Which combining form means back of the head or skull?

• A. poster/o
• B. cry/o
• C. cerebr/o
• D. dors/o

Answer: (D)

Understanding direction in medical terms relies on combining forms that describe where a structure is on the body. dors/o means the back or toward the back (the dorsal surface). Since the back of the head or skull is the dorsal aspect, dors/o is the appropriate combining form to convey that location.

The other forms point to unrelated ideas: cry/o means cold, cerebr/o refers to the brain (cerebrum), and poster/o denotes the back or behind in a more general sense, not specifically the dorsal surface of the head.