This truncus consists of two parts: the first, the conus or pylangium (c.
In the rabbit both sinus and truncus are absent, or merged in the adjacent parts of the heart.
The truncus arteriosus may then be followed up as it branches.
Lepus, the truncus arteriosus and the sinus venosus, into the latter of which the venous blood runs before entering the right auricle, are to be noted.
The tadpole has, at first, a straight tubular heart, burrowed out in somatic mesoblast, and produced forward into a truncus arteriosus.
That division of the truncus which opens into the fifth pair of arches is the one which communicates with the right ventricle, while that which opens into the third and fourth pairs communicates with the left ventricle.
In the embryos of Vertebrata the arterial system consists of a forward continuation of the truncus arteriosus, on the ventral side of the throat (figs.
The external constriction actually dividing the truncus into two vessels does not begin to appear till the septum has extended some way back towards the heart.
The truncus arteriosus lies to the left, and is continued into the ventricle which lies ventrally and more to the right, and this again into the dorsally placed auricular section.
The most important feature in which the development of the Reptilian heart differs from that of Birds is the division of the truncus into three vessels, instead of two.
At the time when the septum is first formed, the opening of the truncus arteriosus into the ventricles is narrow or slit-like, apparently in order to prevent the flow of the blood back into the heart.
Its course downwards is not straight but spiral, and thus the two channels into which it divides the truncus arteriosus wind spirally the one round the other.
Of these the main parts of the first two, connecting the truncus arteriosus with the collecting trunk into which the arterial arches fall, always disappear, usually before the complete development of the arteries in the posterior arches.
The sinus venosus in Mammals becomes completely merged into the right auricle, and the systemic division of the truncusarteriosus is apparently not homologous with that in Birds.
A and B), but with the division of the truncus arteriosus into three vessels one of these, i.
This vein is originally formed of two vessels, which at first fall directly into the sinus venosus, uniting close to their opening into the sinus with a vein from the truncus arteriosus.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "truncus" in a variety of sentences. We hope that you will now be able to make sentences using this word.
