Polygons are 2-dimensional shapes. They are made of straight lines, and the shape is closed (all the lines connect up).
Rectopexy is a surgical procedure used to correct rectal prolapse, a condition characterized by a weakening of the muscles that hold the rectum in place. Though the exact cause of this problem is unknown, there are several conditions that may contribute to its development.
Single Photon Emission Computed Tomography (SPECT). A nuclear imaging technique involving the injection of a radioactive tracer substance into the blood stream and resulting in 3-D images of internal brain structure and functioning.