9.15.11+-+SS+Mediastinum+and+Heart

OBJECTIVES:

=1. Define the boundaries and contents of each division of the mediastinum:=

=2. Identify the following vessels and structures of the thoracic region and contents of the middle mediastinum:=
 * Division || Boundaries || Contents ||
 * Superior mediastinum || Superior Border: the superior thoracic aperture. Inferior Border: the transverse thoracic plane formed by the sternal angle anteriorly and the IV disc of T4-T5 posteriorly. It seems the mediastinal part of the parietal pleura defines the left and right borders. || Aortic arch, esopagus, trachea, superior vena cava, brachiocephalic trunk, left common carotid artery, left, subclavian artery, vagus nerve, phrenic nerve, pericardiophrenic artery and vein, the thymus. ||
 * Inferior mediastinum || Superior Border: the transverse thoracic plane formed by the sternal angle anteriorly and the IV disc of T4-T5 posteriorly. Inferior Border: the diaphragm. It seems that the parietal pleura defines the left and right borders. || Pericardium and its contents, all 8 of the great vessels, the esophagus, the phrenic nerve and pericardiacophrenic artery and vein ||
 * Anterior mediastinum (anterior division of inferior mediastinum) || Superior Border: the transverse thoracic plane. Inferior Border: the diaphragm. Posterior Border: the anterior surface of the pericardium. Anterior Border: the dorsal surface of the sternum and ribs 2-5. || Not much...the sternopericardial ligaments? ||
 * Middle mediastinum (middle division of inferior mediastinum) || The pericardium || The pericardium, heart, and roots of its great vessels--ascending aorta, pulmonary trunk, and SVC ||
 * Posterior mediastinum (division of inferior mediastinum) || Sup: the transverse thoracic plane. Inf: the diaphragm. Post: Bodies of vertebrae T5-T9. Ant: the posterior surface of the pericardium. || Esophagus, descending aorta, azygos vein ||


 * Fibrous Pericardium || The fibrous pericardium is the thick outer membrane surrounding the heart (deep surface: parietal pericardium; superficial surface: parietal pleura ||
 * Transverse pericardial sinus || The space posterior to the great vessels entering the base of the heart. Superior vena cave is dorsal to sinus. ||
 * Oblique pericardial sinus || The space dorsal to the heart; it is open at the apex of the heart and its superficial borders are formed by the trunks of the great vessels of the heart ||
 * Superior vena cava || Enters right atrium superiorly; formed by left and right brachiocephalic veins ||
 * Ascending aorta || Arterial vessel exiting superiorly from left ventricle; branch point for coronary arteries ||
 * Pulmonary trunk || Arterial vessel exiting superiorly from right ventricle (ventral to ascending aorta); branches to pulmonary arteries to lungs; carries deoxygenated blood ||
 * Inferior vena cava || Enters right atrium inferiorly; terminates 1 inch or so superior to diaphragm ||
 * Aortic arch || Location where ascending aorta turns dorsally and runs inferiorly ventral to vertebral column; branch point for brachiocephalic artery, left common carotid artery, and left subclavian artery ||
 * Ligamentum arteriosum || Ligament attaching pulmonary trunk to ascending aorta; remnant of prenatal shunt ||
 * Descending aorta || Principal artery to lower limbs and abdomen; runs ventral to vertebral column ||
 * Right atrium || Entrance point for all deoxygenated blood into heart. Entrances: superior vena cava, inferior vena cava, coronary sinus. Exit: tricuspid valve. ||
 * Auricle of right atrium || Outpocketing of right atrium ||
 * Right ventricle || Inferior, anterior chamber of heart; receives blood from right atrium through tricuspid valve; sends blood through pulmonary trunk to lungs ||
 * Left atrium || Entrance point for all oxygenated blood from lungs via pulmonary veins. Sends blood through mitral/bicuspid valve to left ventricle ||
 * Auricle of left atrium || Outpocketing of left atrium ||
 * Left ventricle || Largest chamber of heart; forms apex of heart, posterior and inferior portion of heart. Receives blood from left atrium via mitral valve; sends blood to body through aorta ||
 * Diaphragmatic surface of right border of heart || Posterior, inferior surface of heart; formed by right ventricle ||
 * Left border of heart apex || Formed by left ventricle ||
 * Pulmonary aa. and vv. || Pulmonary aa. originate at termination of pulmonary trunk, continue to lungs. Pulmonary vv. (normally 4) enter left atrium from lungs carrying oxygenated blood ||

=3. Describe the arterial supply, venous drainage and innervation of the pericardium.=

The arterial supply, venous drainage and innervation of then pericardium run together most commonly down the left and right sides of the pericardium through the fibrous pericardium. The arterial supply is primarily the pericardiacophrenic artery, but some blood may come from branches from the internal thoracic artery or the coronary arteries. The venous drainage is primarily the pericardiacophrenic vein, but some variable tributaries of the azygos venous system may contribute. The sensory portion of the innervation of the pericardium is from the phrenic nerves (so pain frequently gets referred to the C3-C5 dermatomes). The efferent portion of the innervation stems from the sympathetic trunks. The vagus nerves also connect, but function is uncertain.

=4. Name the four chambers of the heart.=

Right Atrium, Right Ventricle, Left Atrium, Left Ventricle =5. Identify the three layers of the heart wall.=

Endocardium, myocardium, epicardium (visceral pericardium layer of serous pericardium) =6. Review and define the following regions of heart:= All surfaces of the heart fall into one of the first five rows. The base and apex don't specifically lay flat against any other specific organ/tissue so they aren't assigned such clear labels. 5 surface areas 4 borders
 * Base || The posterior, superior portion of the heart formed by the left atrium and some right atrium and all of the vessels coming in and out of them ||
 * Apex || The inferior, anterior, left peak of the heart formed by the left ventricle ||
 * Sternocostal surface || The surface of the heart facing the sternum and the ribs. Formed by the right ventricle. ||
 * Diaphragmatic surface || The surface of the heart facing the diaphragm. Formed by the left ventricle mostly, with a little right ventricle thrown in there around the front. ||
 * Pulmonary surface || The surface of the heart facing the lungs. In our book separated into right and left pulmonary surfaces, formed by the surfaces of the right atrium and the superior left ventricle. ||
 * Right border || Formed by the right atrium and the ventral line of the superior and inferior vena cava (convex) ||
 * Left border || Formed by the left ventricle and partially the left auricle of the left atrium (oblique) ||
 * Inferior border || Formed by the right right ventricle and slightly by the left ventricle (horizontal) ||
 * Superior border || Only visible from anterior. Formed by the right and left atria. Superior vena cava, aorta, and pulmonary trunk emerge/enter from superior border. ||

= 7. Identify the following features: =

3 Grooves 5 Arteries + Aorta 4 Veins
 * Atrioventricular Groove (aka coronary groove or sulcus) || The groove on the right pulmonary surface of the heart dividing the atria from the ventricles ||
 * Anterior Interventricular Groove || The groove on the sternocostal surface of the heart dividing the r. ventricle from the l. ventricle ||
 * Posterior Interventricular Groove || The groove on the diaphragmatic surface of the heart dividing the l. ventricle from the r. ventricle ||
 * Ascending Aorta || Largest artery in body, outflow from left ventricle. ||
 * Left coronary a. || Co-first branch from aorta, runs underneath left auricle. ||
 * Anterior interventricular a. (aka LAD) || First branch from left coronary a. Runs down anterior interventricular sulcus ||
 * Circumflex a. || Termination of left coronary a. Runs around left pulmonary surface of heart ||
 * Right coronary a. || Co-first branch from aorta, runs underneath right auricle. ||
 * Posterior interventricular a. (aka PDA) || Branch from right coronary a. Runs down posterior interventricular sulcus. ||
 * Coronary sinus || The pooling area for all cardiac veins; dumps straight into right atrium; on posterior edge of base of heart. ||
 * Great coronary v. (aka Great cardiac v.) || Runs within the anterior interventricular groove and follows the LAD or anterior interventricular artery. Empties directly into coronary sinus. ||
 * Middle cardiac v. || Runs with posterior interventricular groove. Empties directly into coronary sinus. ||
 * Small cardiac v. || Runs with right coronary artery before it branches on diaphragmatic surface of heart. Empties into coronary sinus. ||

= 8. Define the following: =


 * Fibrous Pericardium || The tough external layer of the pericardium, continuous with the central tendon of the diaphragm ||
 * Serous Pericardium || The balloon in Dr. Copenhaver's most dangerous demonstration. It surrounds the heart in two layers, the visceral pericardium and the parietal pericardium. COA describes it as glistening (made of diamonds?). ||
 * Visceral Pericardium (aka epicardium) || The third layer of the heart is also the innermost layer of the pericardium. it is continuous with the parietal layer of the pericardium at the base of the heart. One cell layer thick. ||
 * Parietal Pericardium || Covers the internal surface of the fibrous pericardium. One cell layer thick. ||

= 9. Recognize and name the following features of the right atrium: = 4 wall structures 4 openings + 1 outpocketing 2 nodes = 10. Name the following landmarks of the right ventricle: =
 * Pectinate mm. || Muscles lining inner wall of right atrium ||
 * Superior vena cava || Entrance of de-oxygenated blood from upper limbs, head, neck, and thorax ||
 * Inferior vena cava || Entrance of de-oxygenated blood from abdomen, pelvis, and lower limbs ||
 * Orifice of coronary sinus || Entrance of deoxygenated blood from pericardial region ||
 * R. atrioventricular orifice (aka tricuspid orifice) || Exit of deoxygenated blood through tricuspid valve to right ventricle ||
 * Fossa ovalis || Prenatal opening to left atrium; closes at birth; oval depression on intertrial septum ||
 * Location of AV node || Contained by membranous septum, partly with atrioventricular septum and partly within interventricular septum. Deep to r. atrium ||
 * Location of SA node || On right side of entrance of superior vena cava to right atrium ||
 * Right auricle || Outpocketing of right atrium anteriorly ||
 * Crista terminalis || Ridge at place where pectinate mm. end and the smooth surface of the vena cava vessels begins ||
 * Interatrial septum || Wall between the left and right atria ||


 * Tricuspid valve (aka r. atrioventricular valve) ||  ||
 * trabeculae carnaea ||  ||
 * anterior, posterior, and septal cusps ||  ||
 * moderator band (aka septomarginal trabecula) ||  ||
 * chordae tendineae ||  ||
 * Pulmonary valve ||  ||
 * Anterior papillary m. ||  ||
 * Anterior, right, and left cusps ||  ||
 * Posterior papillary m. ||  ||
 * Infundibulum (aka conus arteriosus) ||  ||
 * Septal papillary m. ||  ||
 * Interventricular septum ||  ||

= 11. Name the following landmarks of the left atrium: =
 * Left auricle pulmonary veins (4) ||  ||
 * Muscularis pectinati ||  ||

= 12. Name the following structures of the left ventricle: =


 * Bicuspid (aka mitral or l. atrioventricular valve) ||  ||
 * Trabeculae carnaea ||  ||
 * Anerior and posterior cusps ||  ||
 * Aortic orifice ||  ||
 * Anterior papillary m. ||  ||
 * Aortic valve ||  ||
 * Posterior papillary m. ||  ||
 * Right, left, and posterior cusps ||  ||
 * Chordae tendineae ||  ||

= 13. Describe the blood flow through the chambers of heart. =

= 14. Identify the major components of the impulse-generating and impulse-conducting systems of the heart:=
 * Sinoatrial (SA) node (aka pacemaker) ||  ||
 * Atrioventricular (AV) node ||  ||
 * AV bundle of (His) ||  ||
 * Right bundle branch ||  ||
 * Left bundle branch ||  ||
 * Purkinje system ||  ||

= 15. List the effects of parasympathetics from the vagus nerve upon heart rate, contraction and coronary arteries. Repeat for sympathetics from the sympathetic trunk. (Both form cardiac plexus). =


 * 16. Name the location of the surface heart sounds for the four valves of the heart: **

pulmonary: 2nd rib interspace - left parasternal aortic: 2nd rib interspace - right parasternal tricuspid: 5th rib interspace - left parasternal bicuspid: 5th rib interspace - left mid clavicular

Apex of the heart Sinoatrial node Left ventricle Right ventricle Left auricle Inferior vena cava Superior vena cava Right atrium Pulmonary trunk Aortic arch
 * 17. In an X-ray of the thorax, locate the approximate locations of the following structures: **