Anatomy Module 7 Study Guide PDF

Module 7 Study Guide Pericardium & Heart Pericardium Fibroserous membrane that covers the heart & beginning of its great vessels Pericardium layers: o Fibrous Pericardium → outermost fibrous layer (Inelastic) ▪ Attaches inferiorly and anteriorly to the s...

Module 7 Study Guide Pericardium & Heart Pericardium Fibroserous membrane that covers the heart & beginning of its great vessels Pericardium layers: o Fibrous Pericardium → outermost fibrous layer (Inelastic) ▪ Attaches inferiorly and anteriorly to the sternum and diaphragm ▪ Blends with adventitia of great vessels as the enter or leave the sac ▪ Holds heart in middle mediastinal position ▪ Limits expansion of heart o Serous Pericardium → inner serous layer ▪ Lubricated surface allows heart free movement required for motions during contraction ▪ Divides into: Parietal Layer of Serous Pericardium → lines inside of cavity (dense fibrous layer, areolar tissue, mesothelium) Visceral Layer (epicardium) of Serous Pericardium → covers over heart Pericardial Cavity of Serous Pericardium → between parietal and visceral layers with pericardial fluid Heart Wall (wall of heart chamber) o Epicardium (visceral layer of serous pericardium) → outer visceral layer ▪ Thin external layer (mesothelium and areolar tissue) formed by visceral layer of serous pericardium ▪ Prevents blood from clotting o Myocardium ▪ A thick, helical middle layer ▪ Composed of cardiac muscle and connective tissues ▪ Contracting o Endocardium → innermost layer ▪ Thin internal layer of endothelium, subendothelial connective tissue and areolar tissue ▪ Lines inside of heart chamber and covers its valves ▪ Has a slippery lining to help with movement Arterial Supply, Venous Drainage & Nerve Supply of Pericardium Arteries: Supply from the pericardiacphrenic artery (branch of internal thoracic artery) Veins: Drainage from pericardiacphrenic veins (tributaries of brachiocephalic veins) Neve Supply: supply from phrenic nerves (C3-C5) o Referred pain (Pain of internal organs felt in other areas) sensations conveyed by these nerves → commonly felt on top of the shoulder of the same side Pericardiocentesis Cardiac Tamponade: excess pericardial fluid or bleeding inside pericardium that can compromise pumping function o To remove excess fluid → wide-bore needle inserts through the left 5th or 6th intercostal space ▪ This is near the sternum through the bare area of the pericardium  o Could also remove fluid from xiphocondral angle but must be careful about puncher of internal thoracic arteries Heart A double, self-adjusting suction and pressure pump Pump works together to receive blood from veins and pump it to arteries 2 Phases: o Relaxation (diastole) o Contraction (systole) Right side of heart (right heart) receives poorly oxygenated blood o Received deoxygenated blood from the body through superior and inferior vena cava o Gets pumped through pulmonary trunk and arteries to the lungs for oxygenation in pulmonary circulation Left side of heart (left heart) receives oxygenated blood o Receives oxygenated blood from the lungs through pulmonary veins o Pumps oxygenated blood into the aorta for distribution systemic circulation to the body **What happens when there is a connection of oxygenated and deoxygenated blood in the lungs?** A natural shunt is created (an abnormal pathway in the body where blood or fluid naturally flows from one area to another without following the normal route) Chambers of Heart (has 4) Right & left side separated by interventricular and interatrial septum 2 Artia (L & R) o Superior chambers that receive blood from major veins 2 Ventricles (L & R) o Inferior discharging chambers that pump the blood into major arteries (more muscular) **Atria is not essential for fxn of heart. It assists ventricles. If atria are not working, heart could still fxn. But, if ventricles are not functioning the heart will stop working.** Interior of Right Atrium Sinus venarum → smooth thin-walled, posterior part Pectinate muscles → rough, muscular anterior wall Sulcus terminalis → smooth and rough parts of atrial wall are separated by: o Externally: sulcus terminalis or terminal groove o Internally: vertical ridge, the crista terminalis or terminal crest  The opening of the coronary sinus and oval fossa is found in right atrium Interatrial septum → a muscular wall that separates the right and left atria of the heart Interior of Left Atrium Larger smooth-walled part Smaller muscular auricle containing two pectinate muscles 4 pulmonary veins (two superior and two inferior) → enters smooth posterior wall Slightly thicker wall than the right atrium Interatrial septum that slopes posteriorly and to the right Right Ventricle Receives blood from right atrium Pumps blood into pulmonary trunk Internal walls of right ventricle: o Trabeculae carneae → muscular ridges o Papillary muscles → muscular flinger like projections o Chordae tendineae → fine strings that attach the papillary muscles to leaflets of tricuspid valves Left Ventricle Forms apex of heart Three times thicker than right ventricle → exerts more pumping force Internal walls of left ventricle: o Trabeculae carneae o Papillary muscles o Chordae tendineae Pumps blood into aorta The Heart Valves Two pair of one-way valves prevent backflow during contraction Atrioventricular (AV) valves: o Right AV valve (tricuspid valve) → between right atrium and right ventricle o Left AV valve (bicuspid or mitral valve) → between the left atrium and left ventricle Semilunar valves with three susps support like tripod o Prevents backflow from pulmonary trunk and aorta into ventricles o Right semilunar (pulmonary) valve → between right ventricle and pulmonary trunk o Left semilunar (aortic) valve → between left ventricle and aorta Fibrous Skeleton of Heart Isolated fibrous skeleton is composed of four fibrous rings (or two rings and two “coronets”) o Each fibrous ring encircles: ▪ a valve, ▪ two trigones between valves ▪ membranous portions of the interatrial, interventricular, and atrioventricular septa.  Keeps the orifices of the AV and semilunar valves patent Provides attachments fir he leaflets and susps of valves Provides attachment for myocardium Forms electrical “insulator” by separating: o Myenterically conducted impulses of atria o Ventricles so that they contract independently Heart Sounds (Lub-dup) Sounds of valves closing First sound: “Lub” o The AV valves closing Second sound: “dup” o The semilunar valves closing Faulty valve function can cause abnormal heart sound called murmur Vasculature of Heart Artery/Branch Origin Right coronary Artery (RCA) Right aortic sinus SA nodal RCA near its origin (in 60%) Right marginal RCA Posterior Interventricular RCA (in 67%) AV nodal RCA near origin of posterior IV artery Left Coronary Artery (LCA) Left aortic sinus SA nodal Circumflex branch of LCA (in 40%) Anterior interventricular LCA Circumflex LCA Left marginal Circumflex branch of LCA Posterior interventricular LCA (in 33%) Venous Drainage of Heart Cardiac veins collect blood from capillary beds o Great cardiac vein → runs in anterior interventricular sulcus o Middle cardiac vein → in posterior interventricular sulcus o Small cardiac vein → from inferior margin Coronary sinus → formed by merging cardiac veins that empty into right atrium The left posterior ventricular vein and left marginal vein also open into the coronary sinus Coronary Artery Disease (CAD) #1 cause of death in developed countries Atherosclerosis—fatty deposits Ischemia—low blood supply leads to hypoxia Angina pectoris—chest pain from heart Myocardial infarction (MI)—Heart attack, tissue death (necrosis) because of blocked coronary artery by a blood clot Conducting System A series of specialized cardiac muscle cells that generate and conduct electric impulse (depolarization) for myocardial contraction  After each depolarization comes repolarization which causes relaxation of heart muscles Heart is independent from the brain for heartbeats Purkinje fibers (subendocardial conducting network) → specialized cardiac muscle cells that play a crucial role in the electrical conduction system of the heart. Electro Cardiography (ECG) Consists of waves, intervals and segments o P wave: Represents depolarization of the atria o QRS complex: Represents ventricular depolarization o T wave: Represents ventricular repolarization Cardiac Nerves & Plexus Heart rate is altered by brain controls Parasympathetic fibers – decreases the heart rate Sympathetic fibers – increases the heart rate and strength of contraction Controlled by cardiac centers in medulla Microscopic Anatomy of Cardiac Muscle Cardiac Muscle Cell: Straited Branching Has one or two nuclei Cells join at intercalated discs Involuntary function Clinical Conditions Atrial Septal Defect (ASD) o A hole in the heart wall that separates the upper chambers of the heart, called the atria o The hole increases the amount of blood going through the lungs o It's a congenital heart defect, meaning it's present at birth Ventricular Septal Defect (VSD) o a congenital heart defect that occurs when there's an abnormal hole in the wall that separates the heart's two lower chambers, or ventricles o If the hole is large, too much blood will be pumped to the lungs. This can lead to heart failure. Dextrocardia o The heart is positioned on the right side of the chest instead of its normal position on the left side. o Dextrocardia on its own does not usually cause problems, but it tends to occur with other conditions that can have serious effects on the heart, lungs and other vital organs. Mediastinum The central compartment of the thoracic cavity o Between the two pulmonary cavities Contains all the thoracic viscera and structures except lungs Mediastinum is divided into superior and inferior mediastinum parts o Divided by the transverse thoracic plane → a horizontal plane that includes the sternal angle o Passes through the IV disc of T4 and T5 vertebrae posteriorly Inferior mediastinum → between transverse thoracic plane and diaphragm o Further subdivided by pericardium into: ▪ Anterior mediastinum ▪ Middle mediastinum - The pericardium and its contents (heart and roots of its great vessels) ▪ Posterior mediastinum Superior Mediastinum The major structure in the superior mediastinum (from anterior to posterior): 1. Thymus 2. Veins 3. Arteries 4. Airway 5. Alimentary tract 6. Lymphatic trunks Aorta and its Branches in Thorax Arch of aorta Continuation of ascending aorta  Arches posteriorly on left side of trachea and esophagus and superior to left main bronchus. Branches: o Brachiocephalic o left common carotid o left subclavian Anterior Mediastinum The smallest subdivision of the mediastinum Between sternum and transverse thoracis muscles Significant primarily as a surgical plane Contains primarily loose connective tissue In infants & children → inferior extend of thymus Posterior Mediastinum Located inferior to transverse thoracic plane o Anterior to T5-T12 o Posterior to pericardium and diaphragm o Between parietal pleura of two lungs The posterior mediastinum contains: o thoracic aorta o thoracic duct and lymphatic trunks o posterior mediastinal lymph nodes o azygos and hemi-azygos veins o esophagus and esophageal nerve plexus Aorta and its Branches in Thorax Thoracic (descending aorta) major branches: o Posterior intercostal o Bronchial (1-2 branches) o Esophageal (4-5 branches) o Superior phrenic (varies in number) The Azygos System of Veins Azygos vein forms a collateral pathway between the SVC and IVC o Drains blood from posterior wall of thorax and abdomen o It arches over the superior aspect of the root of the right lung to join the SVC Hemi-azygous vein arises on the left side by the junction of the left subcostal and ascending lumbar veins o Ascends on the left side of the vertebral column where it crosses to join the azygos vein Trachea Trachea descends anterior to the esophagus and enters the superior mediastinum o Including a little to the right of the median plane Posterior surface of trachea is flat where it is applied to the esophagus Trachea ends at the level of the sternal angle by dividing into right and left main bronchi o Terminates superior to the level of the heart and is not a component of the posterior mediastinum Esophagus A fibromuscular tube that extends from the pharynx to the stomach Between the trachea and vertebral column Inclines to the left but pushed back to median plane by arch of aorta Esophagus is compress by three structures: o Aorta arch o Left main bronchus o Diaphragm Inferior to the arch, esophagus inclines to the left as it passes through the esophageal hiatus in diaphragm Nerves of Thorax **Plexus = mix of parasympathetic and sympathetic nerves (autonomic → smooth muscle, involuntary)** Vagus (cranial nerve X) Esophageal Plexus → right and left vagus nerves (parasympathetic) and splanchnic nerves from sympathetic trunk Recurrent laryngeal → vagus nerve The sympathetic trunks and their associated ganglia form a major portion of the autonomic nervous system. o The thoracic trunks lie against the costovertebral joints and the sides of the vertebral bodies in the thorax. Cardiac plexus – made up from sympathetic and parasympathetic fibers (involuntary) Pulmonary plexus - made up from sympathetic and parasympathetic fibers (involuntary) Phrenic – somatic, supplies diaphragm Intercostals - Anterior rami of T1–T11 nerves Subcostal - Anterior ramus of T12 nerve  Parasympathetic comes from vagus nerves (cranial nerves) Sympathetic comes from sympathetic trunk (located on two side of vertebral column) that makes splanchnic nerves Thoracic Ducts and Lymphatic Trunks In posterior mediastinum → thoracic duct lies on anterior aspect of the bodies of the inferior 7 vertebrae Thoracic duct originated from cisternal chyli (chyle cistern) in the abdomen Thoracic duct ascends through the aortic hiatus in the diaphragm Ascends in posterior mediastinum among: o the thoracic aorta on its left, o the azygos vein on its right o esophagus anteriorly o vertebral bodies posteriorly At the level of T4, T5 or T6 vertebra, thoracic duct crosses to the left, posterior to esophagus and ascend into superior mediastinum Lymph Nodes of Posterior Mediastinum Posterior mediastinal lymph nodes lie posterior to pericardium o Related to the esophagus and thoracic aorta There are several nodes posterior to part of esophagus and up to eight anterior and lateral to it Lymph from the nodes drains to right or left venous angles via the right lymphatic duct or thoracic duct