
Atrioventricular bundle
The lower portion of the membranous septum of the interventricular septum contains the atrioventricular bundle (of His), a continuation of the conducting system from the AV node. The AV bundle splits into right and left bundle branches supplying their respective ventricles. Bundle branches continue as Purkinje fibers, which innervate the ventricular myocardium. 400x

Atrioventricular bundle
The lower portion of the membranous septum of the interventricular septum contains the atrioventricular bundle (of His), a continuation of the conducting system from the AV node. The AV bundle splits into right and left bundle branches supplying their respective ventricles. Bundle branches continue as Purkinje fibers, which innervate the ventricular myocardium. 400x

Left bundle branch
The lower portion of the membranous septum of the interventricular septum contains the atrioventricular bundle (of His), a continuation of the conducting system from the AV node. The AV bundle splits into right and left bundle branches supplying their respective ventricles. Bundle branches continue as Purkinje fibers, which innervate the ventricular myocardium. 400x

Right bundle branch
The lower portion of the membranous septum of the interventricular septum contains the atrioventricular bundle (of His), a continuation of the conducting system from the AV node. The AV bundle splits into right and left bundle branches supplying their respective ventricles. Bundle branches continue as Purkinje fibers, which innervate the ventricular myocardium. 400x

Myocardium
The lower portion of the membranous septum of the interventricular septum contains the atrioventricular bundle (of His), a continuation of the conducting system from the AV node. The AV bundle splits into right and left bundle branches supplying their respective ventricles. Bundle branches continue as Purkinje fibers, which innervate the ventricular myocardium. 400x

Endocardium >
The endocardium is composed of an endothelium resting on a thin connective tissue layer. This connective tissue, in turn, blends with a thicker, denser connective tissue, which composes the bulk of the endocardium. Between endocardium and myocardium is another layer, the subendocardium, composed of connective tissue containing bundle branches.

- Endothelium
The endocardium is composed of an endothelium resting on a thin connective tissue layer. This connective tissue, in turn, blends with a thicker, denser connective tissue, which composes the bulk of the endocardium. Between endocardium and myocardium is another layer, the subendocardium, composed of connective tissue containing bundle branches.

- Connective tissue layers
The endocardium is composed of an endothelium resting on a thin connective tissue layer. This connective tissue, in turn, blends with a thicker, denser connective tissue, which composes the bulk of the endocardium. Between endocardium and myocardium is another layer, the subendocardium, composed of connective tissue containing bundle branches.

- Subendocardium
The endocardium is composed of an endothelium resting on a thin connective tissue layer. This connective tissue, in turn, blends with a thicker, denser connective tissue, which composes the bulk of the endocardium. Between endocardium and myocardium is another layer, the subendocardium, composed of connective tissue containing bundle branches.