The Probert Encyclopaedia of Medicine

SEPTUM

The septum is a thick muscular wall that divides the heart lengthwise into the left and right sides. Before birth, an opening known as the foramen ovale in the septum allows oxygen from the mother to flow directly from the right to the left atrium, by-passing the lungs which do not function until the moment of birth. The foramen ovale normally closes at birth, but occasionally it remains open, resulting in poor circulation through the lungs where it fails to take up enough oxygen, causing the skin of the new-born child to turn blue. This condition is known as a hole in the heart and can often be repaired by surgery.
Research Septum