The septum secundum is a
muscular flap that is important in
heart development
Heart development, also known as cardiogenesis, refers to the prenatal development of the heart. This begins with the formation of two endocardial tubes which merge to form the tubular heart, also called the primitive heart tube. The heart is ...
. It is semilunar in shape, and grows downward from the upper wall of the
atrium immediately to the right of the
septum primum and
ostium secundum. It is important in the closure of the
foramen ovale after
birth
Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
.
Structure
Development
At the end of the fifth week of development, the septum secundum grows from the upper wall of the
primitive atrium.
It grows to the right of the
septum primum, which has already started growing.
It grows down towards the
septum intermedium formed from the
endocardial cushions.
Before
birth
Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
, it does not fuse with the septum intermedium, leaving a gap to form the
foramen ovale.
Shortly after birth, it fuses with the
septum primum to form the
interatrial septum, and the foramen ovale is closed.
The
fossa ovalis denotes the free margin of the septum secundum after birth.
Clinical significance
Sometimes, the fusion of the septum secundum to the
septum intermedium is incomplete, and the upper part of the foramen remains patent.
This creates an
atrial septal defect (ASD).
References
External links
*
*
Overview at edu.mt*
Embryology of cardiovascular system
{{Portal bar, Anatomy