The muscle of thorax refers to the group of important muscles present in the upper chest region which are responsible for facilitating breathing, chest expansion and supporting the ribcage. Some common synonyms for this term include thoracic muscle, pectoral muscle, intercostal muscle, respiratory muscle, and diaphragm muscle. The thoracic muscle includes a number of highly specialized muscles such as the external and internal intercostals, levatores costarum, serratus anterior and posterior, and the diaphragm. These muscles work together to facilitate breathing and help to maintain the structural integrity of the thoracic cage, making them essential for both respiratory and musculoskeletal health.