In rigor mortis, the muscles contract hours after death due to a breakdown of the sarcoplasmic reticulum. this is because the sarcoplasmic reticulum stores acetylcholine, which triggers muscle contraction calcium, which triggers muscle contractions atp, which prevents myosin from detaching from actin tropomyosin, which prevents myosin from detaching from actin

The muscles of a dead person typically contract hours after death due to a breakdown of the sarcoplasmic reticulum, and fails to relax; this is known as rigor mortis. The contraction happens because the sarcoplasmic reticulum stores calcium, which triggers muscle contractions. Relaxation fails to occur because cross-bridges form, but can't release due to lack of ATP formation.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave