Lab Manual - Heart

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Identify the structures traversed in sequence of blood flow. Relate the anatomy of the heart to its basic physiological function. (explanation)
  2. Identify the structures found in each of the four chambers and consider their significance. (explanation)
  3. Compare and contrast the anatomical characteristics right and left sides of the heart. (explanation)
  4. Identify the arterial supply and venous drainage of the heart. Describe the electrical conduction system. (explanation)
  5. Describe the sternocostal projections of the valves of the heart and identify their auscultation points. (explanation)

Readings and Modules:

Procedure:

1. Remove the heart from the pericardial cavity and examine its features. (Play movie; View images: N 206, 212, 215, 216, 241, TG 4-19, 4-20, 4-21)

Remove the heart from the pericardial cavity by placing your finger in the transverse sinus and cutting through the aorta and pulmonary trunk as they leave the heart, inside of the pericardium. Sever the superior and the inferior venae cavae as they enter the right atrium. Identify the four pulmonary veins on the posterior surface of the heart and, working from the oblique sinus, cut each. Review the cut edges of the pericardial reflection both on the heart and on the posterior wall of the pericardial cavity. Carefully examine the removed heart, using borders, surfaces, sulci, and great vessels for proper orientation.

2. Remove the epicardium and identify the coronary blood vessels. (Play movie; View images: N 212, 214, 215, 216A, 216B, 218, 219, 220, 222, 225, TG 4-19, 4-21A, 4-21B, 4-22A, 4-22B, 4-23A, 4-23B, 4-24A, 4-24B, 4-24C, 4-24D, 4-25, 4-28)

Carefully remove the epicardium (visceral pericardium) and epicardial fat. Clean the aorta near its base and locate the right coronary artery; follow it into the coronary sulcus. Care must be taken to avoid damage to the small anterior cardiac veins that cross the artery superficially. Identify the following branches: artery of the sinoatrial node (small artery that usually encircles the dorsal side of superior vena cava; may arise from right coronary or circumflex branch of left coronary a.), ventricular branches, the right marginal artery, atrial branches, the posterior interventricular (descending or PDA) artery (in posterior interventricular sulcus), septal arteries (entering the interventricular septum from the posterior interventricular a.). The small cardiac vein accompanies the right coronary artery on the back of the heart.

Return to the base of the aorta and find the left coronary artery. Trace the anterior interventricular (descending or LAD) artery in the anterior interventricular sulcus. It is accompanied by the great cardiac vein. Look for septal branches of the anterior interventricular artery. Trace the circumflex artery. A left marginal artery may arise from the anterior interventricular or the circumflex artery. Note atrial branches. Trace the circumflex artery to its termination deep to the coronary sinus. Check for anastomoses with terminals of the right coronary. Locate the artery to the atrioventricular node deep in the coronary sulcus at the plane of the interatrial septum. Is it a branch of the right or left coronary artery or both? The artery of the AV node usually arises from the right coronary artery just as it turns downward to enter the posterior interventricular sulcus. Determine the source of the posterior interventricular artery. In a left dominant heart (15%), the circumflex artery gives rise to the posterior interventricular.

Trace the great cardiac vein, the posterior vein of the left ventricle and the middle cardiac vein to the coronary sinus (thin- walled, sometimes covered with muscle fibers). Define anterior cardiac and small cardiac veins. Review the cardiac plexus and its distribution along the coronary vessels.

3. Open the chambers of the heart as shown in Figure 6. (Play movie) and 4. Clean out the chambers and identify their anatomical features. (Play movie; View images: N , 212, 214, 220A, 220B, 221A, 221B, 222A, 222B, 223A, 223B, 224, 225, TG 4-14, 4-21, 4-25A, 4-25C, 4-26A, 4-26B, 4-27, 4-28)

Examine the chambers of the heart by opening them in the sequence of the blood flow. Use incisions indicated in Fig. 6. The chambers are usually filled with coagulated blood that must be carefully removed in order to preserve delicate structures within. Wash out the cardiac chambers to remove remaining small clots.

Right atrium. Examine the auricle. Define endocardium. Observe: openings of the superior and inferior venae cavae (valve of inferior vena cava) and coronary sinus (valve), the crista terminalis (relate to external sulcus terminalis), pectinate muscle, fossa ovalis (and its limbus on interatrial septal wall). Check for patency of fossa ovalis (valvula foramina ovalis) to left atrium. Consider the significance of venous and arterial blood mixing when the opening is large. Examine the right atrioventricular (tricuspid) valve, define cusps.

Right ventricle. Note thickness of myocardium and arrangement of trabeculae carneae. Define chamber walls: interventricular, anterior and posterior. Define papillary muscles (anterior, posterior, and septal), chordae tendineae, and tricuspid valve cusps (anterior, posterior and septal). Consider functions of the valve. Do you find a septomarginal trabecula (moderator band)? Examine the conus arteriosus (pulmonary conus) leading to the pulmonary valve. Examine the semilunar cusps, their structure and sinuses. Name the various cusps.

Left atrium. Identify the openings of four pulmonary veins. On the interatrial septum look for evidence of a valvula foramina ovalis. Examine the auricle and its musculature. Examine the left atrioventricular (mitral or bicuspid) valve, its anterior and posterior cusps; does it have any commissural cusps? Note relation of anterior cusp to aortic wall.

Left ventricle. Observe the thickness of the ventricular walls and compare with the right ventricle. Note trabeculae carneae musculature; define the interventricular septum and its muscular and membranous portions. What is the aortic vestibule? Observe the anterior and posterior papillary muscles with their chordae tendineae attaching indistinctly to both anterior and posterior cusps. Examine the aortic valve and its semilunar cusps. Name them. Examine the valve sinuses related to the origin of the right and left coronary arteries.

Now consider the position of the valves of the heart in reference to the chest wall. Where are the sounds associated with each valve best heard with a stethoscope?

Surface anatomy
Surface anatomy and hear heart sounds

Make a vertical incision along the obtuse border of the heart from its apex through the coronary sulcus, the left atrioventricular valve and atrial wall. What is the anulus fibrosus (fibrous ring)?

Consider the structural arrangement of the cardiac musculature relative to the fibrous skeleton of the heart (tricuspid and mitral fibrous rings, aortic and pulmonary fibrous sleeves, and interconnecting connective tissue). What is the relationship of the skeleton to the conduction system? Significance?

3D images of the heart
CT of atria and ventricles

Updated: 30 Sep 2011