Anatomy, Head and Neck, Cervical Vertebrae

The spine, or vertebral column, is a segmental set of 33 bones and associated soft tissues that comprise the subcranial portion of the axial skeleton. It subdivides into five regions based on curvature and morphology: the cervical, thoracic, and lumbar spine, the sacrum, and the coccyx. There are seven, twelve, and five articulating vertebrae in the cervical, thoracic, and lumbar spine, respectively. These three regions, while somewhat similar in terms of bone morphology, variably balance spinal rigidity with flexibility and movement, and articulate in a particular fashion that contributes to the overall S-shaped curvature of the spine. Meanwhile, the sacrum and the coccyx are two sets of fused vertebrae at the caudal aspect of the spine that convey no motion. Five fused vertebrae typically form the sacrum, with four forming the coccyx.The cervical spine, comprised of seven cervical vertebrae referred to as C1 to C7, is divided into two major segments: the craniocervical junction (CCJ) and the subaxial spine. The CCJ includes the occiput and the two most cranial cervical vertebrae known as the atlas (C1) and the axis (C2). The subaxial spine includes the five most caudal cervical vertebrae (C3-C5). As a whole, the cervical spine is responsible for supporting the weight of the cranium and allowing motion of the head and neck.