Septal Papillary Muscle of Right Ventricle
Muscularis papillaris septalis ventriculi dextri
Read moreMorphology/Structure
The septal papillary muscle is the smallest of the three papillary muscles found in the right ventricle. The other two papillary muscles are the anterior and inferior papillary muscles. Each papillary muscle is a conical muscular bundle that extends from the ventricular wall and to the chordae tendineae. The chordae tendineae in turn insert into the leaflets of the right atrioventricular valve. The chordae tendineae attach to the apical one third of the papillary muscles but occasionally attach to the base of the papillary muscles.
Key Features/Anatomical Relations
The septal papillary muscle is medially placed and originates along the septal wall and may be a posterior extension of the septomarginal trabecula. The septal papillary muscle is attached to the anterosuperior and septal leaflets inferior to the anteroseptal commissure.
Function
During atrial contraction, the papillary muscles are relaxed, and the valve is open, avoiding any resistance to the movement of blood from the atrium to the ventricle. The papillary muscles contract just before ventricular systole. During ventricular contraction the valve leaflets close. This is achieved by papillary muscle contraction, thus pulling on the chordae tendineae and valve leaflets. This tension prevents the leaflets swinging backwards into the atria. The tension in the papillary muscles remains until the next atrial contraction.
The pulmonary valve does not require papillary muscles, as their inherent semilunar shape lends them the stability required to prevent retrograde blood flow and the extension of the pulmonary valve leaflets into the pulmonary trunk.
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Right Ventricular Papillary Muscle
RV papillary muscle VAs display an LBBB pattern with a QS or rS pattern in lead V1 and a wider QRS complex and more prevalent notching than in RVOT VA.
