Final answer:
The term for prolonged, fixed, rigid lack of movement could refer to a synarthrosis joint, which is immobile, aiding in protection of internal organs. It could also describe muscle conditions like hypotonia, characterized by low muscle tone and flaccid appearance, or hypertonia, which results in excessive muscle tone and rigidity.
Step-by-step explanation:
The prolonged fixed rigid lack of movement is usually associated with medical conditions affecting muscle tone or joints. In the context of joints, an immobile or nearly immobile joint is called a synarthrosis. This type of joint provides a strong union between bones and is crucial for the protection of internal organs, such as sutures found between skull bones and the manubriosternal joint that secures the sternum for cardiac protection.
In terms of muscle conditions, two conditions can be relevant: hypotonia, which is characterized by low muscle tone and flaccid appearance, and hypertonia, characterized by excessive muscle tone leading to muscle rigidity and often result from damage to upper motor neurons. Hypertonia can manifest through conditions such as Parkinson's disease and some strokes, where a limb will 'snap' back from passive stretching.
Learn more about Muscle Rigidity