30 Questions
Which structure is responsible for initiating and regulating impulses for contraction of the four chambers of the heart?
SA node
Where is the AV node located in the heart?
In the posteroinferior region of interatrial septum
Which part of the heart's conduction system passes through the wall of the right atrium by myocardial conduction?
SA node
What is the main function of the AV node's timing delay of 0.1 seconds?
To allow completion of atrial contraction before ventricles contract
Which autonomic nerve fibers supply the heart from deep and superficial cardiac plexuses?
Sympathetic fibers
Which branch of the autonomic nervous system is active during 'Rest and Digest' periods?
Parasympathetic nervous system
Which part of the heart receives autonomic nerve fibers from both sympathetic and parasympathetic systems?
SA node
Which part of the heart's conduction system innervates the muscle of the interventricular septum?
AV bundles
Where do the right subendocardial branches travel in order to stimulate the right papillary muscle and right ventricle?
Through the septomarginal trabecula
What is the main role of sympathetic supply to the heart during periods of intense activities?
Increase heart rate, contractile force, and blood pressure
Which layer of the pericardium is continuous with the central tendon of the diaphragm?
Fibrous pericardium
What is the function of the small amount of serous fluid in the pericardial cavity?
To minimize friction when the heart beats
Which artery primarily supplies the right atria and most of the right ventricle?
Right coronary artery (RCA)
What is responsible for preventing backflow of blood into the right atrium?
Tricuspid valve
Where is the SA node located in some individuals?
Left coronary artery (LCA)
What separates the right and left ventricles and carries specialized fibers such as the bundle branches?
Interventricular septum
Which chamber of the heart receives deoxygenated blood?
Right atrium
Where does the heart primarily drain into?
Coronary sinus
Which layer of the heart is mainly responsible for contracting and pumping blood?
Myocardium
What is located at the right atrioventricular orifice that prevents backflow of blood into the atrium?
Tricuspid valve
Which structure contains the thoracic viscera except lungs?
Mediastinum
What extends from the thoracic aperture to the sternal angle and the IV disc between T4 and T5?
Superior mediastinum
Which structure is located in the middle mediastinum?
Ascending aorta
In infants, which structure is contained in the anterior mediastinum?
Thymus gland
What structure lies in the posterior mediastinum?
Thoracic duct
Which layer of the heart is outermost and primarily composed of dense connective tissue?
Fibrous pericardium
Which nerve is not a component of the contents of the superior mediastinum?
Phrenic nerve
Which vessel is not found in the middle mediastinum?
Thoracic duct
What extends from the thoracic aperture to the floor of diaphragm?
Inferior mediastinum
Which structure forms part of the anterior mediastinum?
Thymus gland
Study Notes
- The pericardium is a tough, protective sac surrounding the heart. It is continuous with the central tendon of the diaphragm.
- The pericardium consists of two layers: the fibrous pericardium and the serous pericardium. The serous pericardium has two divisions: the parietal and the visceral serous layers.
- The pericardial cavity, located between the fibrous and serous pericardium, contains a small amount of serous fluid that minimizes friction when the heart beats.
- The heart is made up of three layers: the epicardium, myocardium, and endocardium. The heart is mainly supplied by the pericardiacophrenic artery and drains primarily into the pericardiacophrenic veins.
- The heart is located in the oblique plane, with two-thirds of it on the left side. It is oriented with the base toward the right shoulder and the apex toward the left hip.
- The heart has two atria (right and left) and two ventricles (right and left). The right atrium is where deoxygenated blood returns to the heart, and it has an opening (right atrioventricular orifice) leading to the right ventricle.
- The tricuspid valve, located at the right atrioventricular orifice, has three cusps and is responsible for preventing backflow of blood into the atrium. The right ventricle has irregular muscular elevations called trabeculae carneae and pushes blood to the lungs through the pulmonary valve.
- The interventricular septum separates the right and left ventricles and carries the atrioventricular bundles, bundle branches, and ultimately the right bundle branch to the right ventricle. The heart is supplied by two main coronary arteries: the right coronary artery (RCA) and the left coronary artery (LCA). The RCA supplies the right atria, most of the right ventricle, some of the left ventricle, and the IV septum, while the LCA supplies the left atrium, most of the left ventricle, most of the IV septum, some of the right ventricle, and the SA node in some individuals. The heart's venous drainage is primarily through the coronary sinus, which receives blood from the great cardiac vein and small cardiac veins, among others. The conducting system of the heart is responsible for initiating and conducting electrical impulses and is made up of specialized fibers, including the SA node, which acts as the pacemaker of the heart.
Test your knowledge of the anatomy of the mediastinum, the region in the middle of the chest that contains all thoracic viscera except lungs. Learn about its divisions, boundaries, and contents.
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