Accessory muscles of respiration

The accessory muscles of respiration consist of the scalene muscles, which elevate the sternocleidomastoid muscle; the wing of the nose, which cause nasal flaring; and the small muscles in the neck and head.

Accessory muscles do not contract during normal breathing, however, they do contract vigorously during exercise or when airway obstruction is significant, and they actively pull up on the rib cage. During normal breathing, they only anchor the sternum and upper ribs.