| primum mobile | <astronomy> In the Ptolemaic system, the outermost of the revolving concentric spheres constituting the universe, the motion of which was supposed to carry with it all the inclosed spheres with their planets in a daily revolution from east to west. See Crystalline heavens, under Crystalline. "The motions of the greatest persons in a government ought to be, as the motions of the planets, under primum mobile." (Bacon) Origin: L, first cause of motion. Source: Websters Dictionary (01 Mar 1998) |
|---|
| septum primum | A crescentic septum in the embryonic heart that develops on the dorsocephalic wall of the originally single atrium and initiates its partitioning into right and left chambers; the tips of the septum grow toward and fuse with the atrioventricular canal cushions. (05 Mar 2000) |
|---|---|
| interatrial foramen primum | In the embryonic heart, the temporary opening between right and left atria situated between the lower margin of the septum primum and the atrioventricular canal cushions, in an adult heart, the abnormal persistence of the so-named communication which is normal in young embryos. Synonym: foramen subseptale, ostium primum, primary interatrial foramen. (05 Mar 2000) |
| ostium primum | In the embryonic heart, the temporary opening between right and left atria situated between the lower margin of the septum primum and the atrioventricular canal cushions, in an adult heart, the abnormal persistence of the so-named communication which is normal in young embryos. Synonym: foramen subseptale, ostium primum, primary interatrial foramen. (05 Mar 2000) |