vestigial muscle

ves·tig·i·al mus·cle

an imperfect structure in humans corresponding to a functioning muscle in the lower animals.
References in periodicals archive ?
About 85% of people have what is called a palmaris longus, a vestigial muscle running from the elbow to the heel of the hand.
This muscle is not found in the domestic ruminants, only in domestic carnivores, and in the llama it has the appearance of a vestigial muscle.
Often dismissed as a small, vestigial muscle, injury of the plantaris muscle should actually be included in differential considerations of the painful calf.
Therefore, these results suggest that the activity of the MocuMA 1 promoter is somewhat "leaky" in some cell types, as is the transcription of Ache genes in vestigial muscle cells of several anural ascidian species (Whittaker, 1979; Jeffery and Swalla, 1990b; and Bates and Mallett, 1991).