Muscle contraction (spasm) is one of the body’s protective mechanisms when an area of the body is injured. For example when a spinal joint gets 'locked the surrounding musculature will tighten to help prevent any movement causing further damage.
Ligaments connect bones to other bones to form a joint; they are not elastic like muscles. Ligaments are designed to limit the mobility of joints or prevent some movements altogether. Commonly injured/strained ligaments are those of the knee (anterior/posterior cruciate and medial/lateral collateral ligaments) ankle, and neck (whiplash).
Nerve pain is characterized by pain that is burning, shooting (often to distant areas), or stabbing. It also has an "electric" quality about it. "Tingling or numbness" (paresthesia) and increased sensitivity with normal touch are also commonly seen. Ongoing pain is often continually present regardless of what the patient does or does not do. In some cases, pain comes in sudden attacks without any apparent trigger.
It is common for a nerve to become irritated when the surrounding tissues have become inflamed. Some places in the spine, arms and legs are particularly vulnerable to this type of injury as the nerve has less space in which to move and slide as it passes between structures.