Page 154 - Clinical Pearls in Cardiology

142 Clinical Pearls in Cardiology

• Pulmonary vein—smooth portion of left atrium
• Sinus venosus—smooth portion of right atrium.
5. What do you know about the development of
interventricular septum?
The interventricular septum has a large muscular
part and a small membranous part. The muscular
part of the interventricular septum grows as a ridge
of tissue from the caudal heart wall towards the fused
endocardial cushions. The interventricular foramen is
the opening remaining between the muscular part of
the interventricular septum and the fused endocardial
cushions (Fig. 1). This foramen, in turn is closed by
the membranous part of the interventricular septum,
which is formed by the fusion of tissue from three
sources: (1) The conal ridges; (2) An outgrowth of the
inferior endocardial cushion (i.e. the right tubercle);
(3) Connective tissue from the muscular interventricular
septum.

Fig. 1: Development of the interventricular septum