Question

multiple choice question
the sternocleidomastoid muscle is a muscle of forced

o inspiration
o expiration

Explanation:

The sternocleidomastoid muscle helps in elevating the sternum. When the sternum is elevated, the volume of the thoracic cavity increases, which is a part of the process of inspiration (breathing in). Forced inspiration involves the use of accessory muscles like the sternocleidomastoid. Expiration (breathing out) mainly involves muscles that decrease the thoracic cavity volume (like internal intercostals in forced expiration).

Answer:

inspiration