Explanation

Sacral and coccygeal (caudal) vertebrae are fused vertebrae in human beings Sacral vertebrae First five sacral vertebrae gets fused to form sacrum. It is a strong and short supporting pelvic girdle as it (sacrum) articulates with the ilium of pelvic girdle Caudal or coccygeal vertebrae Mainly 3 to 4 caudal vertebrae gets fused to form a small triangular bone called coccyx. It is the vestigial tail in humans