Heart Anatomy and Pericardial Sinuses

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Questions and Answers

Which opening of the right atrium is not guarded by a valve?

Right atrioventricular orifice

Coronary sinus

Inferior vena cava

Superior vena cava (correct)

What term is used to describe the funnel-shaped part of the right ventricle as it approaches the pulmonary orifice?

Conus arteriosus (correct)

Trabeculae carnae

Chordae tendinae

Moderatory band

What connects the papillary muscles to the cusps of the tricuspid valve?

Chordae tendinae (correct)

Pulmonary orifice

Moderator band

Trabeculae carnae

What structure provides attachment for the tricuspid valve?

Fibrous ring around the right atrioventricular orifice Signup and view all the answers

Which muscle projections are specifically found in the wall of the right ventricle?

Papillary muscles Signup and view all the answers

What shape is the heart described as having?

Pyramidal Signup and view all the answers

Which chamber of the heart is responsible for pumping blood into the pulmonary trunk?

Right ventricle Signup and view all the answers

What structure surrounds the heart?

Pericardium Signup and view all the answers

Which orifice is known as the left atrioventricular orifice?

Mitral orifice Signup and view all the answers

Which part of the heart is directed downwards, forwards and to the left?

Apex Signup and view all the answers

What is the main function of the atria in the heart?

Receive blood Signup and view all the answers

What is the Transverse Sinus located between?

Ascending aorta and pulmonary trunk Signup and view all the answers

Which part of the heart is formed by the left ventricle?

Apex Signup and view all the answers

What structures separate the heart from the vertebral column?

Descending aorta, esophagus, and oblique sinus of pericardium Signup and view all the answers

Which part of the heart is formed mainly by the left ventricle?

Left border Signup and view all the answers

What feature is created by the crista terminalis within the right atrium?

Trabeculated muscle bundles Signup and view all the answers

What is the function of the tricuspid valve in the heart?

To allow blood to pass from the right atrium to the right ventricle Signup and view all the answers

What is the anatomical position of the right atrium in relation to the left atrium?

Anterior Signup and view all the answers

Which part of the right atrium is smooth in texture?

Sinus venarum Signup and view all the answers

What marks the margin of the fossa ovalis in the interatrial septum?

Anulus ovalis Signup and view all the answers

What is primarily located at the lower border of the heart?

Right ventricle and apical part of left ventricle Signup and view all the answers

What is the primary function of the orifices in the heart?

To allow unidirectional blood flow Signup and view all the answers

Which valve is found between the left atrium and left ventricle?

Bicuspid valve Signup and view all the answers

How many cusps does the tricuspid valve have?

Three Signup and view all the answers

What is the role of the fibrous ring surrounding the heart orifices?

It maintains the shape of the opening Signup and view all the answers

Which of the following valves is formed by three semilunar cusps?

Pulmonary valve Signup and view all the answers

What is unique about the cusps of the pulmonary valve compared to other heart valves?

They have no chordae tendinae or papillary muscles Signup and view all the answers

Which valve is associated with the orifice leading to the aorta?

Aortic valve Signup and view all the answers

What term describes the valves located between the atrium and ventricle?

Atrioventricular valves Signup and view all the answers

What structure guards the left atrioventricular orifice?

Mitral valve Signup and view all the answers

Which chamber of the heart has a thicker wall than the other chambers?

Left ventricle Signup and view all the answers

What type of muscle is found within the wall of the left ventricle?

Trabeculae carnae Signup and view all the answers

What does the left ventricle send blood to?

Ascending aorta Signup and view all the answers

Which nerve supply slows the heart rate?

Vagus nerve Signup and view all the answers

What type of valve is the aortic valve composed of?

Semilunar cusps Signup and view all the answers

What structure receives blood from the left atrium?

Left atrioventricular orifice Signup and view all the answers

Where do postganglionic fibers reach the heart from?

Cardiac plexus Signup and view all the answers

Study Notes

Heart Anatomy

The heart is located in the middle mediastinum.
It is made up of four chambers: two atria and two ventricles.
The atria receive blood, and the ventricles pump blood.
The heart is pyramidal in shape, with an apex, sternocostal surface, diaphragmatic surface, and base.
The heart is surrounded by the pericardium, a fibroserous sac with an outer fibrous layer and an inner serous layer.

Pericardial Sinuses

The serous pericardium has two sinuses: the transverse sinus and the oblique sinus.
The transverse sinus is located between the ascending aorta and pulmonary trunk anteriorly, and the superior vena cava posteriorly.
The oblique sinus lies behind the base of the heart, separating the base from the descending aorta and esophagus.

Apex of the Heart

The apex of the heart is directed downwards, forwards, and to the left.
It is formed by the left ventricle.
The apex is separated from the vertebral column by the descending aorta, esophagus, and the oblique sinus of the pericardium.

Borders of the Heart

The upper border is formed by the two atria.
The right border is formed by the right atrium.
The left border is formed by the left ventricle and the auricle of the left atrium.
The lower border is formed by the right ventricle and the apical part of the left ventricle.

Chambers of the Heart

The heart is divided into four chambers by vertical septa: right atrium, right ventricle, left atrium, and left ventricle.
The right atrium lies anterior to the left atrium, and the right ventricle lies anterior to the left ventricle.

Right Atrium

The right atrium consists of a main cavity and a small outpouching called the auricle.
The sulcus terminalis, a vertical groove on the outside of the heart, forms the crista terminalis on the inside.
The crista terminalis divides the right atrium into an anterior rough part and a posterior smooth part called the sinus venarum.

Cavity of Right Atrium

The interatrial septum contains an oval depression called the fossa ovalis.
The margin of the fossa ovalis is called the anulus ovalis.
Blood leaves the right atrium and enters the right ventricle through the tricuspid valve.

Right Atrium Openings

The superior vena cava (SVC) has no valve.
The inferior vena cava (IVC) is guarded by a valve.
The coronary sinus has a well-defined valve.
The right atrioventricular orifice lies anterior to the IVC opening and is surrounded by a fibrous ring to which the tricuspid valve is attached.
There are also small orifices for small veins.

Cavity of Right Ventricle

The right ventricle's wall is thinner than the left ventricle's wall.
Its wall contains projections called trabeculae carnae.
The right ventricle communicates with the right atrium through the right atrioventricular orifice and with the pulmonary trunk through the pulmonary orifice.
The funnel-shaped part of the cavity near the pulmonary orifice is called the infundibulum or conus arteriosus.
The right ventricle contains three papillary muscles: anterior, posterior, and septal.

Right Ventricle: Papillary Muscles

Each papillary muscle is attached to the cusps of the tricuspid valve by chordae tendinae.
Blood leaves the right ventricle through the pulmonary orifice.
The wall of the infundibulum is smooth and contains no trabeculae carnae.
The interventricular septum is connected to the anterior papillary muscle by a muscular band called the moderator band.

Heart Orifices

Orifices refer to openings in the heart.
There are four main orifices in the heart:
- Two between the atrium and ventricle (atrioventricular).
- Two between the ventricle and the major arteries.

Atrioventricular Orifices

The right atrioventricular orifice is guarded by the tricuspid valve.
The left atrioventricular orifice is guarded by the bicuspid (mitral) valve.
The valves are named tri/bicuspid based on the number of cusps (leaflets).

Ventricular Arterial Orifices

The right ventricle and pulmonary trunk are connected by the pulmonary valve.
The left ventricle and ascending aorta are connected by the aortic valve.
The pulmonary and aortic valves are also called semilunar valves.

Right Atrioventricular (Tricuspid) Orifice

The tricuspid orifice is about one inch wide.
It is guarded by a fibrous ring to which the cusps of the tricuspid valve are attached.
The tricuspid valve has three cusps: anterior, posterior, and septal (medial).
The atrial surfaces of the cusps are smooth, while the ventricular surfaces give attachment to the chordae tendinae.

Pulmonary Orifice

The pulmonary orifice is surrounded by a fibrous ring to which the cusps of the pulmonary valve are attached.
The pulmonary valve has three semilunar cusps: two anterior and one posterior.
The cusps are concave superiorly and convex inferiorly.
There are no chordae tendineae or papillary muscles attached to the cusps.

Left Atrium

The left atrium connects to the left ventricle through the left atrioventricular orifice.
It forms the greater part of the base of the heart.
Its wall is smooth except for small musculi pectinati in the left auricle.
The left atrium receives four pulmonary veins (two left and two right) which have no valves.
Blood is sent to the left ventricle through the left atrioventricular orifice, guarded by the mitral valve (bicuspid valve).

Left Ventricle

The left ventricle wall is thicker than the right ventricle wall.
It receives blood from the left atrium through the left atrioventricular orifice guarded by the mitral valve.
Blood leaves the left ventricle to the ascending aorta through the aortic orifice.
The part of the left ventricle leading to the ascending aorta is called the aortic vestibule.
The aortic vestibule has a fibrous and smooth wall.
The left ventricle contains trabeculae carnae and two large papillary muscles: anterior and posterior.
The papillary muscles are attached by chordae tendinae to the cusps of the mitral valve.

Left Atrioventricular (Mitral) Orifice

The mitral orifice is smaller than the right atrioventricular orifice.
It is guarded by the mitral valve.
It is surrounded by a fibrous ring to which the cusps of the mitral valve are attached.
The mitral valve has two cusps: an anterior cusp and a posterior cusp.
The atrial surfaces of the cusps are smooth, while the ventricular surfaces give attachment to the chordae tendinae.

Aortic Orifice

The aortic orifice is surrounded by a fibrous ring that attaches to the cusps of the aortic valve.
The aortic valve is formed by three semilunar cusps, similar to the pulmonary valve, but the positions of the cusps are different: one anterior and two posterior..

Nerve Supply of the Heart

The heart receives autonomic nerve supply through the cardiac plexus located below the aortic arch.
The sympathetic fibers originate from the cervical and upper thoracic ganglia (1, 2, 3, 4) of the sympathetic trunks.
The parasympathetic fibers originate from the vagus nerves.
Sympathetic fibers accelerate heart rate.
Parasympathetic fibers slow heart rate and constrict coronary arteries.
Postganglionic fibers reach the heart through the sinoatrial node (SAN), atrioventricular node (AVN), and the nerve plexus around the coronary arteries.

Conduction System of the Heart

The beating of the heart is regulated by the intrinsic conduction (nodal) system.

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Description

Explore the intricate structures of the heart, including its four chambers and the surrounding pericardial sinuses. This quiz covers key anatomical features such as the apex of the heart and the relationship of the heart to surrounding organs. Test your knowledge on heart anatomy and its functions.