Coccyx

Illu vertebral column

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Coccyx, commonly referred to as the tailbone, is the final segment of the vertebral column in humans and certain other animals. Comprising three to five separate or fused vertebrae below the sacrum, the coccyx is a vestigial structure that remains as a remnant of a lost tail. Despite its reduced size and function in humans, the coccyx plays a significant role in the support and stability of the pelvic region, serving as an attachment site for various muscles, tendons, and ligaments.

Anatomy

The coccyx is typically made up of four vertebrae in humans, named the coccygeal vertebrae, which can be partially or completely fused. The number of coccygeal vertebrae can vary from three to five, with four being the most common configuration. The coccyx articulates superiorly with the sacral bone at the sacrococcygeal symphysis, a cartilaginous joint that allows for limited movement, primarily during childbirth.

Function

Although often considered a vestigial structure, the coccyx has several important functions. It serves as an attachment point for various muscles, ligaments, and tendons. Among these are the gluteus maximus, which extends the thigh at the hip; the levator ani, which supports the pelvic organs; and the coccygeus muscle, which assists in supporting the pelvic floor. The coccyx also plays a role in supporting the body when sitting, especially in a leaning back position.

Clinical Significance

Injury to the coccyx, commonly known as a coccyx or tailbone injury, can occur due to direct trauma, such as a fall onto the tailbone, or as a result of childbirth. Symptoms of a coccygeal injury include pain and tenderness at the base of the spine, which can be exacerbated by sitting or by any pressure on the area. Treatment for coccygeal injuries typically involves pain management, the use of cushions or pillows designed to relieve pressure on the coccyx, and, in rare cases, surgery.

Coccydynia is a condition characterized by chronic pain in the coccyx area. The pain associated with coccydynia can be severe and is often aggravated by sitting. The exact cause of coccydynia is not always clear, but it may arise from trauma, abnormal mobility of the coccyx, or the degeneration of the coccygeal vertebrae.

Evolutionary Perspective

The coccyx is considered a vestigial structure, a remnant of a longer tail present in our evolutionary ancestors. In some animals, the tail serves various functions, such as balance and communication. However, as humans evolved to walk upright, the need for a tail diminished, leading to the reduced form of the coccyx observed today.

See Also

• Vertebral column
• Sacrum
• Pelvis
• Coccydynia

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