Heart - LO 5

5. Identify the unique structures of the right ventricle.

Right atrioventricular (tricuspid) valve

• Composed of 3 valve cusps which attach to the fibrous ring surrounding the right AV orifice

  • Cusps are drawn together before R. ventricular contraction, thus preventing the flow of blood from the R. atrium to the R. ventricle to direct the flow of blood through the pulmonary valve

  • Close during systole; open during diastole

• Chordae tendineae: thin cords that attach to neighboring valve cusps from an origin of the papillary muscles; prevent prolapse

• Papillary muscles: three extensions of myocardium, which attach to chordae tendineae for each cusp of the tricuspid valve

  • Anterior, posterior, and septal papillary muscles

  • Anterior papillary muscle is the largest

Septomarginal trabecula (moderator band): a specialized bundle of trabecular muscle that is located between the base of the anterior papillary muscle and the inferior portion of the interventricular septum

• A portion of the R. atrioventricular (AV) bundle is located within this muscle

Trabeculae carneae: muscle elevations (beams, ridges) located on ventricular walls

Interventricular (IV) septum: located between the R. and L. ventricles

• Composed of muscular (predominantly) and membranous parts

Conus arteriosus: a relatively smooth (and cone-shaped) portion of the wall leading into the pulmonary trunk

Pulmonary valve

• This valve is located between the R. ventricle and the pulmonary trunk

• Has three, semilunar cusps (anterior, right, and left)

• When blood is pumped through the R. ventricle into the pulmonary trunk, the cusps project into the trunk

  • When relaxation of the ventricle occurs, the cusps meet (‘snap close’) to prevent blood from returning to the ventricle

• Close during diastole; open during systole