University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2020
Views:

203

Pages:

22
Author:

Jerynclessyncpa6

Valves of the heart Two atrioventricular valves Right atrioventricular or tricuspid valve Left atrioventricular or bicuspid valve Mitral valve Two semilunar valves Aortic valve Pulmonary valve RIGHT ATRIOVENTRICULAR VALVE The TRICUSPID valve so-named because it usually consists of three cusps or leaflets The bases of the valve cusps are attached to the fibrous ring around the orifice annulus fibrosus  Its orifice is best seen from the atrial aspect and measures on average 11.4 cm  The fibrous ring keeps the caliber of the orifice constant (large enough to admit the tips of three fingers)  It is almost VERTICAL!!!!!!!!, but at 45° to the sagittal plane  The atrial surface of the AV valve is rather smooth.  The ventricular surface is irregular because of the insertion of the chordae tendineae 2 The atrioventricular valvular complex Consists of : 1-The orifice and its associated anulus 2- The cusps, the supporting chordae tendineae of various types and the papillary muscles The Tricuspid Valve consists of three cusps Anterior cusp lies anteriorly Septal cusp lies against the ventricular septum inferior (posterior) cusp lies inferiorly  The bases of the cusps are attached to the fibrous ring of the skeleton of the heart whereas their free edges and ventricular surfaces are attached to the  The chordae tendineae connect the cusps to the papillary muscles chordae tendineae. 6 The Tricuspid Valve The cusps The chordae tendineae. papillary muscles 7 Valves Cusps are composed of connective tissue with over-lying endocardium. Each valve is composed of three layers The spongiosa is loose connective tissue located on the atrial or blood vessel side (aortic and pulmonary) of each valve. The ﬁbrosa forms the core of the valve and contains fibrous extensions from the dense irregular connective tissue of the skeletal rings of the heart The ventricularis is immediately adjacent to the ventricular surface of each valve and is covered with endothelium. It contains dense connective tissue with many layers of elastic fibers. In the AV valves, the ventricularis continues into the chordae tendineae Valve cusps are normally avascular Small blood vessels and smooth muscle can be found only in the base of the cusp. The surfaces of the valve are exposed to blood, and the cusps are thin enough to allow nutrients and oxygen to diffuse from the blood (valvulitis).  Rheumatic fever causes inﬂammation of the heart valves (valvulitis)  Inﬂammation induces angiogenesis in the valve and vascularization in the normally avascular layers of the valve.  These changes most commonly affect the mitral valve (65% to 70%) ????!! and aortic valve (20% to 25%).  This inﬂammation can lead to progressive replacement of elastic tissue by irregular masses of collagen ﬁbers, causing the valve to thicken.  The valves become rigid and inﬂexible, which affects their ability to open and close The extreme edges of the cusps are thin and delicate with a sawtooth appearance from the insertion of chordae Away from the edge, the atrial surface of the cusps is finely nodular, the nodule particularly in small children. These nodules are called The noduli Albin The noduli Albini minute fibrous nodules on the margins of the mitral and tricuspid valves of the heart When the ventricle contracts, the papillary muscles contract and prevent the cusps from being forced into the atrium and turning inside out as the intraventricular pressure rises To assist in this process, the chordae tendineae of one papillary muscle are connected to the adjacent parts of two cusps On closure of an AV valve, the narrow border between the row of Albini nodules and the free edge of each cusp presses against that of the next, resulting in a secure, watertight closure 12 Chordae tendineae (tendinous cords) are fibrous collagenous structures supporting the cusps of the atrioventricular valves Tendinous cords attach to the free edges and ventricular surfaces of the anterior, posterior, and septal cusps, much like the cords attaching to a parachute The tendinous cords arise from the apices of papillary muscles 14 Papillary muscles begin to contract before contraction of the right ventricle, tightening the tendinous cords and drawing the cusps together. Because the cords are attached to adjacent sides of two cusps, they prevent separation of the cusps and prevented from prolapsing (being driven into the right atrium) as ventricular pressure rises. Thus, regurgitation of blood (backward flow of blood) from the right ventricle back into the right atrium is blocked during ventricular systole by the valve cusp Papillary muscles insure Competence of the valve 15 The mitral valve guards the left atrioventricular orifice  It consists of two cusps. 16 The anterior cusp of the mitral valve THE SUBAORTIC CURTAIN Subjected to blood flow from two sides ??? 17  The left atrioventricular orifice admits atrial blood during diastole, flow being towards the cardiac apex.  After closure of the mitral cusps, and throughout the ejection phase of systole, blood is expelled from the apex through the aortic orifice The bloodstream undergoes two right angle turns, which together result in a 180° change in direction. This reversal of flow takes place around the anterior cusp of the mitral valve 18 Semilunar valves No chordae or papillary muscles are associated with these valves The pulmonary valve guards the pulmonary orifice and The aortic valve guards the aortic orifice. Each consists of three pocketlike cusps of approximately equal size There is no distinct, circular ring of fibrous tissue at the base of the arteries from which these and the valve cusps arise The arterial wall expands into three dilated pouches, the sinuses of Valsalva The cusps of the arterial semilunar valve are largely smooth and thin. At the center of the free margin of each cusp is a small fibrous nodule called The nodulus Arantii On each side of the nodules of Arantius, along the entire free edge of the cusp, there is a thin, halfmoon–shaped area called the lunula that has fine striations parallel to the edge The aortic valve consists of three semilunar cusps Posterior (non-coronary) cusp Right Left Just superior to right and left cusps in the Sinus of Valsalva are the openings of the right and left coronary arteries, respectively Pulmonary valve At the apex of the infundibulum, the outflow tract of the right ventricle, the opening into the pulmonary trunk is closed by the pulmonary valve consists of three semilunar cusps with free edges projecting upward into the lumen of the pulmonary trunk 3 semilunar cusps Anterior Right Left Opening of the pulmonary valve During diastole, the pulmonary valve is closed and all three cusps of the valve are tightly apposed. The pulmonary valve opens passively during ventricular systole and then closes rapidly at the end of systole

Valves of the Heart

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