QS Study

Muscles of Respiration

The muscles of respiration are also called the ‘breathing pump muscles’; they form a complex arrangement in the form of semi-rigid bellows around the lungs. They are those muscles that contribute to breathing and exhalation, by aiding in the expansion and contraction of the thoracic cavity.

(A) Muscles of inspiration:

In quite an inspiration:

  • Diaphragm (chief muscles.75%) – The diaphragm is the major muscle responsible for breathing.
  • External intercostal muscle – They are three types: External intercostal muscles, internal intercostal muscles, and innermost intercostal muscles.

In forceful inspiration:-

  • Sternocleidomastoid muscles – The primary actions of the muscle are a rotation of the head to the opposite side and flexion of the neck.
  • Scalene muscle – The action of the posterior scalene is to elevate the second rib and tilt the neck to the same side.
  • Anterior serrati muscle – They might not be the most visible of muscles, but it’s quite important for our breathing and our movement.

Fig: Muscles of Respiration

(B) Muscles of expiration:

Quite an expiration: Does not involve any muscle.

In forceful expiration:

  • Abdominal recti,
  • Internal intercostals,
  • Serratus postrior inferior muscle.