Pericardium and Anatomy of the Heart

Vocabulary practice flashcards covering pericardial anatomy, heart chambers, external features, cardiac valves, coronary circulation, conducting system, and clinical correlations.

Pericardium

A fibroserous membrane located in the middle mediastinum that encloses the heart and the proximal portions of its great vessels; consists of an outer tough fibrous pericardium and an inner serous pericardium.

Pericardial Cavity

A potential space between the parietal and visceral layers of the serous pericardium that contains a thin film of serous fluid, providing a frictionless environment for cardiac movement.

Transverse Pericardial Sinus

A transversely oriented passage within the pericardial cavity situated posterior to the ascending aorta and pulmonary trunk, and anterior to the superior vena cava; clinically used to place a surgical clamp or ligature during cardiac procedures such as coronary artery bypass grafting.

Oblique Pericardial Sinus

A blind recess (cul-de-sac) in the pericardial cavity located posterior to the left atrium, bounded by the inverted "J"-shaped reflection of serous pericardium surrounding the pulmonary veins and inferior vena cava.

Pericardiacophrenic Artery

The primary arterial supply to the pericardium, originating as a branch of the internal thoracic artery.

Pericardiacophrenic Veins

Tributaries draining pericardial venous blood into the brachiocephalic veins or internal thoracic veins.

Phrenic Nerves ($C3-C5$)

Nerves providing sensory innervation to the fibrous pericardium and the parietal layer of the serous pericardium; their stimulation accounts for referred pain to the ipsilateral supraclavicular region ($C3-C5$ dermatomes).

Pericarditis

Inflammation of the pericardium that characteristically presents with chest pain and a pericardial friction rub audible on auscultation.

Pericardial Effusion

The abnormal accumulation of excess fluid within the pericardial cavity between the parietal and visceral layers of the serous pericardium.

Cardiac Tamponade

Compression of the heart caused by rapid or extensive fluid accumulation in the pericardial cavity; the inelastic fibrous pericardium restricts expansion, leading to decreased cardiac output and elevated systemic venous pressure.

Pericardiocentesis

The aspiration of fluid from the pericardial cavity using a wide-bore needle typically inserted through the left infrasternal (subcostal/costoxiphoid) angle angled superiorly, or via the left 5th or 6th intercostal space near the sternum.

Endocardium

The thin innermost endothelial and subendothelial connective tissue layer of the heart wall that lines the chambers and covers the cardiac valves.

Myocardium

The thick, middle, helically arranged contractile layer of the heart wall composed of highly vascularized cardiac muscle tissue.

Epicardium

The thin external mesothelial layer of the heart wall, formed by the visceral layer of the serous pericardium.

Apex of the Heart

The inferolateral tip of the heart formed exclusively by the left ventricle, situated at the left 5th intercostal space approximately $9\,\text{cm}$ from the midsternal line in the midclavicular line; site of the maximal apex beat.

Base of the Heart

The posterior aspect of the heart, formed mainly by the left atrium, a small portion of the right atrium, the pulmonary veins, superior vena cava, and inferior vena cava.

Pectinate Muscles

Prominent parallel ridges of muscular tissue lining the interior of the muscular auricles and the anterior wall of the right atrium.

Crista Terminalis

An internal vertical muscular ridge in the right atrium that demarcates the smooth posterior sinus venarum from the rough anterior pectinate muscle wall; its superior extent marks the site of the sinoatrial node.

Fossa Ovalis

An oval depression on the right atrial aspect of the interatrial septum, representing the remnant of the fetal foramen ovale and its valve.

Trabeculae Carneae

Irregular muscular elevations and ridges projecting from the internal myocardial wall of the cardiac ventricles.

Papillary Muscles

Cone-shaped projections of trabeculae carneae arising from the ventricular walls that contract prior to ventricular systole to tighten chordae tendineae and prevent atrioventricular valve leaflet prolapse.

Chordae Tendineae

Fibrous, tendon-like cords connecting papillary muscle apices to the free edges and ventricular surfaces of atrioventricular valve cusps.

Moderator Band (Septomarginal Trabecula)

A curved muscular bundle spanning from the lower interventricular septum to the base of the anterior papillary muscle in the right ventricle; conveys the right branch of the atrioventricular bundle.

First Heart Sound ($S_1$)

The acoustic sound caused by the mechanical closure of the atrioventricular valves (mitral and tricuspid) at the beginning of ventricular systole.

Second Heart Sound ($S_2$)

The acoustic sound produced by the closure of the semilunar valves (aortic and pulmonary) at the end of ventricular systole and the onset of diastole.

Aortic Valve Auscultation Site

The clinical listening point for the aortic valve located at the right 2nd intercostal space, adjacent to the sternal border.

Pulmonary Valve Auscultation Site

The clinical listening point for the pulmonary valve located at the left 2nd intercostal space, adjacent to the sternal border.

Tricuspid Valve Auscultation Site

The clinical listening point for the tricuspid valve located at the left 5th intercostal space at the sternal border.

Mitral Valve Auscultation Site

The clinical listening point for the mitral valve located at the left 5th intercostal space in the midclavicular line (apex beat).

Right Coronary Artery (RCA)

Artery originating from the right aortic sinus of the ascending aorta; typically supplies the right atrium, most of the right ventricle, the diaphragmatic surface of the left ventricle, the posterior third of the interventricular septum, the SA node (in approximately $60\%$ of individuals), and the AV node (in approximately $80\%$ of individuals).

Left Anterior Descending (LAD) Artery

The anterior interventricular branch of the left coronary artery; supplies the anterior two-thirds of the interventricular septum, adjacent ventricles, and the atrioventricular bundle, and represents the most frequently occluded artery in myocardial infarction ($40\%-50\%$ of cases).

Coronary Sinus

The wide venous channel located in the posterior coronary sulcus that receives the majority of the cardiac veins and discharges blood directly into the right atrium.

Great Cardiac Vein

The principal tributary of the coronary sinus that ascends in the anterior interventricular groove alongside the left anterior descending (anterior interventricular) artery.

Middle Cardiac Vein

A venous tributary that runs in the posterior interventricular groove alongside the posterior interventricular (posterior descending) artery before entering the coronary sinus.

Sinoatrial (SA) Node

The cardiac pacemaker composed of specialized conducting myocardium, situated in the anterolateral wall of the right atrium at the superior junction of the crista terminalis and superior vena cava.

Atrioventricular (AV) Node

A group of specialized conducting cells located in the posteroinferior part of the interatrial septum, between the opening of the coronary sinus and the septal cusp of the tricuspid valve.

Conducting System of the Heart

Specialized network of modified cardiac muscle cells consisting of the SA node, AV node, atrioventricular bundle of His, right and left bundle branches, and subendocardial Purkinje fibers that coordinates atrial and ventricular contractions.

Purkinje Fibers

Large, pale, modified myocardial cells that form the terminal subendocardial conducting network distributed to the ventricular walls.

Cardiac Sympathetic Innervation

Autonomic input originating from the $T1-T4/T5$ segments of the spinal cord that accelerates heart rate, enhances contractile force, and transmits visceral afferent pain fibers from the heart.

Cardiac Parasympathetic Innervation

Autonomic input conveyed by the vagus nerves ($\text{CN } X$) that reduces heart rate and diminishes atrial contractility.

Angina Pectoris

Transitory substernal chest discomfort or pain provoked by myocardial ischemia secondary to narrowed coronary arteries, radiating to the inner side of the left arm, shoulder, or neck through sympathetic cardiac sensory fibers targeting $T1-T5$ spinal levels.