Deep groupSerratus posteriorinferiorSerratus posteriorsuperiorSuboccipitalLevator scapulaeSpleniusRhomboid minorSuperficial groupABIntermediate groupIntrinsic musclesTrue back muscles innervated by posterior rami of spinal nervesRhomboid majorSpinalisIliocostalisErector spinaeLongissimusLatissimusdorsiTrapeziusExtrinsic musclesInnervated by anterior rami of spinal nerves or cranial nerve XI (trapezius)