Which condition is characterized by excessive muscle tone that affects joint movement?

The condition characterized by excessive muscle tone affecting joint movement is hypertonicity. Hypertonicity refers to a state of increased muscle tension and is often associated with conditions that affect the central nervous system. This heightened tone can lead to stiffness in the muscles, making it difficult for an individual to move their joints freely, which can impact range of motion and functional mobility.

In contrast, hypotonicity describes decreased muscle tone, making muscles feel floppy and weak instead. Myasthenia gravis is an autoimmune neuromuscular disorder that leads to varying degrees of skeletal muscle weakness, not increased tone. Agnosia is a condition involving the inability to recognize objects, people, or sounds, which does not relate to muscle tone or joint movement. Understanding hypertonicity is essential for Occupational Therapy Assistants as it affects treatment planning and interventions aimed at improving client mobility and overall function.