What Is the Atrial or Posterior Input to the AVN?
A comparison of histological data for the atrial or posterior input identified by other workers with histological data presented here identifies these structures as ordinary myocardium of the medial atrial wall and, by and large, as various parts of its annular myocardium: terminals of internodal tracts (James, 14 Figures 2B, 6, 7, and 9; James, 23 Figures 6C and 6D), the rightward component of the compact AVN (Becker and Anderson, 16 Figure 8A; Inoue and Becker, 19 Figures 2B, 3, and 5 to 7), the overlay and transitional myofibers (James, 14 Figures 2A and 3B; Becker and Anderson, 16 Figure 2A), with the posterior nodal extension and compact AVN (Medkour et al, 24 Figure 2) and the AV nodal ring input being analogous to part or all of the circumferential lamina encircling the tricuspid valve (McGuire et al, 25 Figures 11 and 12) and all of the ordinary atrial myocardium of the AV junction region (Sanchez-Quintana et al, 18 Figure 2). Moreover, the PAVB is aligned with the medial or up
