The spine

Abstract

Evolution of human has led to morphological mutations in the spinal column because of its crucial role for maintaining erect posture. The principal functions of the spinal column are weight-bearing, movement, and protection. Spinal column consists of a total of 24 vertebrae (7 cervical, 12 thoracic, and 5 lumbar), 4 fused sacral, and 3 or 4 fused coccygeal segments. All the vertebrae are separated by intervertebral disc. Atlas and axis have different morphology from the subaxial cervical spine due to their special function in the craniocervical junction. Lateral masses of cervical vertebrae are thick bony structures that can be used during posterior instrumentation procedures as fixation points. Major morphologic differences of thoracic spine rise from the components of the thoracic cage. Pedicle morphologies and orientations change level to level in this region. Lumbar segments are quite larger than the cervical and thoracic segments. Ligamentous structures are crucial for proper stability of the spinal column. The main ligamentous structures of the spinal column are ligamentum nuchae, anterior longitudinal ligament, posterior longitudinal ligament, ligamentum flavum, facet capsule, interspinous ligament, and supraspinous ligament. The spinal column is surrounded by muscles, which mainly control movements and maintain the posture of the head and trunk. Some of them also support respiratory function. The spinal column is totally straight in the coronal plane and has physiological curvatures in the sagittal plane. The stability of the spinal column is primarily dependent upon the integrity of ligaments, discs, and bony structures. This concept is involved in the pathophysiology of many spinal disorders.