What is the correct order of appearance and passing of rigor mortis among the following structures: jaws, muscles of the eyes, chest, face and neck muscles, lower extremities, upper extremities?

What is the correct order of appearance and passing of rigor mortis among the following structures: jaws, muscles of the eyes, chest, face and neck muscles, lower extremities, upper extremities?

• A. 1,2,3,4,5,6
• B. 2,1,4,3,6,5
• C. 2,4,1,3,5,6
• D. 1,2,4,3,5,6

Answer: (B)

Rigor mortis starts when ATP is depleted in muscle cells and calcium cannot be pumped back, causing actin–myosin cross-bridges to form and remain; the order it appears depends on muscle size, usage in life, and blood supply. Small, highly active muscles fatigue and stiffen first, then the rest of the body follows in a head-to-toe pattern as energy stores are exhausted. So, the earliest rigors appear in the muscles around the eyes, then in the jaw, followed by the other facial and neck muscles. Next come the chest muscles in the trunk, and finally the limbs, with the upper extremities stiffening before the lower ones. This progression reflects how these muscles differ in mass and metabolic reserve, leading to a cranial-to-caudal spread of rigidity.

Rigor mortis starts when ATP is depleted in muscle cells and calcium cannot be pumped back, causing actin–myosin cross-bridges to form and remain; the order it appears depends on muscle size, usage in life, and blood supply. Small, highly active muscles fatigue and stiffen first, then the rest of the body follows in a head-to-toe pattern as energy stores are exhausted.

So, the earliest rigors appear in the muscles around the eyes, then in the jaw, followed by the other facial and neck muscles. Next come the chest muscles in the trunk, and finally the limbs, with the upper extremities stiffening before the lower ones. This progression reflects how these muscles differ in mass and metabolic reserve, leading to a cranial-to-caudal spread of rigidity.