Coronary Artery Anatomy and Branches

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Questions and Answers

What is the origin of the Right Coronary Artery?

Pulmonary trunk

Coronary sinus

Left aortic sinus

Right aortic sinus (correct)

Which of the following structures is supplied by the Right Coronary Artery in approximately 60% of patients?

Left atrium

Left ventricle

Interventricular septum

SA Node (correct)

What is the largest branch of the Right Coronary Artery?

Circumflex artery

Artery to AV Node

Posterior descending artery (PDA) (correct)

Right Marginal Artery

Which artery is typically associated with the Left Coronary Artery as its major branches?

Circumflex artery Signup and view all the answers

Which anatomical feature does the Left Coronary Artery emerge between?

Left auricle and pulmonary trunk Signup and view all the answers

In which part of the heart does the Circumflex artery continue to supply?

Posterior wall Signup and view all the answers

What is the term used to describe the connection between the Right Coronary Artery and the Circumflex artery?

Anastomosis Signup and view all the answers

What coronary artery supplies the anterior interventricular area of the heart?

Left Anterior Descending Artery Signup and view all the answers

What is the primary location affected by a blockage in the Left Anterior Descending (LAD) artery?

Left ventricle Signup and view all the answers

In a right dominant heart, which artery primarily supplies the posterior interventricular septum?

Right coronary artery Signup and view all the answers

Which term is used to describe the occlusion in the LAD that often leads to high mortality?

Widowmaker Signup and view all the answers

Which type of cardiac veins drain blood directly into the heart's chambers?

Smallest cardiac veins (venae cordis minimi) Signup and view all the answers

What is commonly associated with myocardial ischemia?

Angina pectoris Signup and view all the answers

Which artery has the least likelihood of being occluded compared to other coronary arteries?

Left circumflex artery Signup and view all the answers

What is the main function of the coronary sinus in the heart?

Drain deoxygenated blood from the heart muscle Signup and view all the answers

What percentage of patients typically exhibit right dominance in coronary artery supply?

70% Signup and view all the answers

What initiates the electrical signal in the heart?

SA Node Signup and view all the answers

What is the primary function of the sympathetic supply to the heart?

To enhance heart rate and contractility during stress Signup and view all the answers

Where do the sympathetic fibers that supply the heart originate?

Thoracic spinal cord at T1-T5 level Signup and view all the answers

Which nerve conveys parasympathetic signals to the cardiac plexus?

Vagus Nerve (CN X) Signup and view all the answers

Which dermatome is commonly associated with referred pain from cardiac ischemia?

T1-T5 Signup and view all the answers

Where is the AV Node located?

In the interatrial septum near the coronary sinus Signup and view all the answers

What type of pain is associated with irritation of the pericardium during cardiac ischemia?

Left shoulder and neck pain Signup and view all the answers

What part of the heart supplies the electrical signal to the ventricles?

AV bundle Signup and view all the answers

What event marks the closure of the semilunar valves during the cardiac cycle?

Ventricular relaxation Signup and view all the answers

Which phase of the cardiac cycle allows for passive filling of the ventricles?

Ventricular diastole Signup and view all the answers

What percentage of the end diastolic volume is provided by atrial contraction?

25-30% Signup and view all the answers

What heart sound may occur due to atrial pressure increase in hypertensive patients?

Fourth heart sound (S4) Signup and view all the answers

What follows the closure of the AV valves in the cardiac cycle?

Isometric contraction Signup and view all the answers

Study Notes

Right Coronary Artery

Originates from the ascending aorta (right aortic sinus)
Emerges between the right auricle and pulmonary trunk
Runs downwards in the coronary sulcus
Continues posteriorly in the same groove until it anastomoses with the Circumflex branch of the left coronary artery

Right Coronary Artery Branches

Artery to SA Node & AV Node (supplies these nodes in ~60% of patients)
Posterior descending artery (PDA) or Posterior Interventricular A. (supplies this artery in ~70% of patients)
Right Marginal Artery

Left Coronary Artery

Originates from the Ascending aorta (left aortic sinus)
Emerges between the left auricle and pulmonary trunk, then runs in the coronary sulcus
Divides into the Anterior interventricular (1) & Circumflex arteries (2)
Circumflex artery continues in the coronary sulcus to the back of the heart and anastomoses with the terminal part of the right coronary artery

Left Coronary Artery Branches

Left Anterior Descending Artery (LAD) or Anterior Interventricular A.
Circumflex Artery (can supply SA node, AV node or PDA in a minority of patients)
Left Marginal Artery branch from Circumflex artery

Clinical Anatomy

Coronary blockage is most likely to occur in the LAD (~40-50% of all cases)
Obstructs most of the blood supply to the left ventricle
Often requires surgical bypass

Myocardial Ischemia

Angina pectoris
Myocardial Infarction

Right vs. Left Coronary Dominance

RCA dominance is more common (~70% of patients)
LCA dominance is less frequent
Co-dominance (roughly equal contribution from LCA and RCA) is also less frequent

Venous Drainage of the Heart

Coronary sinus: main vein of the heart
Anterior cardiac veins: from the anterior wall of the right ventricle
Smallest cardiac veins (venae cordis minimi)

Coronary Sinus

Drains blood from heart tissue to the right atrium
Tributaries include:
- Great Cardiac Vein: travels with the anterior interventricular artery (LAD)
- Middle Cardiac Vein: travels with the posterior interventricular artery (PDA)

Innervation of the Heart

Sympathetic Supply (Fight or Flight): fibers originate in Intermedolateral cell column (IML) of spinal cord at T1-T5 level
Parasympathetic Supply (Rest and Digest): Vagus Nerves (CN X) descend from the brain to enter the cardiac plexus

Cardiac Ischemia Pain

Left chest wall/left upper limb pain (referred pain associated with T1-T5 dermatome)
Left shoulder and neck pain (referred pain associated with C3-C5 dermatome)

Cardiac Plexus

Sympathetic: Nerves that originate in T1-T5 level of spinal cord; synapse at the sympathetic trunk; cardiopulmonary splanchnic nerves then travel to the cardiac plexus
Parasympathetic: Vagus Nerves (CN X) descend to feed into the cardiac plexus

Conducting System of the Heart

SA Node initiates signal
Signal is transmitted myogenically to the AV node
Signal is then transmitted to the ventricles via the AV bundle in the ventricular walls regulating contraction of ventricles/papillary muscles

Ventricular Diastole

Ventricular relaxation leads to a decrease in ventricular pressure, causing the closure of semilunar valves and producing the second heart sound (S2).
During the isometric relaxation phase, all valves are closed, and the ventricles relax.
The volume of blood remaining in the ventricles at this stage is known as the end-systolic volume (ESV), typically around 50 ml.
The aortic dicrotic notch coincides with the closure of the aortic valve.
Continued ventricular relaxation further reduces pressure, allowing the opening of the AV valves.
Ventricles fill passively with blood, accounting for 70% of the end-diastolic volume (EDV).
This passive filling produces the third heart sound (S3).
As blood flows into the ventricles, atrial pressure decreases.

Atrial Systole & Diastole

Atrial diastole occurs throughout most of the cardiac cycle, allowing for venous return.
During atrial systole, the atria contract, completing ventricular filling and contributing 25-30% of the EDV, which typically reaches 120 ml.
Atrial contraction increases atrial pressure, generating a wave on the pressure tracing (a wave).
In hypertensive patients, atrial systole can produce the fourth heart sound (S4), although it is usually inaudible.

New Cardiac Cycle

As ventricular systole begins, ventricular pressure rises above atrial pressure, leading to the closure of the AV valves.
This initiates a new cardiac cycle, with the process repeating itself.

Pressure Volume Curve

The pressure-volume curve visually represents the relationships between ventricular pressure and volume throughout the cardiac cycle.

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Description

Test your knowledge on the anatomy and branches of the right and left coronary arteries. This quiz will cover their origins, pathways, and major branches. Perfect for students in cardiovascular studies or anyone interested in heart anatomy.