Truncus arteriosus (embryology)
Encyclopedia
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 caudal end of the bulbus cordis gives rise to the smooth parts (outflow tract) of the left and right ventricles (aortic vestibule & conus arteriosus respectively). The cranial end of the bulbus cordis (also known as the conus cordis) gives rise to the aorta and pulmonary trunk with the truncus arteriosus.
This makes its appearance in three portions.
(1) Two distal ridge-like thickenings project into the lumen of the tube: the truncal and bulbar ridges. 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.
, or simply "Truncus arteriosus," one of many cyanotic heart defect
s or congenital heart defects.
Other pathologies of the truncus arteriosus include transposition of the great vessels
(arteries in this case), and tetralogy of Fallot
.
Bulbus cordis
The bulbus cordis lies ventral to the primitive ventricle after the developing heart assumes its S-shaped form...
are divided by the aorticopulmonary septum
Aorticopulmonary septum
The aorticopulmonary septum is developmentally formed from neural crest, specifically the cardiac...
. The truncus arteriosus gives rise to the ascending aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
and the pulmonary trunk. The caudal end of the bulbus cordis gives rise to the smooth parts (outflow tract) of the left and right ventricles (aortic vestibule & conus arteriosus respectively). The cranial end of the bulbus cordis (also known as the conus cordis) gives rise to the aorta and pulmonary trunk with the truncus arteriosus.
This makes its appearance in three portions.
(1) Two distal ridge-like thickenings project into the lumen of the tube: the truncal and bulbar ridges. These increase in size, and ultimately meet and fuse to form a septum (aorticopulmonary septum
Aorticopulmonary septum
The aorticopulmonary septum is developmentally formed from neural crest, specifically the cardiac...
), 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
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
and pulmonary artery
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
, which lie side by side above, but near the heart the pulmonary artery is in front of the aorta.
(2) Four endocardial cushions
Endocardial cushions
Atrioventricular cushions or endocardial cushions refers to a subset of cells in the primordial heart that play a vital role in proper heart septation.They develop on the atrioventricular canal.During development the heart starts out as a tube...
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
Aortic arches
The aortic arches or pharyngeal arch arteries are a series of six paired embryological vascular structures which give rise to several major arteries...
; 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 as Persistent Truncus ArteriosusPersistent truncus arteriosus
Persistent truncus arteriosus , also known as Common arterial trunk, is a rare form of congenital heart disease that presents at birth...
, or simply "Truncus arteriosus," one of many cyanotic heart defect
Cyanotic heart defect
A cyanotic heart defect is a group-type of congenital heart defects . The patient appears blue , due to deoxygenated blood bypassing the lungs and entering the systemic circulation...
s or congenital heart defects.
Other pathologies of the truncus arteriosus include transposition of the great vessels
Transposition of the great vessels
Transposition of the great vessels is a group of congenital heart defects involving an abnormal spatial arrangement of any of the primary blood vessels: superior and/or inferior vena cavae , pulmonary artery, pulmonary veins, and aorta...
(arteries in this case), and tetralogy of Fallot
Tetralogy of Fallot
Tetralogy of Fallot is a congenital heart defect which is classically understood to involve four anatomical abnormalities...
.