Examine the right atrioventricular valve, and identify its three cusps [cross-section]: an anterior cusp [held by the forceps], a septal cusp, and a posterior cusp [indicated by probe; forceps hold chordae tendineae of anterior cusp]. The names of the cusps indicate their relative positions (Figure 20.7).
Identify the chordae tendineae, the small fibrous cords, that extend from the cusps of the tricuspid valve to three papillary muscles. The anterior papillary muscle is the largest of the three papillary muscles and is attached to the inferior border of the anterior wall. The posterior papillary muscle [probe] is a relatively large muscle located on the posterior wall. The septal papillary muscles are small and often multiple.
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