Skeletal muscle without antagonist Is there any skeletal muscle that does not have an antagonist? Excluding circular muscles such as around eye and mouth. The reason why I am wondering is because in biology normally nothing is ever just like that, there is always an exception. This would be the first biological rule without exception that I came across. I am thinking of humans only for a start but feel free to include any other animal if any have skeletal muscles without antagonists :)

I would argue that the orbiculares do have antagonists. To some extent, levator palpebrae superiorus antagonizes orbicularis oculi, and zygomaticus major/minor as well as risorius antagonize orbicularis oris.

I can think of three muscle that don't have obvious antagonists:

1. Stapedius
2. Tensor tympani
3. Articularis genu



1 and 2 essentially perform the same action, to dampen sounds reaching the cochlea. 3 elevates the suprapatellar bursa.