Facet joint – A connection point between vertebrae. These joints keep the spine aligned as it moves.
Fatigue – A general worn-down feeling of having no energy. Fatigue can be caused by excessive physical, mental or emotional exertion, by lack of sleep or by inflammation or disease.
Femoral head – The round bony protrusion at the end of the thigh bone that fits into the acetabulum (socket) of the pelvis to form the hip joint.
Femur – The bone in the upper leg, or thigh. The top end of the femur meets with the pelvis to form the hip joint.
Fibromyalgia – A syndrome characterized by widespread muscle pain, the presence of tender points (or points on the body that feel painful on pressure) and often debilitating fatigue.
Fusion – A surgical procedure in which bones that form a joint are held in place with metal screws or plates, allowing them to fuse into a single, immovable unit. Also called arthrodesis.