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Formation of the Cardiac Loop
The heart tube continues to elongate and bend on day 23. The cephalic portion-c of the tube bends ventrally, caudally, and to the right as shown in figure 1 (B-F). This portion is divided into the truncus arteriosus, conus cordis, bulbus cordis from the cephalic to the caudal direction respectively. The truncus arteriosus will form the aorta and the pulmonary artery, the conus cordis will form the outflow tract of both ventricles, and the bulbus cordis will form the trabeculated part of the right ventricle.
![Picture](/uploads/9/5/1/4/9514123/5229202.png?309)
Figure 1
The atrial-a (caudal) portion shifts dorsocranially and to the left as shown in figure 1 (E-F). This portion is initially a paired structure outside the pericardial cavity, but after the movement it forms a common atrium and is incorporated into the pericardial cavity.
The primitive ventricle-v is moving ventrally and to the right as shown in figure 1 (D-F)
The following video sums up the three movements. On the 28th day bending will be completed and the cardiac loop will be established.
The junction between the ventricle and the bulbus cordis is externally indicated as bulboventricular sulcus, and it is called the primary interventricular foramen.
The video below includes an animation which summarizes the process explained above.
Wait what could go wrong: Dextrocardia, in which the heart lies on the right side of the thorax instead of the left, and that's because the heart loops to the left in-stead of the right.
We recommend taking this quiz that will help you evaluate your knowledge after taking the tutorial.
Prepared by Joy Y. Balta