bpm (resting Derived from embryonic sinus venosus adult) Conduct and coordinate the intrinsic contractions of the myocardium b. ATRIOVENTRICULAR (AV) NODE o According to Bates, the normal heart rate is 60–100 bpm. But in cardiac patients, the normal heart rate is 50-60 bpm. We don’t Located at lower part of the atrial septum want to increase the oxygen demand of the patient by increasing Between the attachment of the septal cusp of the tricuspid valve the heart rate. We want very low heart rates in cardiac patients. and opening of coronary sinus We follow Bates normal heart rate Stimulated by the excitation wave as it passes through the atrial Function: myocardium ○ Act as a pacemaker depending on the lesion and the ability of each Speed of conduction about 0.11 sec node to perform well ○ Have a slight delay to allow ventricular filling If the SA node is not performing well, the AV node will Serves as the “TRAFFIC LIGHT” take place AV nodes delay the excitation of the ventricles because c. ATRIOVENTRICULAR (AV) BUNDLE the AV node will pierce the cardiac skeleton (the cardiac Only pathway of cardiac muscle that connects the myocardium of skeleton acts as an insulator that prevents the the atria and the myocardium of the ventricles —-> pierce the fibro conduction of impulses from the LA or RA to the skeleton of the heart ventricles simultaneously.) There’s a slight delay to Descends behind the septal cusp of the tricuspid valve and extends allow ventricular filling; the intrinsic nerve supply into the membranous part of the ventricular septum causes excitation across the ventricles. Page 2 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado Upper border of the muscular part of the septum it divides into two A patient will have decompensated heart failure leading to death branches: If there is massive myocardial infarction, it affects all the ○ Right Bundle Branch (RBB) conducting system except Purkinje Fiber which is left to contract Right side of IVS (Interventricular Septum) → the ventricles, so the heart rate would be around 20-30 bpm. The moderator band (bridge) → anterior wall (until it heart would eventually fail because it will not be able to sustain the becomes Purkinje Fiber) cardiac output that is sufficient enough to cause dispersion of ○ Left Bundle Branch (LBB) oxygen throughout the body. ECG would show low heart rate, Left of IVS (Interventricular Septum) → anterior and meaning that the conducting system of the body which is the upper posterior part SA NODE, AV NODE is greatly affected. Supplies the anterior and posterior part of your ventricles Modulator band has a very good function in the right side going down directly to the heart muscles. It will go to the modulator band and still connect from the septum directly to the apical side but the rest will connect to the anterior surface of the right ventricle through the modulator band. As the bundle branch goes toward the wall of the ventricles, it will pierce the Subendocardial branches becoming the Terminal conducting fibers which are your Purkinje fibers. Figure 5. Conducting system of the Heart D. INTERNODAL CONDUCTION PATHWAYS Conduction pathway found in right atrium, responsible for innervating path for the right atrium Impulses from the SA node travel to AV node faster than they can travel along the myocardium Attributed to the internodal pathways that are consisting of Purkinje fibers and ordinary cardiac muscle a. Anterior Internodal Pathway leaves the anterior end of SA node and passes anterior to the superior vena caval opening, descends on the atrial septum and ends in the AV node b. Middle Internodal Pathway leaves the posterior end of the SA node and passes posterior to the superior vena caval opening, descends on the atrial septum and ends in the AV node c. Posterior Internodal Pathway leaves posterior part of SA node and descend through the crista Figure 4. Sinoatrial and Atrioventricular Node terminalis and the valve of the inferior vena cava d. SUBENDOCARDIAL BRANCHES (Terminal Conducting Fibers, Purkinje Fibers) The terminal branches of conducting system ramify throughout the ventricular myocardium in a plexiform fashion Have the highest conduction velocity (4 to 5 m/s) in the heart No. of beats per min produce by terminal branches of heart will be a little bit lower than the sinoatrial node Sinoatrial nodes fire up to 60-100 beats/min while Purkinje beats around 20-30 beats/min If SA node malfunctions, AV node takeover, thus heart rate is slower If a patient has coronary disease (specially right coronary disease) there will be slowing of conduction. Purkinje will take over as pacemaker, heart beat at around 30-40 not effective in pumping of the ventricle. Page 3 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado Figure 6. Internodal Conduction Pathway ○ Continues posteriorly along with AV groove to anastomose II. ARTERIAL SUPPLY OF THE HEART with left coronary artery in the posterior interventricular o The coronary arteries are attached to your aorta. The aortic cusps will give off groove your left and right coronary arteries; the right main coronary artery is given off The right coronary artery passes through the atrioventricular by the right coronary cusps (cc), and left coronary artery by the left coronary groove and encircles until it goes to the posterior portion of the cusps heart. From the posterior level, the RCA will anastomose with the Right Coronary Artery (RCA)– binds over and passes through the right LCA atrioventricular groove RCA goes backward until it becomes a posterior descending branch Left Coronary Artery (LCA) – divide into circumflex branches, passes through The dominant coronary artery will supply blood in the posterior left atrioventricular groove. Another part (anterior interventricular branch) will portion of the heart descend into the anterior interventricular groove BRANCHES OF THE RIGHT CORONARY ARTERY Atrial branch ○ Supply the anterior and lateral surfaces of the right atrium ○ Posterior wall of left and right atria ○ Supplies SA node ○ Sinoatrial node artery - 35% arises from LCA Right Conus Artery ○ Pulmonary conus and upper part arterial wall of RV ○ Gross anatomically, it supplies the infundibulum ○ First branch Anterior ventricular branches ○ Anterior surface of RV ○ Marginal Artery Lowest part Posterior ventricular branches ○ Diaphragmatic surface of the heart Posterior Interventricular (Descending) Artery ○ Posterior part of the ventricular septum but not to the apical part ○ Supplies AV node (90%) ○ It may originate from circumflex branch Figure 7. Major Coronary Artery (Blood Vessels) A. RIGHT CORONARY ARTERY (RCA) Supplies most of the right atrium Most of the right ventricle Left ventricle (diaphragmatic surface) Posterior 3rd of the Ventricular septum 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 decreased 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 Figure 8. Branches of the Right Coronary Artery ○ Run to the right side between the pulmonary trunk and right auricle ○ Descends vertically in the right AV groove ○ Inferior border of the heart Page 4 of 10  [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado B. LEFT CORONARY ARTERY (LCA) 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 Left aortic sinus -> between the pulmonary trunk and left auricle Atrioventricular groove and divides into anterior interventricular branch and a circumflex branch BRANCHES OF THE LEFT CORONARY ARTERY 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 In patients with myocardial infarction, that has a left coronary dominance, and there is a blockage of the diagonal arteries, it can also cause deterioration of the Figure 9. Branches of the Left Coronary Artery heart because the anterior aspect of the ventricles will not pump efficiently. C. CORONARY ARTERY DOMINANCE If the non-dominant heart is blocked, the dominant Refers to the variable origin of the posterior interventricular artery heart still has blood supply coming from the other side ○ Right dominance of the coronary arteries. Posterior interventricular artery is a large branch of the ○ A small left conus artery supplies the pulmonary conus right coronary artery Circumflex artery Present in most individuals (67%) ○ Same size as the anterior interventricular artery ○ Left dominance ○ Winds around the left margin of the heart in the atrioventricular Posterior interventricular artery is a branch of the groove circumflex branch of the left coronary artery (15%) ○ Left marginal artery is a large branch that supplies the left margin ○ Codominance of the left ventricle down to the apex Both the right coronary and circumflex arteries (18%) Anterior ventricular and the Posterior ventricular branches Contribute to the formation of the posterior ○ Supply the left ventricle interventricular artery or to multiple branches that Atrial branches substitute for that vessel ○ Supply the left atrium When you do a coronary angiogram, it will also tell you the dominance of the Sinoatrial node heart. For example, in the left anterior descending blockage, which is not a ○ Predominantly supplied by the right but sometimes by the left non-dominant heart, but a right dominant heart, you will see that the patient coronary artery will not die immediately because there are branches. Take note that if there is Atrioventricular node an MI, it will result in ischemia, and ischemia will cause the heart to regenerate ○ Mostly supplied by right coronary artery new vessels over time. Atrioventricular bundle If a patient has frequent episodes of increased oxygen level, the heart will form ○ Right coronary artery new blood vessels that would connect other blood. For example, if the LA was RBB (Right Bundle Branch) blocked, it would create new vessels there, and then it will supply that area, so it means that the heart is supplied by new vessels, but not yet very active ○ Left coronary artery on its function, because it is still new vessels, but overtime if these vessels will LBB (Left Bundle Branch) grow in size, these new vessels will also be helpful in the supply of the coronary ○ Right and left coronary arteries arteries of the cardiac vessels. ○ Anterior Branch Most likely supplied by the left anterior descending artery ○ Posterior Branch Right coronary artery Page 5 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado Table 1. Major Coronary Veins and accompanying Coronary Arteries CORONARY ARTERY INFARCT LOCATION ECG SIGNATURE More distal LAD Antero apical ST elevation: V2 to 4 Inferior wall if wrap ST elevation: I, III, F Figure 10. Origin and Distribution of the Posterior Interventricular Artery in the Right and around LAD Left dominance Distal LAD Anteroseptal ST elevation: V1 to 3 Early obtuse, marginal High lateral wall ST elevation: I, L, V4 to 6 More distal marginal Small lateral wall ST elevation: I, L, or V4 to branch, circumflex 6 or no abnormality Circumflex Posterolateral ST elevation: V4 to 6; ST depression: V1 to 2 Distal RCA Small inferior wall ST elevation: II, III, F; ST depression: I, L Proximal RCA Large inferior wall and ST elevation: II, III, F; ST posterior wall depression: I, L, V1 to 3 Some lateral wall ST elevation: V5 to 6 RCA Right ventricular ST elevation: V2R to V4R; Figure 11. Codominance Usually, inferior some ST elevation: V1; or ST elevation: II, III, F Table 2. Coronary Artery Lesions, Infarct Locations, and ECG Signatures III. VENOUS DRAINAGE OF THE HEART Majority of all venous drainage or veins of the heart will land immediately to the right atrium Based on the coronary artery affected, you will know which part of the heart will be involved, then you will know the leads that will be Middle cardiac vein, great cardiac vein and small cardiac vein will land in the presented in the given ECG coronary sinus except the anterior cardiac vein, because the anterior cardiac vein will directly drain into the right atrium V6 is in the lateral side, so the chamber is the left ventricle, if you have an MI in Q wave (V1-V6) the left ventricle is affected V1-V6 impulses are right to the left (anything going to V6 should have a positive R wave) as compared to V1 and V2 going away from the impulse of the conduction system which have small R wave V1-V6 — increasing in size V3-V4 — should have an upright R wave ST segment is still isoelectric ST elevation will have MI in the RV wave Figure 12. Coronary Artery Anastomoses Page 6 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado IV. SURFACE ANATOMY OF THE HEART A. LARGE ARTERIES OF THE THORAX Location of the heart valve anatomically Auscultally location of the heart valves 1. AORTA Ascending ○ Right Coronary Artery and Left Coronary Artery Aortic arch ○ Brachiocephalic artery – 1st branch ○ Right subclavian artery – supplies the right upper arm ○ Right common carotid artery – supplies the brain ○ Left common carotid artery — 2nd branch, gives rise to internal and external carotid artery ○ Left subclavian artery — 3rd branch, supplies the right upper arm ○ The left subclavian and left common carotid will be attached or branched out from the aorta whereas the right one will be branching out from the brachiocephalic. So, from here if we go up from the common carotid, we have the internal carotid artery and external carotid artery then it goes to the brain. Then after this left subclavian artery that is now your descending artery. So, after your subclavian is your descending artery. The descending aorta and the arch of aorta are critical during an aneurysm. So, anything that is beyond 5.5 cm means that the patient is at risk of aortic rupture. Normal size of the aorta is 3 cm. Descending thoracic aorta ○ Posterior intercostal artery ○ Subcostal artery - widening at the lower border of the 12th rib and pierces the central tendon becoming the abdominal aorta or Figure 12. Four valves of the Heart branches from abdominal aorta a. Tricuspid Valve ○ Pericardial, esophageal, bronchial arteries lies behind the right half of the sternum opposite the 4th intercostal space Abdominal aorta b. Mitral Valve ○ Celiac branch, mesenteric and right and left renal branches, behind the left half of the sternum opposite the 4th costal ovarian and testicular artery, mesenteric (inferior) to major cartilage arteries to become the internal iliac which supplies the suprapubic c. Pulmonary Valve area then external iliac which will go down to femoral artery which behind the medial end of the third left costal cartilage and is responsible for the supply in the lower extremity adjoining part of sternum d. Aortic Valve 2. PULMONARY TRUNK behind the left half of the sternum opposite the 3rd ○ Left and right pulmonary artery, ligamentum arteriosum > intercostal space abdominal aorta ○ Comes from the right atrium that will give off non oxygenated Mitral/bicuspid and tricuspid are called Atrioventricular (AV) valves blood. Pulmonary vein gives off oxygenated blood that comes from the pulmonary circulation and the pulmonary artery will go Pulmonary and Aortic are called Semilunar(SL) valves to the circulation for oxygenation. The pulmonary trunk Pulmonic valve - located on the right but during auscultation will be on the embryonically also has a connection to your aorta which is called left ductus arteriosus. When the baby is born the ductus arteriosus will Aortic valve - located on left but during auscultation will be on the right have a spasm, it will cause that to close and it will become your ligamentum arteriosum. So, from your descending artery we have your abdominal aorta. Table 3. Comparison of anatomical location and auscultation areas of cardiac valves Page 7 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado Figure 13. Anterior view of the Thoracic aorta Figure 15. Anterior view of the Abdominal aorta B. LARGE VEINS OF THE THORAX They receive blood drainage from the head, neck, upper limbs, and thorax. The inferior vena cava receives blood mainly from the body below the diaphragm and has only a brief appearance in the thorax. 1. Pulmonary Trunk 2. Brachiocephalic Veins o Receive blood coming from the superior vena cava a. The right and left brachiocephalic veins form at the root of the neck on each side by the union of the respective and internal jugular veins. b. The left brachiocephalic vein passes obliquely downward and to the right behind the manubrium sterni and in front of the large branches of the aortic arch. The right brachiocephalic vein is relatively short and descends almost vertically. The two brachiocephalic veins join to form the superior vena cava. o The two (right and left) brachiocephalic veins fuse to form the superior vena cava 3. Superior Vena Cava (SVC) ○ From the fusion of your brachiocephalic vein. (The vein has two brachiocephalic while the artery has only one brachiocephalic.) ○ 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. ○ Brachiocephalic vein- forms the superior vena cava. 4. Azygos Veins ○ Enters SVC (Superior vena cava) ○ Drain the posterior circulation in the thorax, pericardium and others Figure 14. Anterior view of the Abdominal aorta ○ Consists of: ○ 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 the level of the 5th thoracic vertebra. Here, it arches forward above the root of the right lung to empty into the posterior surface of the superior vena cava. Page 8 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado Drains: posterior parts of the intercostal spaces, the posterior abdominal wall, the pericardium, the c. Internal thoracic nodes diaphragm, the bronchi and the esophagus drain the deep lymph vessels of the anterior parts of the Named after the organ that it will drain intercostal space. From here, the lymph enters the thoracic duct. o Inferior Hemiazygos Vein Thoracic wall nodes drain in the bronchomediastinal trunk ○ Formed by the union of the left ascending lumbar while posterior intercostal nodes will drain into the thoracic vein and the left subcostal vein in the abdomen trunk. Two major drainage systems: (often forms the inferior hemiazygos vein. It o Bronchiomediastinal ascends through the left crus of the diaphragm and, o Posterior intercostal node at about the level of the eighth thoracic vertebra, d. Posterior intercostal node turns to the right and joins the azygos vein. It o drains into the thoracic trunk receives as tributaries some lower left intercostal veins and mediastinal veins.) THORACIC DUCT ○ Coming from below it will drain it into the inferior area. ○ Begins below in the abdomen as a dilated sac, the cisterna chyli o Superior Hemiazygos Vein ○ gradually crosses the median plane behind the esophagus and ○ Formed by the union of the left superior intercostal reaches the left border of the esophagus (T4 level) vein and the fourth to the eighth intercostal veins ○ Here, it bends laterally behind the carotid sheath and in front of ○ It joins the azygos vein at the level of the seventh the vertebral vessels thoracic vertebra. ○ All of the drainage in the left and what’s below half of the body 5. Inferior Vena Cava (IVC) will be drained into the cisterna chyli and then drained into the ○ Responsible for venous drainage for almost all the blood coming right atrium from the lower extremities of the body and in the abdomen ○ It turns downward in front of the left phrenic nerve and crosses ○ Pierces the central tendon of the diaphragm opposite the eighth the subclavian artery to enter the beginning of the thoracic vertebra and almost immediately enters the lowest part brachiocephalic vein of the right atrium ○ Lymphatics is the 3rd circulatory system of the body, and it drains excess fluid in our body. Once the lymph nodes are blocked this will cause edema and swelling of those areas being drained. So, all structures coming from the right side of the body, the upper extremities, and right side of the face, will be drained by the right lymphatic duct and anything beyond, the left and lower extremities will be drained into the thoracic duct until it goes to the bronchomediastinal trunk and lead to either superior or inferior vena cava. So, all of them will be drained into the IVC, SVC, and to the right atrium. ○ Causes blockage of the lymphatics: tumor (external compression of your lymphatics), infection, elephantiasis, plaque formation that will also obstruct the body. ○ Anything on the right side will be drained by the right lymphatic duct and thoracic duct on the left side Figure 16. A. Major veins entering the Heart B. Major veins draining the Superior and Inferior Vena Cava C. LYMPH NODES The lymph vessels in the thorax collect lymph from virtually all parts of the body below the neck and upper limbs. Further, the upper ends of these vessels (located in the root of the neck) typically collect the drainage from the head, neck, and upper limbs THORACIC WALL ○ Thoracic wall nodes drain in the bronchomediastinal trunk while posterior intercostal node will drain into the thoracic trunk ○ Has several lymph nodes that drains excess fluid of our body a. Anterior axillary nodes o drain the lymph vessels of the skin of the anterior thoracic wall b. Posterior axillary nodes o drain the lymph vessels of the skin of the posterior thoracic wall Page 9 of 10 [ANATOMY] 1.07 CARDIAC NERVE SUPPLY, ARTERIAL SUPPLY, VENOUS DRAINAGE, AND SURFACE ANATOMY- Dr. Leslie Asuncion- Viado 6. Predominantly supplied by the right but sometimes by the left coronary artery a. Atrioventricular node b. Atrioventricular bundle c. Sinoatrial node d. Right Bundle Branch 7. This artery is the 1st branch of the aortic arch. a. Brachiocephalic artery b. Right subclavian artery c. Left subclavian artery d. Left common carotid artery 8. The right coronary artery supplies the following, EXCEPT: a. Sinoatrial node b. Atrioventricular node c. Atrioventricular bundle d. Right bundle branch 9. The following are terminal point of the post-ganglionic sympathetic fibers of the extrinsic nerve supply, EXCEPT: a. SA nodes b. Cardiac muscle fibers c. Coronary arteries d. None of the above 10. It is responsible for venous drainage of the blood coming from the lower extremities of the body and in the abdomen Figure 16. Distribution of Lymphatic vessels and Lymph nodes a. Superior vena cava b. Inferior vena cava V. REFERENCES c. Superior hemiazygos vein Netter's Atlas of Human Anatomy 7th edition d. Inferior hemiazygos vein Snell’s Clinical Anatomy by Regions 9th Edition ANSWERS VI. TEST YOURSELF 10. B 1. What is the normal heart rate of a resting adult? 9. D 2. An internodal pathway that leaves the posterior end of the SA node and passes posterior to the superior vena caval opening. 8. D 7. A 3. A cardiovascular reflex that regulates blood pressure. 6. C 4. It is the same size as the anterior interventricular artery. It winds around the left margin of the heart in the AV groove 5. A 4. B a. Anterior Interventricular (descending) branch b. Circumflex Artery 3. Baroreceptor reflex c. Anterior Ventricular and posterior ventricular branches d. Atrial branches 2. Middle internodal pathway 1. 70-90 bpm 5. Type of dominance that is present in most individuals (67%). Posterior interventricular artery is a large branch of the right coronary artery. a. Right dominance b. Left dominance c. Codominance Page 10 of 10