Anatomy of the Heart

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Questions and Answers

What function do the papillary muscles serve during ventricular contraction?

They increase pressure in the atrium.

They open the AV valves to allow blood flow.

They pull the chordae tendineae to prevent the AV valves from opening into the atrium. (correct)

They assist in closing the semilunar valves.

When do the semilunar valves open?

When the ventricular pressure exceeds arterial pressure. (correct)

During diastole when the heart is at rest.

During ventricular relaxation and blood flow back into the ventricles.

When the atria contract and pressure in the atria exceeds that of the ventricles.

Which vessels return deoxygenated blood to the right atrium?

Pulmonary veins and aorta.

Superior vena cava and inferior vena cava. (correct)

Aorta and pulmonary artery.

Pulmonary artery and pulmonary veins.

What prevents backflow of blood after it has exited the ventricles through the semilunar valves?

The shape of the valves' cusps. Signup and view all the answers

What happens to the AV valves during atrial contraction?

They open due to high pressure in the atrium. Signup and view all the answers

What anatomical structure keeps the heart in place while allowing for vigorous contractions?

Pericardium Signup and view all the answers

Which of the following correctly describes the location of the heart within the mediastinum?

Between the sternum and vertebral column, and between the lungs Signup and view all the answers

Which chamber of the heart primarily forms the base?

Left atrium Signup and view all the answers

What is the approximate size and weight of the human heart?

12 cm long, 9 cm wide, 6 cm thick, 250g Signup and view all the answers

Which part of the pericardium is responsible for anchoring the heart to the mediastinum?

Fibrous part Signup and view all the answers

Which surface of the heart primarily involves the left atrium?

Posterior surface Signup and view all the answers

Which anatomical feature of the heart represents its apex?

Mid clavicular line, 5th intercostal space Signup and view all the answers

What is the structure of the heart primarily related to its function as a double pump?

Four chambers and valves Signup and view all the answers

What is the primary function of pericardial fluid?

To reduce friction between the layers of the pericardium Signup and view all the answers

Which structure separates the right and left atrium?

Fossa ovalis Signup and view all the answers

What are trabeculae carneae?

Muscular ridges within the ventricles Signup and view all the answers

Which valve connects the right atrium to the right ventricle?

Tricuspid valve Signup and view all the answers

Which chamber of the heart has the thickest myocardium?

Left ventricle Signup and view all the answers

What is the primary consequence of pericarditis?

Chest pain mimicking a heart attack Signup and view all the answers

What role does the fibrous skeleton of the heart play?

It provides a site for muscle insertion and insulation between chambers Signup and view all the answers

Which of the following statements about the left atrium is true?

It receives blood from the pulmonary veins Signup and view all the answers

What feature characterizes the right ventricle?

It has a short distance to pump blood to the lungs Signup and view all the answers

What is the role of the mitral valve?

Connecting the left atrium to the left ventricle Signup and view all the answers

Study Notes

Anatomical Location of the Heart

The heart is roughly the size of a closed fist, measuring 12cm long, 9 cm wide, and 6 cm thick.
The heart weighs approximately 250g.
Situated in the mediastinum, between the sternum, vertebral column, first rib, and between the lungs.
Two-thirds of the heart's mass lies to the left of the midline.

Heart Surface Anatomical Markings

Anterior (Sternocostal) Surface: Right atrium and right ventricle.
Inferior (Diaphragmatic) Surface: Right and left ventricles.
Posterior Surface: Predominantly the left atrium.

Borders and Apex

The heart has three borders, forming a pyramidal shape:
- Inferior Border: Right ventricle.
- Left Border: Left ventricle and a portion of the left atrium.
- Right Border: Right atrium.
The apex, the tip of the left ventricle, rests on the diaphragm.
The base is formed by the atria.

Pericardium

The pericardium is the membranous sac surrounding the heart.
It anchors the heart within the mediastinum while allowing for vigorous contractions.
Consists of two parts:
- Fibrous Part: Tough, inelastic connective tissue that connects to the heart and blood vessels. It prevents overstretching.
- Serous Part: Thinner layer, comprising a double layer. The outer parietal layer is attached to the fibrous part, while the inner visceral layer forms the epicardium.

Pericardial Fluid

Between the two layers of the serous pericardium, a lubricating fluid (about 30 ml) reduces friction during heart movement.

Pericarditis

Inflammation of the pericardium.
Can be caused by various factors, including viral, bacterial infections, and radiation.
Characterized by chest pain radiating to the left shoulder and arm.
Often mistaken for a heart attack.
ST elevation across all leads is observed.
Pericardial friction rub: A creaking sound heard with a stethoscope in about 40% of patients.

Muscular Structures of the Heart

The heart wall is composed of three layers:
- Epicardium: The visceral layer of the serous pericardium, containing adipose tissue and blood vessels supplying the myocardium.
- Myocardium: Cardiac striated muscle tissue responsible for heart contraction.
- Endocardium: Smooth inner lining on connective tissue, lining the chambers and valves.

Chambers of the Heart

The heart has four chambers:
- Atria (superior): Increase the heart's capacity.
- Ventricles (inferior): Responsible for pumping blood.
Sulci: Grooves on the heart's surface:
- Coronary Sulcus: Divides the atria from the ventricles.
- Anterior and posterior Interventricular Sulci: Divide the two ventricles.

Right Atrium

Receives blood from the:
- Inferior vena cava
- Superior vena cava
- Coronary sinus
Pectinate muscles: Rough muscular ridges on the anterior wall.
Interatrial septum: A thin wall separating the right and left atrium.
Blood from the right atrium enters the ventricle through the tricuspid valve (3 cusps).

Right Ventricle

Trabeculae carneae: Raised bundles of cardiac muscle fibers.
Chordae tendineae: Tendons connecting to the leaflets of the tricuspid valve.
Papillary muscles: Muscles attached to chordae tendineae.
Interventricular septum: Divides the two ventricles.
Blood exits the heart through the pulmonary valve, entering the pulmonary trunk.

Left Atrium

Receives blood from the four pulmonary veins.
Blood passes from the atrium to the ventricle through the bicuspid (mitral) valve (2 cusps).

Left Vetricle

Similar to the right ventricle, it contains trabeculae carneae, chordae tendinae that anchor the mitral valve cusps to papillary muscles.
Blood exits the ventricle via the aortic valve, entering the ascending aorta.
Coronary arteries and descending aorta originate from the ascending aorta.

Myocardial Thickness

The thickness of the myocardium varies based on the chamber's function:
- Atria: 2-3 mm thick, as they only need to deliver blood to the ventricles.
- Ventricles: Thicker due to their need to pump blood further with higher pressure.
  - Right ventricle: 4-5 mm thick.
  - Left ventricle: 10-15 mm thick, due to its responsibility for pumping blood throughout the body.

Fibrous Skeleton

A dense connective tissue that provides structural support for the heart.
It serves as an insertion point for muscle bundles and acts as an electrical insulator between the atria and ventricles.

Valves of the Heart

Atrioventricular Valves (Tricuspid and Mitral):
- Open during atrial contraction (high pressure): The cusps project into the ventricle.
- Close during ventricular contraction (high pressure): The cusps are pulled upwards and closed.
- Papillary muscles: Contract to prevent cusps from opening into the atrium.
Semilunar Valves (Aortic and Pulmonary):
- Open during ventricular contraction (high pressure): Blood flows into the arteries, and cusps project into the lumen.
- Close during ventricular relaxation (low pressure): Blood flows back, filling the cusps and promoting closure, preventing backflow.

Main Great Vessels

Five great vessels enter and exit the heart:
- Superior vena cava & Inferior vena cava: Carry deoxygenated blood from the body to the right atrium.
- Pulmonary artery: Carries deoxygenated blood from the right ventricle to the lungs (oxygenation).
- Pulmonary veins: Carry oxygenated blood from the lungs to the left atrium.
- Aorta: Carries oxygenated blood from the left ventricle into general circulation.

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Description

Explore the intricate structures and locations of the heart in this quiz. Learn about the heart's size, weight, surfaces, borders, and the surrounding pericardium. Test your knowledge on the essential anatomical details of this vital organ.