Morphology/Structure
The left ventricle is conical in shape. It’s the dominant chamber of the heart and has the thickest walls (up to 12 mm). A small portion of the left ventricle helps to form the anterior, sternocostal surface which includes the apex. However, the majority of the left ventricle forms the inferior, diaphragmatic surface of the heart.
The inlet of the left ventricle contains the left atrioventricular valve (or mitral valve), while its outlet contains the aortic valve. The majority of the internal surface contains deep muscular ridges, the trabeculae carneae (or fine apical trabeculations), which are highly varied in appearance but are most developed at the apex. These are not to be confused with the ridges of pectinate muscles found in the atria.
The outflow tract of the left ventricle is named the aortic vestibule and is smooth walled surrounding the aortic orifice. The interventricular septum separates the left and right ventricles and thins near the aortic opening, where it becomes the membranous septum.
Key Features/Anatomical Relations
Externally, the left ventricle is separated from the left atrium by the coronary (atrioventricular) sulcus. It’s separated from the right ventricle by the anterior and posterior interventricular sulci which mark the location of the interventricular septum.
Internally, the papillary muscles are muscular bundles that extend from the ventricular walls and end in the thin collagenous cord, the chordae tendineae, which insert into the leaflets of the left atrioventricular valve (or mitral valve).
Function
During left atrial contraction (atrial systole), the left ventricle is relaxed (ventricular diastole), allowing the oxygenated blood to enter the ventricle without resistance. As the left atrium relaxes and refills (atrial diastole), the left ventricle contracts (ventricular systole). This forces the oxygenated blood through the aortic valve and into the aorta for transport to the systemic tissues. The trabeculae carneae prevent suction of the blood, which would impair the pumping action and decrease the efficiency of the heart.
List of Clinical Correlates
- Ventricular septal defects
