Concept: This question tests your knowledge of the anatomical structures that anchor and terminate the spinal cord within the vertebral column.

Why (C) is correct: The spinal cord tapers into a cone-shaped structure called the conus medullaris. From the apex of the conus medullaris, a thin, fibrous strand of pia mater, called the filum terminale, extends downwards. This filum terminale anchors the spinal cord to the posterior surface of the coccyx, preventing it from moving upwards during body movements.

Why other options are wrong:

• (A) cauda equina: This refers to the bundle of spinal nerves (lumbar and sacral) that extend inferiorly from the conus medullaris, resembling a horse's tail. It does not anchor the spinal cord.
• (B) conus medullaris: This is the tapered, cone-shaped end of the spinal cord itself, not the anchoring structure.
• (D) corpus callosum: This is a large, thick nerve tract that connects the two cerebral hemispheres in the brain; it has no role in anchoring the spinal cord.

Common Mistake: Students often confuse the conus medullaris (the end of the spinal cord) with the filum terminale (the anchoring filament) or the cauda equina (the nerve roots).

NEET Tip / Mnemonic: Remember that the filum terminale is the "filament" that "terminates" the spinal cord's movement by anchoring it.

Correct Answer: (C)