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. The truncus arteriosus gives rise to the ascending aorta and the pulmonary trunk. The bulbus cordis gives rise to the smooth parts (outflow tract) of the left and right ventricles.^[1]

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.

Contents 1 Developmental anomalies 2 Additional images 3 References 4 External links

[edit] 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.

[edit] Additional images

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

[edit] References

[edit] 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 within it may be outdated.

v • d • e Prenatal development/Mammalian development of circulatory system (GA 5) Vascular Blood island Development of arteries Dorsal aorta · Aortic arches Development of veins Cardinal veins · Ducts of Cuvier Fetal circulation umbilical cord: Umbilical vein → Ductus venosus → Inferior vena cava → Heart → Pulmonary artery → Ductus arteriosus → Umbilical artery yolk sac: Vitelline veins · Vitelline arteries Heart development Primitive heart tube Truncus arteriosus · Bulbus cordis · Primitive ventricle · Primitive atrium · Sinus venosus Septa/ostia Endocardial cushions/Septum intermedium · Ostium primum · Septum primum (Ostium secundum) · Septum secundum (Foramen ovale) · Aorticopulmonary septum Other Atrial canal heart navs: anat/physio/dev, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc

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