Which part of the body has no muscle?

The part of the body with no muscle is the hair. Hair itself is made up of keratin, a protein, and contains no muscle tissue.

Another example includes the nails, which are also composed of keratin and have no muscles.

Additionally, the cornea of the eye has no muscles; it is a transparent layer that covers the front of the eye and gets its shape and movement from surrounding muscles but contains no muscle tissue itself.