What anatomical term refers to structures that are fused together at the end of the spinal column?

The term that refers to structures fused together at the end of the spinal column is "coccyx." The coccyx, commonly known as the tailbone, consists of a small, triangular bony structure made up of three to five fused vertebrae. This fusion occurs during development and serves as an attachment point for various muscles, ligaments, and tendons in the pelvic region.

In contrast, the other terms do not relate to the spinal column. "Canthus" refers to the corner of the eye where the upper and lower eyelids meet. "Cochlea" is a spiral-shaped organ in the inner ear involved in hearing. "Cornea" is the transparent front layer of the eye that helps focus light. Each of these terms relates to different anatomical structures and functions, further confirming why "coccyx" is the correct choice in this context.