| defensive circle | An obsolete term for the addition of a secondary affection that limits or arrests the progress of the primary affection, as thought to occur when pneumothorax supervenes on pulmonary tuberculosis, the former having a therapeutic effect on the latter. (05 Mar 2000) |
|---|---|
| objective circle | <microscopy> When the focused objective is examined by with- drawing the ocular and viewing its back focal plane through the microscope bodytube, the limiting boundary of the objective, the circumference of the white spot of light, is the objective circle. (05 Aug 1998) |
| Zinn's vascular circle | <anatomy, nerve> A network of branches of the short ciliary arteries on the sclera around the point of entrance of the optic nerve. Synonym: circulus vasculosus nervi optici, circulus arteriosus halleri, circulus zinnii, Haller's circle, Zinn's corona, Zinn's vascular circle. (05 Mar 2000) |
| least diffusion circle | In the configuration of rays emerging from a spherocylindrical lens system, the place where diverging rays of the lens first forming a line image are balanced by converging rays of the second lens. (05 Mar 2000) |
| lesser arterial circle of iris | An arterial circle near the pupillary margin of the iris. Synonym: circulus arteriosus iridis minor. (05 Mar 2000) |