Which combining form pertains to the arachnoid?

• A. Menin/i
• B. Mening/o
• C. Mening/i
• D. Iatr/o

Answer: (A)

The arachnoid is a membrane layer that belongs to the meninges, the protective coverings of the brain and spinal cord. Medical terms use specific combining forms to name or describe these membranes, all tracing back to the root for meninges (the membranes). The form that directly denotes meninges in this group is the one built from the root meninx, giving the combining form menin-i (menin-). Because arachnoid is one of the meninges, this combining form specifically signals that membrane family, making it the best match for something pertaining to the arachnoid.

The other forms here point to related ideas but are not as direct for indicating the meninges in this context. For example, the form mening/o is also used to build terms about the meninges, but the question targets the exact combining form derived from the meninges’ root as shown, and iatr/o relates to treatment, not membranes.