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Chapter 2: FUNCTIONAL ANATOMY OF THE HEART TOMOGRAPHIC METHOD

Renaissance anatomists such as da Vinci used the tomographic approach principally because of its artistic correlations.2 Modern anatomists and pathologists have resorted to this method because it correlates with conventional diagnostic tomographic-anatomic techniques. With this method, cardiac dissection involves bisecting the heart into two pieces using a single plane of section.6 Anatomy contained within the depth of each section fosters a perception of three-dimensional anatomy. Commonly used planes bisect the heart perpendicular to the base-apex axis (short-axis "transverse" views) (B+;0= Fig. 2-9, Plate 4) or parallel to it (long-axis and four-

chamber "frontal" views)6 Fig. 2-10, Plate 5). Planes that bisect the heart parallel to the conventional body planes (frontal "coronal", transverse "short-axis", and sagittal "long-axis" views) Fig. 2-11, Plate 6) replicate body tomographyM^-

The short-axis tomographic plane&J- of the heart (Q-hB; Fig. 2-12) are similar to the ventricular slice method but differ in two important respects. The "bread slicing" of the heart is continued to the base of the heart and great vessels, and the slices are oriented as though the heart were being viewed from the apex toward the base rather than in the opposite direction, as has been the case with the ventricular slice technique. Photographs should correspond with diagnostic tomographic scans.

The long-axis and four-chamber planes are orthogonal to the short-axis planes. The four-chamber planes of cardiac dissection (Fig. 2-13) involve sectioning the heart along both lateral walls, from apex to base, such that both ventricles and both atria are included in the plane of section.67 The long-axis two-chamber method (Fig. 2-14) involves bisecting the heart from the left ventricular apex through the mitral orifice and into the left atrium.67 The long-axis plane can cut through both the left ventricular inflow tract (including the left atrium and mitral valve) and the left ventricular outflow tract (including the ventricular septum, anterior mitral leaflet, and ascending aorta) (Fig. 2-15). This plane also cuts obliquely through the right ventricular outflow tract.6,7

Figure Right Ventricular Outflow Tract

Figure 2-13: Tomographic cardiac dissection along the heart's primary fourchamber plane. The heart is viewed as though one were looking from the anterosuperior surface toward the posteroinferior surface. In the floor of the right atrium is the orifice of the inferior vena cava (IVC). The pulmonary veins (PulV) enter the posterior aspect of the left atrium. AL, anterolateral mitral papillary muscle; AS, atrial septum; LA, left atrium; LV, left ventricle; MV, mitral valve; PM, posteromedial mitral papillary muscle; RV, right ventricle; TV, tricuspid valve; VS, ventricular septum.

Figure 2-13: Tomographic cardiac dissection along the heart's primary fourchamber plane. The heart is viewed as though one were looking from the anterosuperior surface toward the posteroinferior surface. In the floor of the right atrium is the orifice of the inferior vena cava (IVC). The pulmonary veins (PulV) enter the posterior aspect of the left atrium. AL, anterolateral mitral papillary muscle; AS, atrial septum; LA, left atrium; LV, left ventricle; MV, mitral valve; PM, posteromedial mitral papillary muscle; RV, right ventricle; TV, tricuspid valve; VS, ventricular septum.

Left Ventricle Papillary Muscle

Figure 2-14: Tomographic cardiac dissection along the heart's primary long-axis plane. A. Tomographic section showing the left ventricle and left atrium. The mitral valve is also well demonstrated. The left atrial appendage is located anteriorly. The specimen is viewed as though one were looking from the tip of the left scapula toward the right nipple. B. Analogous two-chamber transesophageal view. AW, anterior wall; Desc Ao, descending thoracic aorta; E, esophagus; IW, inferior wall; LA, left atrium; LAA, left atrial appendage; LB, left bronchus; LPA, left pulmonary artery; LV, left ventricle; MV, mitral valve; PulV, pulmonary vein; Tr, trachea.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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