Which combining form is used to indicate the skull?

• A. Cycl/o
• B. Conjuctiv/o
• C. Crani/o
• D. Cost/o

Answer: (C)

Crani/o is the combining form for the skull. It comes from cranium, the medical term for the skull, and it’s used to build words like cranial (relating to the skull), craniotomy (surgical opening of the skull), and cranioplasty (skull reconstruction). The other roots refer to different structures: cycl/o relates to the circle or to parts of the eye like the ciliary body, conjunctiv/o refers to the conjunctiva of the eye, and cost/o means rib. So crani/o is the correct form for indicating the skull.