Which term refers to the three small vertebrae at the bottom of the spine?

The term that refers to the three small vertebrae at the bottom of the spine is the coccyx. The coccyx, commonly known as the tailbone, is made up of three to five fused vertebrae that form the terminal end of the vertebral column. This structure is significant as it serves as an attachment site for various muscles, tendons, and ligaments, contributing to pelvic stability and support.

Other terms mentioned in the options relate to different parts of the spine or skeletal structure. The sacrum consists of five fused vertebrae located just above the coccyx, forming the posterior part of the pelvis. The pelvis itself is a large bony structure that supports the spine and houses and protects several organs. The lumbar region refers to the five vertebrae in the lower back, which are larger and play a crucial role in weight-bearing and movement flexibility. Understanding these distinctions helps clarify the specific anatomical role and positioning of the coccyx within the broader framework of the human skeletal system.