Carotid sinus

Bulbospongiosus muscle

The development of the heart begins in the precardium, which is a specialized region of splanchnic mesoderm located in front of the developing foregut. Cells from the precardium form two endocardial heart tubes. As embryonic folding occurs, these paired heart tubes move toward the midline and fuse to form a single primitive heart tube. The primitive heart tube then differentiates into specific regions arranged from tail to head: the sinus venosus, primitive atrium, primitive ventricle, bulbus co