CEA test: Carcinoembryonic antigen test is to detect response to therapy in cancer patients, especially colon cancer, with normal range of less than 2.5 (less than 5 in heavy smokers). Note that a positive test may not always be indicative of cancer.
Os Trigonum Syndrome. An Os Trigonum is a small, extra bone found at the back of the ankle in approximately 5-10% of people. Often it goes completely unnoticed, not causing any problems.
The corpus callosum is a large bundle of axons that connects the right and left cerebral hemispheres. The axons are processes of pyramidal cells in the cerebral cortex, and they carry information, in the form of patterns of nerve impulses, from cells of one hemisphere to cells in the contralateral hemisphere.