The muscles that are studied include those related to respiration. A number of other muscles are anatomically related to the thorax, but they are not functionally associated with this region. Examples include: Back muscles Muscles of the upper extremity such as the latissimus dorsi, pectoralis major and minor, and rhomboideus muscles.

The principal muscles of the thorax are:
External intercostal (anterior intercostal membrane)
Ixternal intercostal (posterior intercostal membrane)
Innermost intercostal (intercostalis intimus)
Transversus thoracis
Diaphragm