The term 'FURROWED, AS MUSCLES' can be solved by the 8-letter word 'STRIATED'. STRIATED muscles are a type of muscle tissue that is composed of long, thin fibers. These muscles are found in the body and are responsible for voluntary movement. They are also known as skeletal muscles because they are attached to the bones. STRIATED muscles are characterized by their alternating light and dark bands, which give them a striped appearance. This pattern of light and dark bands is known as striation.