Regarding the heart, [a] Phrenic nerve lies anteriolateral to pericardium. [b] Crista terminalis is represented by the sulcus terminalis on the exterior. [c] Right margin is formed by the right atrium. [d] Costal surface is mainly formed by the left ventricle. [e] In a part of its course left coronary artery is between aorta and right atrium. [f] Anterior cusp of the mitral valve lies posterior to the aortic vestibule. [g] Diaphragmatic surface is mainly formed by left ventricle. [h] Middle cardiac vein lies in the posterior interventricular sulcus. [i] [j] Right ventricle is circular in cross section. The anterior interventricular sulcus lies along its left border. [k] The fossa ovalis is seen in the anterior wall of the right atruium. [l] Anterior cusp of the mitral valve is between the aortic orifice and the atrioventricular sulcus. [m] In X-Rays images its right border is formed by the right atrium. [n] The circumflex branch supplies part of the right posterior interventricular sulcus. [o] Interventricular septum lies in the coronal plane. [p] Right coronary artery supplies the posterior one third [1/3] of the interventricular septum. Answer the question like true or false and explain why this is MRCS question and explain should be expert level
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I now have all the information needed from the authoritative textbooks to give a thorough expert-level MRCS analysis. Let me compile the complete answer.
Here is a complete expert-level MRCS analysis of each statement:
[a] Phrenic nerve lies anterolateral to the pericardium — FALSE
The phrenic nerve lies lateral to the pericardium (between the mediastinal pleura and the pericardium), not anterolateral. Anatomically, the phrenic nerve descends through the thoracic cavity passing between the mediastinal pleura and the fibrous pericardium on each side. The classic surgical landmark is that pericardiectomy involves resection from "phrenic to phrenic," meaning the nerve flanks the lateral border. The Color Atlas of Human Anatomy (Vol. 2) explicitly states the phrenic nerve runs bilaterally between the pleura and pericardium, accompanying the pericardiacophrenic artery and vein. "Anterolateral" is incorrect - it is simply lateral (or more precisely, on the lateral aspect of the pericardium).
[b] Crista terminalis is represented by the sulcus terminalis on the exterior — TRUE
This is a direct anatomical correlation. The crista terminalis is the internal muscular ridge in the right atrium separating the smooth-walled sinus venarum (derived from the sinus venosus) posteriorly from the trabeculated atrium proper (with pectinate muscles) anteriorly. Its external counterpart is the sulcus terminalis cordis, a shallow groove on the outer surface running from the right side of the SVC opening to the right side of the IVC opening. Gray's Anatomy for Students confirms: "Externally, this division is indicated by the sulcus terminalis cordis... Internally, by the crista terminalis." This is a classic MRCS topographical correlation.
[c] Right margin is formed by the right atrium — TRUE
In the anatomical position, the right border (right pulmonary surface) of the heart is formed by the right atrium. Gray's Anatomy for Students (line 5945) states directly: "In the anatomical position, the right border of the heart is formed by the right atrium. This chamber also contributes to the right portion of the heart's anterior surface." This is an unambiguous TRUE.
[d] Costal (anterior) surface is mainly formed by the left ventricle — FALSE
The costal/anterior surface is formed mainly by the right ventricle, not the left ventricle. Gray's Anatomy for Students states: "In the anatomical position, the right ventricle forms most of the anterior surface of the heart." The left ventricle forms the apex and contributes to the left pulmonary surface (left lateral border) and the diaphragmatic surface, but the sternocostal/anterior surface is predominantly right ventricular. This is a very commonly tested MRCS point.
[e] In part of its course, the left coronary artery is between the aorta and the right atrium — FALSE
The left coronary artery arises from the left aortic sinus and passes between the pulmonary trunk and the left auricle (not the right atrium) before entering the coronary sulcus. Gray's Anatomy for Students (line 6186) explicitly states: "It passes between the pulmonary trunk and the left auricle before entering the coronary sulcus." The structure that runs between the aorta and right atrium is the right coronary artery (it passes in the groove between the right auricle and ascending aorta). So statement [e] has the wrong structures - the left coronary artery's proximal course is between the aorta/pulmonary trunk and the left auricle.
[f] Anterior cusp of the mitral valve lies posterior to the aortic vestibule — FALSE
This is the reverse of the correct relationship. The anterior (aortic) leaflet of the mitral valve is continuous with / adjacent to the aortic vestibule - it actually forms part of the wall separating the left ventricular outflow tract (aortic vestibule) from the inflow. The anterior mitral cusp is sometimes called the "aortic cusp" precisely because it is in fibrous continuity with the aortic valve annulus. It lies at the posterior wall of the aortic vestibule / outflow tract, not posterior to it in the sense of being behind it. If anything, the anterior cusp faces the aortic vestibule anteriorly. See statement [l] below for the correct anatomical description.
[g] Diaphragmatic surface is mainly formed by the left ventricle — TRUE
The diaphragmatic (inferior) surface of the heart rests on the diaphragm and is formed predominantly by the left ventricle, with a smaller contribution from the right ventricle. Gray's Anatomy for Students confirms the left ventricle "contributes to the anterior, diaphragmatic, and left pulmonary surfaces of the heart." The posterior interventricular sulcus runs along this surface, and the left ventricle constitutes roughly two-thirds of the diaphragmatic surface. TRUE.
[h] Middle cardiac vein lies in the posterior interventricular sulcus — TRUE
This is a well-established anatomical fact. The posterior interventricular sulcus (on the diaphragmatic surface) contains the posterior interventricular artery (usually from the right coronary artery) and the middle cardiac vein. Gray's Anatomy for Students (line 5902) states: "the posterior interventricular sulcus is on the diaphragmatic surface of the heart and contains the posterior interventricular artery and the middle cardiac vein." Fischer's Mastery of Surgery confirms: "The middle cardiac vein starts at the apex of the heart and courses in the posterior interventricular sulcus to the right end of the coronary sinus." TRUE.
[i] (No statement listed - item [i] appears to have been omitted from the question.)
[j] Right ventricle is circular in cross section — FALSE
The right ventricle in cross-section has a crescent or D-shaped profile, not circular. This is because the interventricular septum bulges into the right ventricular cavity (it is convex toward the right ventricle). The left ventricle is the one with a circular/elliptical cross-section. The crescent shape of the right ventricle is functionally important - it allows efficient volume pumping at low pressure using a "bellows" mechanism. The circular cross-section is characteristic of the left ventricle. FALSE.
"The anterior interventricular sulcus lies along its [right ventricle's] left border" — FALSE
The anterior interventricular sulcus lies along the left border of the right ventricle (i.e., it separates the right ventricle from the left ventricle), but calling it the "left border" of the right ventricle is anatomically imprecise. The sulcus marks the boundary between the two ventricles on the anterior surface, and it does course along what could be considered the left/posterolateral margin of the right ventricle. However, the anterior interventricular sulcus actually contains the LAD (left anterior descending artery) and great cardiac vein, and defines the right ventricular boundary on its left side. Technically TRUE that it runs along the left (septal) margin of the right ventricle as seen anteriorly, but this is an unusual and potentially confusing way to describe it.
[k] The fossa ovalis is seen in the anterior wall of the right atrium — FALSE
The fossa ovalis is located in the interatrial septum, not the anterior wall. Gray's Anatomy for Students (line 5975) states: "Separating the right atrium from the left atrium is the interatrial septum, which faces forward and to the right... A depression is clearly visible in the septum just above the orifice of the inferior vena cava. This is the fossa ovalis." The interatrial septum is the medial/posterior wall of the right atrium, not the anterior wall. The anterior wall of the right atrium is occupied by the atrium proper with pectinate muscles and the right auricle. FALSE.
[l] Anterior cusp of the mitral valve is between the aortic orifice and the atrioventricular orifice — TRUE
This is the correct anatomical description. The anterior (aortic) cusp of the mitral valve is positioned between the left atrioventricular orifice (mitral orifice) posteriorly and the aortic orifice (aortic vestibule/outflow tract) anteriorly. This is why it is also called the "aortic cusp" - it is in fibrous continuity with the posterior wall of the aortic root (specifically the left and noncoronary aortic sinuses). During diastole, this cusp swings open into the ventricular cavity dividing inflow from outflow. TRUE.
[m] In X-ray images, the right border is formed by the right atrium — TRUE
On a standard posteroanterior (PA) chest X-ray, the right cardiac border is formed (from top to bottom) by: the superior vena cava (upper portion) and the right atrium (lower portion). Gray's Anatomy for Students (line 5893) confirms: "The right border in a standard posteroanterior view consists of the superior vena cava, the right atrium, and the inferior vena cava." So the dominant contributor to the right border on CXR is the right atrium. TRUE.
[n] The circumflex branch supplies part of the right posterior interventricular sulcus — FALSE (in most people; sometimes TRUE as a variant)
In a standard right-dominant coronary circulation (present in ~70% of people), the right coronary artery gives rise to the posterior descending/posterior interventricular artery which supplies the posterior interventricular sulcus. The circumflex branch of the left coronary artery normally ends before reaching the posterior interventricular sulcus (Gray's line 6192: "usually ends before reaching the posterior interventricular sulcus"). However, in a left-dominant circulation (~15-20%), the circumflex artery does supply the posterior interventricular sulcus. For MRCS purposes, the default answer is FALSE (in most people it is the right coronary artery that supplies the posterior interventricular sulcus). Note this is the exact converse of statement [p].
[o] Interventricular septum lies in the coronal plane — FALSE
The interventricular septum does not lie in the coronal plane. It lies roughly in the sagittal or oblique plane, angling from the front-left to the back-right. The heart is rotated in the thorax such that the right ventricle faces anteriorly and the left ventricle faces posteriorly and to the left. The interventricular septum, which separates the two ventricles, is therefore oriented in an oblique plane - roughly sagittal but tilted. On cross-sectional imaging, it runs antero-posteriorly, not side-to-side (coronal). FALSE.
[p] Right coronary artery supplies the posterior one-third of the interventricular septum — TRUE
This is the standard teaching. The interventricular septum receives a dual blood supply:
- Anterior two-thirds: supplied by the anterior interventricular (LAD) branch of the left coronary artery via septal perforators
- Posterior one-third: supplied by the posterior interventricular branch of the right coronary artery (in a right-dominant circulation)
Gray's Anatomy for Students (line 6182-6184) confirms: "The right coronary artery supplies... the posteroinferior one-third of the interventricular septum." This is a highly tested MRCS/anatomy point, especially relevant to understanding which vessel occlusion causes which type of heart block (e.g., RCA occlusion can cause AV block because the AV node and the posterior septum - where the bundle of His runs - are supplied by the RCA). TRUE.
Summary Table
| Statement | True/False |
|---|---|
| [a] Phrenic nerve anterolateral to pericardium | FALSE - it is lateral (between pleura and pericardium) |
| [b] Crista terminalis = sulcus terminalis externally | TRUE |
| [c] Right margin formed by right atrium | TRUE |
| [d] Costal surface mainly formed by left ventricle | FALSE - mainly right ventricle |
| [e] Left coronary artery between aorta and right atrium | FALSE - it passes between pulmonary trunk and left auricle |
| [f] Anterior mitral cusp lies posterior to aortic vestibule | FALSE - it lies adjacent to/continuous with the aortic vestibule |
| [g] Diaphragmatic surface mainly formed by left ventricle | TRUE |
| [h] Middle cardiac vein in posterior interventricular sulcus | TRUE |
| [i] (No statement) | - |
| [j] Right ventricle circular in cross section | FALSE - it is crescent/D-shaped |
| [k] Fossa ovalis in anterior wall of right atrium | FALSE - it is in the interatrial septum |
| [l] Anterior mitral cusp between aortic orifice and AV orifice | TRUE |
| [m] X-ray right border = right atrium | TRUE |
| [n] Circumflex supplies part of right posterior IV sulcus | FALSE (in right-dominant hearts - the norm) |
| [o] Interventricular septum in coronal plane | FALSE - it is in an oblique/sagittal plane |
| [p] RCA supplies posterior 1/3 of IV septum | TRUE |
Key MRCS high-yield points from this set:
- Anterior surface = right ventricle; diaphragmatic surface = mainly left ventricle
- Left coronary artery passes between pulmonary trunk and left auricle (not aorta and right atrium)
- Right ventricle is crescent-shaped, not circular (left ventricle is circular)
- Fossa ovalis is in the interatrial septum (medial wall), not the anterior wall of the right atrium
- RCA (posterior 1/3) and LAD (anterior 2/3) supply the interventricular septum - clinically critical for heart block localization
Sources: Gray's Anatomy for Students (9780323934237), Color Atlas of Human Anatomy Vol. 2 (9783132424487), Fischer's Mastery of Surgery 8th ed.
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