We don't have synonyms for trapeziuses yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are trapezius and trapeziums.
(n) :
(anatomy) A large vertebrate skeletal muscle divided into an ascending, descending, and transverse portion, attaching the neck and central spine to the outer extremity of the scapula; it functions in scapular elevation, adduction, and depression.
(n) :
(anatomy) A large vertebrate skeletal muscle divided into an ascending, descending, and transverse portion, attaching the neck and central spine to the outer extremity of the scapula; it functions in scapular elevation, adduction, and depression.