Question

Which muscles assist in inhalation when running up the stairs? A) sternocleidomastoid, pectoralis major, scalenes B) sternocleidomastoid, pectoralis minor, scalenes C) rectus abdominis, pectoralis major, scalenes D) rectus abdominis, pectoralis major, internal intercostals E) sternocleidomastoid, pectoralis major, internal intercostals

Answer 1

Answer:

Sternocleidomastoid, pectoralis minor, scalenes

Explanation:

During normal inhalation, contraction of the diaphragm and the contraction of external intercostals expands the chest cavity. The increased volume of the thoracic cavity results in reduced alveolar pressure than the atmospheric pressure to facilitate the flow of air into the lungs in response to the pressure gradient.

During deep inhalation as it occurs when running up the stairs, the accessory muscles of inhalation also participate to increase the volume of the chest cavity. The contraction of scalene and sternocleidomastoid muscles increase the volume of the chest cavity further to create a greater drop in alveolar pressure.

During forceful inhalation, the sternocleidomastoid muscles serve to elevate the sternum, the scalene muscles serve to elevate the first two ribs while the pectoralis minor elevate the third through fifth ribs.

Answer 2

Answer:

The correct answer will be option-B

Explanation:

The muscles used in the breathing process involves the thoracic muscles like external intercostal muscles, internal intercostal muscles, muscles attached to thoracic muscles like pectoralis major and minor and the accessory muscles like sternocleidomastoid muscle and scalene muscles.

The muscles involved in the inhalation process during running up the stairs are scalenes which help elevate the upper first and second ribs, the sternocleidomastoid muscle which helps to raise the sternum and the pectoralis minor.

Thus, Option-B is the correct answer.