Which of the following refers to the membrane surrounding joints?

The correct answer, Synovi/o, refers specifically to the synovial membrane, which is the connective tissue lining the joints. This membrane plays a crucial role in joint health by producing synovial fluid, which lubricates the joints and reduces friction between the cartilages of the joints during movement. Understanding this term is important in a medical context, as conditions affecting the synovial membrane, such as synovitis, can lead to joint pain and inflammation.

The other options pertain to different anatomical terms: Steth/o relates to the chest and is often associated with stethoscopes, which are used to listen to heart and lung sounds. Spir/o is associated with breathing or respiration. Spondyl/o refers to the vertebrae or spine. While each term has its own context and importance in medical terminology, only Synovi/o directly addresses the membrane surrounding joints, making it the correct choice.