Evolutionary study of the extrinsic thoracic limb muscles of the domestic cat (Felis catus, Feliformia, Carnivora) based on their topology and innervation

Extrinsic thoracic limb muscles are a muscular group that supports the thoracic limb in mammals without the clavicle and serve to move the scapula and shoulder joint. However, there are few evolutionary studies of these muscles in Felis catus, which should take into account the topology and innervation of the muscles to hypothesize the muscle derivation from a common ancestor. The main objective of this study was to check the extrinsic thoracic limb muscles in ten cadavers. Intra- and interspecific anatomical variants were found with that formerly described and other felids. Based on the topology and innervation found in this study, the evolutionary derivation was hypothesized. Therefore, the omotransversarius and rhomboideus muscles are derived from the serratus ventralis cervicis muscle. The cleidobrachialis muscle is derived mainly from the m. deltoideus and accessorily from the supracoracoid muscular group. The pectoantebrachialis and pectoralis abdominalis muscles are derived from the pectoralis descendens and cutaneus trunci muscles, respectively. In conclusion, most extrinsic thoracic limb muscles of F. catus may have evolutionary derivations from the last common ancestor of mammals, while some of them are from the last common ancestor of carnivorans or within the family Felidae.