A nurse is working with a group of clients on stretching. Which of the following statements about muscles is correct?

This question requires an understanding of the physiological properties of skeletal muscle tissue, specifically elasticity and extensibility. Knowledge of muscular mechanics is necessary to distinguish between the ability to stretch and the ability to return to a resting state after movement. Choice A rationale . Contractility refers specifically to the ability of muscle cells to shorten forcefully to generate tension and movement. It is not the property responsible for returning to the original shape, which is a characteristic defined as elasticity in physiology. Choice B rationale . Extensibility allows muscles to stretch beyond resting length without damage, while elasticity enables them to recoil to their original size. These combined properties are essential for joint range of motion and maintaining the structural integrity of the musculoskeletal system. Choice C rationale . Spasticity is a pathological condition involving increased muscle tone and involuntary contractions, usually due to central nervous system damage. It is not a normal physiological mechanism that facilitates the standard coordinated process of muscle flexion and relaxation. Choice D rationale . Muscles do not remain in a fixed position; they are the primary active contractile units that pull on tendons to move bones. Ligaments provide joint stability by connecting bone to bone and have much less elasticity than muscle fibers.