The Fertebral Column In Adults

ANATOMY OF THE SPINE

The vertebral column in an adult is composed of 33 bony vertebrae divided into five regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal. Significant flexibility is evidenced only at the level of the upper 25 vertebrae. In adult the 5 sacral vertebrae fuse together to form the sacrum, and later in adult life the 4 coccygeal vertebrae fuse together forming the coccyx. The lumbosacral angle is the angle formed at the junction of the long axes of the lumbar spinal vetebrae and the sacrum. The vertebrae gradually become larger going down to sacrum and then become progressively smaller toward the tip of the coccyx. The vertebrae reach maximum size just above the sacrum, which transfers the weight to the pelvic girdle at the sacro-iliac joints. The vertebral column shows some degree of flexibility because the vertebrae are separated by flexible intervetebral discs. The 25 cervical, thoracic, lumbar, and first sacral vertebrae also articulate at synovial facet joints, which enable and confine the flexibility of the vertebral column. Although the movement between two adjacent vertebrae is somehow limited, in accumulation the overall movement of the vertebral column shows a remarkably significant

The synovial joints between the superior and inferior articular processes on adjacent vertebrae are termed the facet joints (also known as zygapophysial joints or Z-joints ). They permit simple gliding movements. The movement of the lumbar spine is largely confined to flexion and extension with a minor degree of rotation (see the image below). The region between the superior articular process and the lamina is the pars interarticularis. A spondylolysis occurs if ossification of the pars interarticularis fails to occur.