Henry Gray (18251861). Anatomy of the Human Body. 1918.
are connected below with the right ventricle, and medially with the left atrium, but are free in the rest of their extent.
Auricula (auricula dextra; right auricular appendix).The auricula is a small conical muscular pouch, the margins of which present a dentated edge. It projects from the upper and front part of the sinus forward and toward the left side, overlapping the root of the aorta.
The separation of the auricula from the sinus venarum is indicated externally by a groove, the terminal sulcus, which extends from the front of the superior vena cava to the front of the inferior vena cava, and represents the line of union of the sinus venosus of the embryo with the primitive atrium. On the inner wall of the atrium the separation is marked by a vertical, smooth, muscular ridge, the terminal crest. Behind the crest the internal surface of the atrium is smooth, while in front of it the muscular fibers of the wall are raised into parallel ridges resembling the teeth of a comb, and hence named the musculi pectinati.
Its interior (Fig. 493) presents the following parts for examination:
Superior vena cava.
Inferior vena cava.
Valve of the inferior vena cava.
Foramina venarum minimarum.
Valve of the coronary sinus.
Limbus fossæ ovalis.
The superior vena cava returns the blood from the upper half of the body, and opens into the upper and back part of the atrium, the direction of its orifice being downward and forward. Its opening has no valve.