Dictionary

Rx 1 On a prescription, abbreviation for recipe (Latin for “to take”). See also Appendix A, “Prescription Abbreviations.” 2 In a pharmacological catalog, an indicator that one will need a prescription to buy a listed item.

SA node Sinoatrial node.

Sabin vaccine See polio vaccine, oral.

sac, egg See ovary.

sac, pericardial See pericardium.

saccular Being like a small pouch. For example, the alveolar saccules are little air pouches within the lungs.

saccular aneurysm See aneurysm, saccular.

sacral Referring to the sacrum. For example, sacral agenesis is absence of all or part of the sacrum.

sacral agenesis Absence of all or part of the sacrum. See also caudal regression syndrome; sacrum.

sacral vertebrae The five vertebral bones situated between the lumbar vertebrae and the coccyx (tailbone). By adulthood, the sacral vertebrae are normally fused to form the sacrum. The sacral vertebrae are represented by the symbols S1 through S5. See also vertebra; vertebral column.

sacrum The large heavy bone at the base of the spine that is made up of the fused sacral vertebrae. In the vertebral column, the sacrum is situated between the lumbar vertebrae and the coccyx (tailbone). It is triangular in shape and forms the back wall of the pelvis. The female sacrum is wider and…

SAD Seasonal affective disorder.