Heart Flashcards
innervarion of the pericardium
The phrenic nerve (C3-C5) is responsible for the somatic innervation of the pericardium, as well as providing motor and sensory innervation to the diaphragm. Originating in the neck and travelling down through the thoracic cavity, the phrenic nerve is a common source of referred pain, with a key example being shoulder pain experienced as a result of pericarditis.
functions of the pericardium
Fixes the heart in the mediastinum and limits its motion. Fixation of the heart is possible because the pericardium is attached to the diaphragm, the sternum, and the tunica adventitia (outer layer) of the great vessels
Prevents overfilling of the heart. The relatively inextensible fibrous layer of the pericardium prevents the heart from increasing in size too rapidly, thus placing a physical limit on the potential size of the organ
Lubrication. A thin film of fluid between the two layers of the serous pericardium reduces the friction generated by the heart as it moves within the thoracic cavity
Protection from infection. The fibrous pericardium serves as a physical barrier between the muscular body of the heart and adjacent organs prone to infection, such as the lungs.
layers of the heart Fart Police Smell Villian
F – Fibrous layer of the pericardium
P – Parietal layer of the serous pericardium
S – Serous fluid
V – Visceral layer of the serous pericardium
whar are the two main layers that make up the pericardium
a tough external layer known as the fibrous pericardium, and a thin, internal layer known as the serous pericardium (to overextend the orange metaphor, the outer peel could be thought of as the fibrous layer, with the inner white stuff being the serous layer).
desribe the fibrous pericardium
Continuous with the central tendon of the diaphragm, the fibrous pericardium is made of tough connective tissue and is relatively non-distensible. Its rigid structure prevents rapid overfilling of the heart, but can contribute to serious clinical consequences (see cardiac tamponade).
desribe the seous pericardium
Enclosed within the fibrous pericardium, the serous pericardium is itself divided into two layers: the outer parietal layer that lines the internal surface of the fibrous pericardium and the internal visceral layer that forms the outer layer of the heart (also known as the epicardium). Each layer is made up of a single sheet of epithelial cells, known as mesothelium.
Found between the outer and inner serous layers is the pericardial cavity, which contains a small amount of lubricating serous fluid. The serous fluid serves to minimize the friction generated by the heart as it contracts.
what the pericardium
is a fibroserous, fluid-filled sack that surrounds the muscular body of the heart and the roots of the great vessels (the aorta, pulmonary artery, pulmonary veins, and the superior and inferior vena cavae).
which medisteinum does the heart lie
middle medisteinum
in which direction is the apex of the heart beating
anterior-inferior direction.
5 divisions of the heart
Anterior (or sternocostal) – Right ventricle.
Posterior (or base) – Left atrium.
Inferior (or diaphragmatic) – Left and right ventricles.
Right pulmonary – Right atrium.
Left pulmonary – Left ventricle.
borders of the heart
Right border – Right atrium
Inferior border – Left ventricle and right ventricle
Left border – Left ventricle (and some of the left atrium)
Superior border – Right and left atrium and the great vessel
sulci of the heart
The heart is a hollow structure. On the interior, it is divided into four chambers. These divisions create grooves on the surface of the heart – these are known as sulci.
The coronary sulcus (or atrioventricular groove) runs transversely around the heart – it represents the wall dividing the atria from the ventricles. The sinus contains important vasculature, such as the right coronary artery.
The anterior and posterior interventricular sulci can be found running vertically on their respective sides of the heart. They represent the wall separating the ventricles.
pericardial sinuses
The pericardial sinuses are not the same as ‘anatomical sinuses’ (such as the paranasal sinuses). They are passageways formed the unique way in which the pericardium folds around the great vessels.
The oblique pericardial sinus is a blind ending passageway (‘cul de sac’) located on the posterior surface of the heart.
The transverse pericardial sinus is found superiorly on the heart. It can be used in coronary artery bypass grafting – see below.
briefly desscribe pulmonary circulation
Blood returning to the heart enters the atria, and is then pumped into the ventricles. From the left ventricle, blood passes into the aorta and enters the systemic circulation. From the right, it enters the pulmonary circulation via the pulmonary arteries.
desribe the right atrim
The right atrium receives deoxygenated blood from the superior and inferior vena cavae, and from the coronary veins. It pumps this blood through the right atrioventricular orifice (guarded by the tricuspid valve) into the right ventricle.
In the anatomical position, the right atrium forms the right border of the heart. Extending from the antero-medial portion of the chamber is the right auricle (right atrial appendage) – a muscular pouch that acts to increase the capacity of the atrium.
The interior surface of the right atrium can be divided into two parts, each with a distinct embryological origin. These two parts are separated by a muscular ridge called the crista terminalis:
Sinus venarum – located posterior to the crista terminalis. This part receives blood from the superior and inferior vena cavae. It has smooth walls and is derived from the embryonic sinus venosus.
Atrium proper – located anterior to the crista terminalis, and includes the right auricle. It is derived from the primitive atrium, and has rough, muscular walls formed by pectinate muscles.
The coronary sinus receives blood from the coronary veins. It opens into the right atrium between the inferior vena cava orifice and the right atrioventricular orifice.
desribe the intratrial septum
The interatrial septum is a solid muscular wall that separates the right and left atria.
The septal wall in the right atrium is marked by a small oval-shaped depression called the fossa ovalis. This is the remnant of the foramen ovale in the foetal heart, which allows right to left shunting of blood to bypass the lungs. It closes once the newborn takes its first breath.
dssribe the left atrium
The left atrium receives oxygenated blood from the four pulmonary veins, and pumps it through the left atrioventricular orifice (guarded by the mitral valve) into the left ventricle.
In the anatomical position, the left atrium forms the posterior border (base) of the heart. The left auricle extends from the superior aspect of the chamber, overlapping the root of the pulmonary trunk.
The interior surface of the left atrium can be divided into two parts, each with a distinct embryological origin:
Inflow portion – receives blood from the pulmonary veins. Its internal surface is smooth and it is derived from the pulmonary veins themselves.
Outflow portion – located anteriorly, and includes the left auricle. It is lined by pectinate muscles, and is derived from the embryonic atrium.
where do teh eft and right ventricles of the heart receive blood from, then what do they do with it
the atria and pump it into the outflow vessels; the aorta and the pulmonary artery respectively.
desribe the right ventricle
orifice (guarded by the pulmonary valve), into the pulmonary artery.
It is triangular in shape, and forms the majority of the anterior border of the heart. The right ventricle can be divided into an inflow and outflow portion, which are separated by a muscular ridge known as the supraventricular crest.
Inflow Portion
The interior of the inflow part of the right ventricle is covered by a series of irregular muscular elevations, called trabeculae carnae. They give the ventricle a ‘sponge-like’ appearance, and can be grouped into three main types:
Ridges – attached along their entire length on one side to form ridges along the interior surface of the ventricle. Bridges – attached to the ventricle at both ends, but free in the middle. The most important example of this type is the moderator band, which spans between the interventricular septum and the anterior wall of the right ventricle. It has an important conductive function, containing the right bundle branches. Pillars (papillary muscles) – anchored by their base to the ventricles. Their apices are attached to fibrous cords (chordae tendineae), which are in turn attached to the three tricuspid valve cusps. By contracting, the papillary muscles ‘pull’ on the chordae tendineae to prevent prolapse of the valve leaflets during ventricular systole. Outflow Portion (Conus arteriosus)
The outflow portion (leading to the pulmonary artery) is located in the superior aspect of the ventricle. It is derived from the embryonic bulbus cordis. It is visibly different from the rest of the right ventricle, with smooth walls and no trabeculae carneae.
desribe the interventricular septum
The interventricular septum separates the two ventricles, and is composed of a superior membranous part and an inferior muscular part.
The muscular part forms the majority of the septum and is the same thickness as the left ventricular wall. The membranous part is thinner, and part of the fibrous skeleton of the heart.
desribe the left ventricle
The left ventricle receives oxygenated blood from the left atrium, and pumps it through the aortic orifice (guarded by the aortic valve) into the aorta.
In the anatomical position, the left ventricle forms the apex of the heart, as well as the left and diaphragmatic borders. Much like the right ventricle, it can be divided into an inflow portion and an outflow portion.
Inflow Portion
The walls of the inflow portion of the left ventricle are lined by trabeculae carneae, as described with the right ventricle. There are two papillary muscles present which attach to the cusps of the mitral valve.
Outflow Portion
The outflow part of the left ventricle is known as the aortic vestibule. It is smooth-walled with no trabeculae carneae, and is a derivative of the embryonic bulbus cordis.
