Heart - LO 6

6. Identify the unique structures of the left atrium.

The left atrium receives the pulmonary veins from the lungs. 

Auricle (appendage): muscular pouch that is located in the superior, left border (often overlapping the root of the pulmonary trunk)

• Internally, has pectinate muscles

  • Only area of the internal L. atrium with pectinate muscle (the rest is mostly smooth-walled)

L. atrioventricular (mitral) valve orifice

• The L. AV valve is located between the L. atrium and L. ventricle

Interatrial septum

• Wall between the R. and L. atrium

Semilunar depression: a small depression in the interatrial septum that represents the floor of the fossa ovalis