The sinus venarum and the atrium meet at the muscular ridge called ______ .

Appeared in: UP CHO - 10 September 2021

Explanation

The crista terminalis is a distinct, C-shaped muscular ridge located on the internal surface of the right atrium.
It serves as the boundary separating the smooth-walled posterior part of the atrium, known as the sinus venarum, from the rough-walled anterior part containing the pectinate muscles.
The sinus venarum is where the superior and inferior venae cavae and the coronary sinus open, delivering deoxygenated blood to the heart.
Externally, this internal ridge corresponds to a groove called the sulcus terminalis.

Option B: The fossa ovalis is a shallow depression, not a ridge. It is located on the interatrial septum, which separates the right and left atria.
Option C: The auricle, or right atrial appendage, is a small, muscular pouch that extends from the main chamber of the atrium. It is part of the rough-walled atrium but not the ridge that divides the atrium.
Option D: The venae cordis minimae (also known as Thebesian veins) are numerous, very small veins within the muscular walls of the heart. They drain blood directly into the chambers but do not form a large, singular muscular ridge.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the Right Atrium as background academic context rather than a clinical decision trigger.
The crista terminalis is a critical anatomical landmark for electrophysiologists during procedures like catheter ablation for atrial arrhythmias.
It is a common site for the origin of re-entrant tachycardias, such as typical atrial flutter, due to its unique muscle fiber arrangement.
The sinoatrial (SA) node, the heart's natural pacemaker, is located at the superior end of the crista terminalis.

How to Approach the Question

This is a factual recall question testing knowledge of cardiac anatomy.
First, identify the key terms in the question: 'sinus venarum,' 'atrium,' and 'muscular ridge.'
Recall the internal structures of the right atrium. The right atrium is known to have a smooth part (sinus venarum) and a rough part (atrium proper with pectinate muscles).
The question asks for the name of the specific ridge that separates these two distinct parts.
Evaluate the options based on your anatomical knowledge:
The crista terminalis is defined as a ridge in the right atrium.

Concept Tested & Keywords

QGmCDxxXs6Ub-IxuHZaUuF

E6 Anatomy Applied Ashalatha 4e p. 162-164

E6 Anatomy Grays 43e Vol 1 Part 2 p. 40-42

Practise the full UP CHO - 10 September 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.