Truncus arteriosus (embryology)

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Truncus arteriosus
Heart of human embryo of about fourteen days. (Truncus arteriosis visible at top.)
Diagrams to illustrate the transformation of the bulbus cordis. Ao. Truncus arteriosus. Au. Atrium. B. Bulbus cordis. RV. Right ventricle. LV. Left ventricle. P. Pulmonary artery.
Gray's	subject #135 514
Gives rise to	aorta, pulmonary artery
MeSH	Truncus+Arteriosus

The truncus arteriosus and bulbus cordis are divided by the aorticopulmonary septum.

This makes its appearance in three portions.

(1) Two distal ridge-like thickenings project into the lumen of the tube; these increase in size, and ultimately meet and fuse to form a septum (aorticopulmonary septum), which takes a spiral course toward the proximal end of the truncus arteriosus. It divides the distal part of the truncus into two vessels, the aorta and pulmonary artery, which lie side by side above, but near the heart the pulmonary artery is in front of the aorta.

(2) Four endocardial cushions appear in the proximal part of the truncus arteriosus in the region of the future semilunar valves; the manner in which these are related to the aortic septum is described below.

(3) Two endocardial thickenings—anterior and posterior—develop in the bulbus cordis and unite to form a short septum; this joins above with the aortic septum and below with the ventricular septum. The septum grows down into the ventricle as an oblique partition, which ultimately blends with the ventricular septum in such a way as to bring the bulbus cordis into communication with the pulmonary artery, and through the latter with the sixth pair of aortic arches; while the left ventricle is brought into continuity with the aorta, which communicates with the remaining aortic arches.

Developmental anomalies

Failure of the truncus arteriosus to close results in the condition known a Persistent Truncus Arteriosus. One of cyanotic heart defects or congenital heart defects.

Additional images

Liver with the septum transversum. Human embryo 3 mm. long.

External links

• Embryology at UNSW Notes/heart3b
• Overview at mcgill.ca
• Description and diagram at umich.edu

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

v • d • e Prenatal development/Mammalian development of circulatory system
Vascular	Blood island arteries: Dorsal aorta - Aortic arches - Vitelline arteries - Ductus arteriosus - Umbilical artery veins: Cardinal veins - Ducts of Cuvier - Vitelline veins - Ductus venosus - Umbilical vein
Heart development	Primitive heart tube: Truncus arteriosus - Bulbus cordis - Primitive ventricle - Primitive atrium - Sinus venosus Septum primum (Ostium primum, Ostium secundum) - Septum secundum (Foramen ovale) - other septa (Endocardial cushions/Septum intermedium, Aorticopulmonary septum) - Atrial canal