muscle:musculus biceps brachii two-headed muscle on the ventral side of upper arm, biceps muscle; m. deltoideus shoulder muscle, deltoid muscle; m. gastrocnemius calf muscle; m. glutaeus buttock muscle, gluteal muscles; m. masseter, masticating or chewing muscle. m. pectoralis chest muscle, pectoral muscle; m. psoas lumbar muscle; m. rectus abdominis straight abdominal muscle.