Muscles of thoracic wall (Anterior view) (Latin)

The mm. externi of the thoracic wall include the m. subclavius, m. pectoralis major and m. pectoralis minor and m. serratus anterior. The short, triangular m. subclavius is located beneath the clavicula and mainly functions in anchoring and depressing the bone. The large m. pectoralis major arises from three heads (pars clavicularis, pars sternocostalis and pars abdominalis) which unite before inserting into the sulcus intertubercularis of the humerus. Deep to the m. pectoralis major, is the smaller m. pectoralis minor. The m. pectoralis major primarily flexes, adducts and internally rotates the arm at the articulatio glenohumeralis on contraction, while the m. pectoralis minor stabilizes and draws the scapula anteroinferiorly. Located along the anterolateral aspect of the thoracic wall is the large fan shaped m. serratus anterior. This muscle primarily functions to rotate and draw the scapula anterolaterally. All of the mm. externi of the thoracic wall participate in elevation of the costae during forced inspiration as a secondary function.The mm. interni evident from this anterior view include the mm. intercostales, mm. subcostales and m. transversus thoracis. Lying beneath the large mm. externi of the thoracic wall are the mm. Intercostales (mm. intercostales externi, mm. intercostales interni and mm. intercostales intimi). These muscles are located within the spatia intercostalia and function to elevate, stabilize or depress the skeleton thoracis and therefore facilitate breathing movements. The mm. subcostales are bands of muscle located on the facies interna of the costae inferiores, sharing a plane with the mm. intercostales interni. They support the spatia intercostalia and skeleton thoracis, and depress the costae during forced expiration. Also located along the internal aspect of the thoracic cage is the m. transversus thoracis. This is a weak muscle of the skeleton thoracis which assists in expiration.