What is the meaning of intra- in anatomy?

• A. Between two
• B. Too much/too little
• C. Against
• D. Within

Answer: (D)

In anatomy, the prefix intra- means inside or within a structure. It is used to describe something that occurs inside the boundaries of a particular organ or space, rather than outside or between things. For example, intracellular means inside a cell, intracranial means inside the skull, intraocular means inside the eye, and intravenous refers to something administered into a vein. This makes the meaning of intra- specifically “within.”

The other options point to different relationships: something between two things would be inter-; too much or too little would be hyper- or hypo-; and against would be anti-. These prefixes describe different spatial or functional relationships, not inside.