Final answer:
Derangement or disc displacement refers to the movement of intervertebral discs out of their normal position, which can cause nerve compression and result in pain, especially when lifting heavy objects improperly. Displacement is also a concept in physics, describing the change in an object's position.
Step-by-step explanation:
A derangement, also known as disc displacement, refers to a condition where the intervertebral discs, which act as cushions between the vertebrae, move out of their normal position. This can sometimes lead to a herniated disc, where the disc material pushes out, often impinging on surrounding nerves. When heavy objects are lifted improperly, the spine can be subjected to excessive stress. This stress can lead to disc displacement or exacerbation of a pre-existing disc derangement, producing pain often felt in a lower limb due to nerve compression.
Displacement is also a term used in physics. It represents the change in an object's position, depicted as a vector from the initial to the final position. Displacement in kinematics can be studied to understand motion without the influence of forces, as seen in the equilibrium position, which is where an object would naturally rest in the absence of force.