WordNet (r) 3.0 (2006):

voluntary muscle
    n 1: striated muscle that can be controlled voluntarily

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "voluntary muscle":
   adductor, beef, beefiness, biceps, brawn, brawniness, buccinator,
   elasticity, gemellus, gluteus maximus, heftiness, huskiness,
   infraspinatus, intercostal, involuntary muscle, latissimus dorsi,
   levator, masseter, mentalis, muscle, muscularity, musculature,
   mylohyoid, nasalis, oblique, occipitalis, omohyoid, pectineus,
   pectoralis, peroneus, physique, sinew, sinewiness, sinews,
   sphincter, tensor, thew, thewiness, thews, tone, trapezius,
   triceps