How long is the spinal cord typically?

The spinal cord typically measures about 18 to 20 inches in length in adults, making 18 inches a reasonable approximation for its average size. It extends from the base of the skull, specifically from the medulla oblongata, down through the vertebral column, terminating around the area of the first or second lumbar vertebrae. This length allows for the spinal cord to remain protected within the vertebrae while providing a pathway for signals between the brain and the body.

Variations exist among individuals due to factors like genetic differences, and the spinal cord itself has a tapered end called the conus medullaris which contributes to the overall length. The other options do not accurately reflect the typical length of the spinal cord; 12 inches is too short and would not account for its full extent, while 24 inches and 30 inches exceed the usual measurements found in anatomical studies.