Appendicular Muscles Insert on girdles, limbs or fins Extrinsic muscles originate from blastemas within body wall and insert on girdle or proximal limb element Intrinsic muscles originate from blastemas within developing limb

Fish - paired fins operate as unjointed appendages. Dorsal and ventral extrinsics form levators and depressors. Tetrapods - complex appendicular muscles to accomplish movement at joints. Opposing (antagonistic) groups. Both extrinsic and intrinsic

Extrinsics of Pectoral Girdle and Forelimb Dorsal group: latissimus dorsi, levator scapulae ventralis, levator scapulae dorsalis, rhomboideus and trapezius (acromiotrapezius, cleidotrapezius, acromiotrapezius). Note: the trapezius originates from neural crest and is a muscle of the pharyngeal arch, innervated by cranial nerve.

Ventral group: (pectoral muscles) pectoralis major and minor. In birds, the supracoracoideus which becomes the supracoracoid in mammals (intrinsic).

Intrinsics of Pectoral Girdle and Forelimb Dorsal group: deltoideus, teres major and minor, subscapularis, long head of triceps, supinators and extensors of manus. Ventral group: supraspinatus, infraspinatus, coracobrachialis, biceps brachii, brachialis, anconeus, epitrochleoanconeus, pronators and flexors of manus.

Muscles of Pectoral Girdle and Hind Limbs Primarily intrinsic, however urodeles, reptiles and birds have a caudofemoralis which is extrinsic. In tetrapods below mammals, these muscles are named for attachments.

Rotators and abductors: iliacus and psoas major (rotate); gluteus, pyriformis and gemelli (abduct and rotate) Extensors and adductors: quadratus femoris complex (rectus femoris, vastus lateralis, vastus medialis and vastus intermedius), semimembranosus, adductor femoris, adductor longus, pectineus, sartorius and gracillis Flexors: biceps femoris, semitendinosus and gastrocnemis Obturators flex, rotate and abduct

Innervation: spinal nerves originating in same segment that contributes to muscle bud