The two primary muscles used for breathing are the diaphragm and the:

The muscles of respiration are muscles that contribute to exhalation and inhalation by causing the contraction and expansion of the thoracic cavity. However, diaphragm is the main muscle of breathing while intercostal muscles is one of the most important muscles for respiration. Intercostal muscles function by manipulating the width of the rib cage and they are attached between the ribs.

bradykinin is a physiologically and pharmacologically active peptide of the kinin group of proteins, consisting of nine amino acids.