🔙 The muscles of the back include those that move the vertebral column, help maintain posture, and are involved in movements of the pectoral girdle and arm. The muscles of the back can be categorised into two main groups: the extrinsic and the intrinsic muscles. The extrinsic muscles of the back are generally involved in movements of the pectoral girdle, arm and ribs. The most superficial of the extrinsic muscles are the trapezius and latissimus dorsi muscles. Deep to these muscles, in the inte