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Pulmonary Valve

At the apex of the infundibulum (conus arteriosus), the opening into the pulmonary trunk is closed by the pulmonary valve.

Structure: 3 semilunar cusps with free edges projecting upward into the lumen of the pulmonary trunk. The free superior edge of each cusp has a nodule thickened portion, the lunula thin lateral portion, and a left, right, anterior of the semilunar cusp.

The cusps are named the free superior edge middle and semilunar cusps.

Mechanism:

1. The semilunar valves open when pressure in the ventricles exceeds the pressure in the arteries, permitting ejection of blood from the ventricles into the pulmonary trunk and aorta.
2. When the blood flows back, it fills the valve cusps, which causes the free edges of semilunar valves to contact each other tightly and close the opening between the ventricle and artery.

Left Atrium

The left atrium forms most of the base of the heart. The volume is smaller than the right atrium but it has a thicker wall.

The interatrial septum is part of the.

VENTRICLE

The left ventricle is constructed in accordance with its role as a powerful pump for the high-pressure systemic arterial circulation. It is longer and narrower than the right ventricle, extending from its base in the plane of the atrioventricular sulcus to the cardiac apex. Except where obscured by the ascending aorta and base of the ventricular cone, the left ventricle is superficially separated from the left atrium by part of the atrioventricular sulcus with the coronary sinus passing along its posterior and inferior aspects.

The left ventricle has an inlet part guarded by the mitral (left atrioventricular) valve, and an outlet part guarded by the aortic valve. During diastole, the left atrioventricular orifice admits left atrial blood with the flow being directed towards the cardiac apex. After closure of the mitral valvular leaflets (cusps) and throughout the ejection phase of systole, blood is expelled from the cardiac apex through the aortic orifice.

MITRAL (LEFT ATRIOVENTRICULAR/BICUSPID) VALVE

The general

Description of the component parts of the tricuspid valve also applies to the mitral valve; it has an orifice with a supporting annulus, valvular leaflets and varying arrangements of chordae tendineae and papillary muscles.

Mitral valvular orifice

The mitral valvular orifice, smaller than the tricuspid orifice, is a well-defined transitional zone between the left atrial wall and the inserted margin of the mitral valvular leaflets bases.

Anulus not a simple fibrous

The ring of the valve is not a simple fibrous ring but is made up of elements of varying consistency, from which the fibrous core of each leaflet takes origin.

The area of the annulus increases linearly with body surface area in children and young adults.

Mitral valvular leaflets two cusps:

The mitral valvular leaflets have long been described as paired structures; it has the anterior and posterior cusps.

At their base, the cusps are secured to a surrounding fibrous ring.

AORTIC ROOT anatomical bridge

The aortic root, the anatomical bridge between the left ventricle and ascending aorta,

consists of aortic valvular leaflets supported by the sinuses (of Valsalva) and the inter-leaflet triangles basal attachments. Interposed between their Pagina 8 di 13 fi fl fi fi fi fi fl fl fl fl fl fi fi fi fi fl fi fi fl fi fl

AORTIC VALVE

Outflow tract of the left ventricle, is continuous superiorly with the ascending aorta. The opening from the left ventricle into the aorta is closed by the valve. It consists of three semilunar cusps with the free edge upward of each projecting into the lumen of the ascending aorta. Between the semilunar cusps and the wall of the right, ascending aorta are pocket-like sinuses—the left, and posterior aortic sinuses. The right and left coronary arteries originate from the right and left aortic sinuses.

CARDIAC SKELETON

ANULUS FIBROUSUS: dense, fibrous connective tissue forming four rings between the atria and the ventricles. It surrounds the two atrioventricular orifices, the aortic orifice and opening of the pulmonary trunk. right fibrous trigone, and left

• the sinuatrial node
• the atrioventricular node
• the atrioventricular bundle (of His) including the right and left bundle branches
• the subendocardial plexus of conduction cells (the Purkinje bers)

atrio-ventricular septum

It follows the lower border of the membranous part of the interventricular septum before splitting into right and left bundles.

THE RIGHT BUNDLE BRANCH interventricular septum

The right bundle branch continues on the right side of the toward the apex of the right ventricle.

septomarginal trabecula

From the septum it enters the to reach the base of the anterior papillary muscle. It divides and is continuous with the final component of the Purkinje Fibers cardiac conduction system the (or subendocardial branches).

THE LEFT BUNDLE BRANCH muscular interventricular septum

The left bundle branch passes to the left side of the and apex of the left ventricle. It descends to the It spreads the excitation impulses throughout the ventricle.

CORONARY VASCULATURE

ARTERIES: Two coronary arteries arise from the aortic sinuses in the initial portion of the ascending aorta and supply the muscle and other tissues of the heart. They circle the heart in the coronary sulcus.

VEINS: The returning venous

1. The blood from the cardiac veins passes through and empties into the coronary sinus.
2. The right coronary artery (RCA) branches off the ascending aorta, turns to the right, and passes between the right auricle and the pulmonary trunk. It then descends between the right atrium and right ventricle in the coronary sulcus.
3. The right coronary artery supplies blood to the right atrium, the interatrial septum, the right ventricle, and portions of the conducting system of the heart.
4. The branches of the right coronary artery include:
1. Atrial branch passing between the right auricle and ascending aorta
2. Right marginal branch located in the inferior (acute) margin of the heart
3. Branch to the atrioventricular node
4. Posterior interventricular branch located in the posterior interventricular sulcus
5. The left coronary artery branches originate from the left aortic sinus of the ascending aorta, passing between the pulmonary trunk and the left auricle, and enter the coronary sulcus. The artery divides into its two terminal branches:
1. Anterior interventricular branch
2. Circumflex branch

1. The left side of the pulmonary trunk and descends obliquely toward the apex of the heart in the anterior interventricular sulcus.
2. The circumflex artery continues to the left in the coronary sulcus and onto the diaphragmatic surface of the heart.
3. Blood supply: most of the left ventricle, small portion of the right ventricle, most of the left atrium, and the anterior two-thirds of the interventricular septum.

CARDIAC VEINS

The coronary sinus receives four tributaries: great, middle, small, and inferior cardiac veins.

• The great cardiac vein begins at the apex of the heart and ascends in the anterior interventricular sulcus, where it travels with the anterior interventricular artery.
• In the coronary sulcus, the great cardiac vein enlarges becoming the coronary sinus, which enters the right atrium.
• The middle cardiac vein begins near the apex of the heart and ascends in the posterior interventricular sulcus toward the coronary sinus.
• The small cardiac vein begins in the lower anterior.

  The coronary sulcus is located between the right atrium and right ventricle.

  The inferior cardiac vein lies on the posterior surface of the left ventricle.

  Pulmonary Trunk

  The pulmonary trunk is covered by the visceral layer of serous pericardium. It arises from the conus arteriosus of the right ventricle.

  It is located anterior to the aortic orifice and ascends to the left.

  The pulmonary arteries carry deoxygenated blood to the lungs from the right ventricle of the heart.

  It divides into:

  • Right pulmonary artery: passes posterior to the ascending aorta and the superior vena cava to enter the right lung. It enters the root of the lung and gives off a large branch to the superior lobe of the lung, a second (recurrent) branch to the superior lobe, and then divides to supply the middle and inferior lobes.
  • Left pulmonary artery: passes inferiorly to the arch of the aorta and anteriorly to the descending aorta to enter the left lung.

  Pulmonary Veins

  The superior and inferior pulmonary veins carry oxygenated blood.

  Blood from the lungs is transported back to the heart through the veins. The veins start at the hilum of the lung, pass through the root of the lung, and directly drain into the left atrium.