Septum secundum

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Septum secundum
Septum primum and Septum secundum - early 7th week.jpg
A labelled diagram of the developing heart, showing the relationship between the septum secundum (by the right atrium) and the septum primum (by the left atrium).
Gray468.png
Same heart as above, opened on right side. (Septum secundum visible in dark area at center top.)
Details
Carnegie stage 14
Days33
Gives rise to atrial septum
Identifiers
Latin septum secundum
Anatomical terminology

The septum secundum is a muscular flap that is important in heart development. 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.

Contents

Structure

Development

At the end of the fifth week of development, the septum secundum grows from the upper wall of the primitive atrium. [1] It grows to the right of the septum primum, which has already started growing. [1] It grows down towards the septum intermedium formed from the endocardial cushions. [1] Before birth, it does not fuse with the septum intermedium, leaving a gap to form the foramen ovale. [1] Shortly after birth, it fuses with the septum primum to form the interatrial septum, and the foramen ovale is closed. [1] 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. [2] This creates an atrial septal defect (ASD). [2]

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<span class="mw-page-title-main">Fossa ovalis (heart)</span> Feature of the right atrium in the human heart

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<span class="mw-page-title-main">Foramen ovale (heart)</span> Passageway between the atria of the human heart

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<span class="mw-page-title-main">Interatrial septum</span> Wall of tissue separating atria of human heart

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<span class="mw-page-title-main">Primitive ventricle</span>

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During heart development of a human embryo, the single primitive atrium becomes divided into right and left by a septum, the septum primum. The septum primum grows downward into the single atrium.

<span class="mw-page-title-main">Foramen secundum</span>

The foramen secundum, or ostium secundum is a foramen in the septum primum, a precursor to the interatrial septum of the human heart.

<span class="mw-page-title-main">Primary interatrial foramen</span>

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Lutembacher's syndrome is a very rare form of congenital heart disease that affects one of the chambers of the heart as well as a valve. It is commonly known as both congenital atrial septal defect (ASD) and acquired mitral stenosis (MS). Congenital atrial septal defect refers to a hole being in the septum or wall that separates the two atria; this condition is usually seen in fetuses and infants. Mitral stenosis refers to mitral valve leaflets sticking to each other making the opening for blood to pass from the atrium to the ventricles very small. With the valve being so small, blood has difficulty passing from the left atrium into the left ventricle. Septal defects that may occur with Lutembacher's syndrome include: Ostium primum atrial septal defect or ostium secundum which is more prevalent.

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<span class="mw-page-title-main">Heart development</span> Prenatal development of the heart

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References

PD-icon.svgThis article incorporates text in the public domain from page 512 of the 20th edition of Gray's Anatomy (1918)

  1. 1 2 3 4 5 Belmont, John W. (2015-01-01), Moody, Sally A. (ed.), "Chapter 33 - Genetic and Developmental Basis of Congenital Cardiovascular Malformations", Principles of Developmental Genetics (Second Edition), Oxford: Academic Press, pp. 607–633, ISBN   978-0-12-405945-0 , retrieved 2021-01-05
  2. 1 2 Carlson, Bruce M. (2014-01-01), "Development of the Heart", Reference Module in Biomedical Sciences, Elsevier, doi:10.1016/b978-0-12-801238-3.05460-x, ISBN   978-0-12-801238-3 , retrieved 2021-01-05