The terminal sulcus is a groove on the outer surface of the

right atrium The atrium (; : atria) is one of the two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular mitral and tricuspid heart valves. ...

of the

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

marking the transition between the sinus venarum cavarum (which has a distinct embryological origin) and the rest of the right atrium (which features pectinate muscles on its inner surface). The terminal sulcus corresponds to the position of the terminal crest on the inner surface of the right atrium. The terminal sulcus (and crest) indicate the position of the

sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node, sinus node or Keith–Flack node) is an ellipse, oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of Cell (biology), cells known as pa ...

Anatomy

The terminal sulcus extends from the front of the

superior vena cava The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vei ...

to the front of the

inferior vena cava The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart. It is formed by the joining of the right and the left common iliac veins, usually at the level of the ...

, and represents the line of union of the

sinus venosus The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. In mammals, the sinus venosus exists distinctly only in the embryonic heart where it is found between the two venae cavae; i ...

of the

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

with the primitive atrium. The superior border of the terminal sulcus designates the transverse plane in which the SA node resides. The inferior border designates the transverse plane in which the AV node resides.

References

Cardiac anatomy {{circulatory-stub