The spine, composed of 24 vertebrae, one sacrum, one coccyx, and two vertebrae connected by the iliac crest, forms the central axis of the human body. It supports the skull above and connects to the girdle below. It enables the body to perform activities such as flexion, extension, and rotation, while maintaining balance. Viewed from the side, the spine resembles a double S-shape; these curves provide optimal support for external forces such as impacts and jumps. Viewed from the rear, a healthy spine looks like a straight rod.

The spine is composed of 24 vertebrae, one sacrum, one coccyx, and two vertebrae connected by the iliac crest, forming the central axis of the human body. It supports the skull above and connects to the girdle below. It enables the body to perform activities such as flexion, extension, and rotation, while maintaining balance. Viewed from the side, the spine resembles a double S-shape; these curves provide optimal support for external forces such as impacts and jumps. Viewed from the rear, a healthy spine looks like a straight rod.

The overall view of the spine is composed of frontal, posterior, and lateral views. The function of the spine is to support the trunk and protect the spinal cord. The adult male spine is approximately 70 cm long, while the female spine is slightly shorter, at about 60 cm. Its length can vary slightly depending on posture; when lying down, it can be about 2-3 cm longer than when standing, due to the compression of the intervertebral discs during standing. The total thickness of the intervertebral discs is about one-quarter of the total length of the spine. In older adults, the intervertebral discs thin due to changes in collagen composition, vertebral bodies widen and decrease in height due to osteoporosis, and the thoracic and cervical curvatures increase due to decreased spinal muscle dynamics. These changes all directly contribute to a decrease in the length of the spine in the elderly.

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