Coccygeal Vertebrae (Tailbone): Anatomy, Function, and Injury

The coccyx is a triangular bone formed by 3–5 fused rudimentary vertebrae (Co1–Co4/5) at the caudal end of the vertebral column.

Anatomy

• Articulates superiorly with sacrum (sacrococcygeal joint – fibrocartilaginous).
• Anterior: attachment for levator ani, coccygeus (pelvic floor).
• Posterior: gluteus maximus, sacrococcygeal ligaments.
• Vestigial remnant of ancestral tail; no locomotor function in humans.

Functions

• Weight-bearing in sitting (with ischial tuberosities).
• Anchor for pelvic floor muscles (support viscera, continence).
• Attachment for anococcygeal raphe, sacrotuberous/sacrospinous ligaments.

Coccydynia (Tailbone Pain)

• Causes: Trauma (fall backward), childbirth, prolonged sitting, degenerative changes, tumor (rare).
• Pain with sitting, rising, defecation; tenderness on palpation.

Management

• Conservative: Donut cushion, NSAIDs, stool softeners, pelvic floor PT, ganglion impar block.
• Surgical (coccygectomy): Refractory cases; risk of wound complications, pelvic floor dysfunction.

Imaging

Dynamic X-rays (sit/stand) or MRI for instability, fracture, or mass.

The coccyx is small but clinically mighty—especially when it hurts.