tailbone

The tailbone, scientifically known as the coccyx, is the small triangular bone at the base of the vertebral column. It is located below the sacrum and typically consists of three to five coccygeal vertebrae that are fused or partly fused in adults. The coccyx articulates with the sacrum at the sacrococcygeal joint and is stabilized by several ligaments and by the attachments of pelvic floor muscles.

Anatomy and variation

The coccyx varies in size and shape among individuals. In adults it is usually about a few centimeters long and curves slightly forward. The coccygeal vertebrae may be fused to varying degrees, and there may be small intervertebral joints between them. The coccyx serves as an attachment point for muscles and ligaments of the pelvic floor, including the coccygeus and portions of the levator ani group, as well as connective tissues that form the anococcygeal raphe and support structures of the sacrococcygeal region. It also helps stabilize seating posture by providing leverage and a contact point for sitting.

Clinical significance

The coccyx can be a source of pain, a condition known as coccydynia, often following a fall onto the buttocks or prolonged sitting on hard surfaces. It is also noted during late pregnancy or in individuals with repetitive straining. Diagnosis is typically clinical, supported by imaging if needed. Treatment is usually conservative, including cushion use, nonsteroidal anti-inflammatory drugs, physical therapy, and adjustments to sitting posture. Persistent, severe cases may be treated with injections or, rarely, surgical removal of part or all of the coccyx (coccygectomy). Most coccygeal conditions improve with time and conservative care.