Cervical vertebrae

In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have 7 cervical vertebrae, with the only 3 known exceptions being the manatee with 6, the two-toed sloth with 5–6, and the three-toed sloth with 9. Scrollable computed tomography images of normal cervical vertebraePosition of cervical vertebrae (shown in red). Animation.Illustration of cervical vertebraeShape of cervical vertebrae (shown in blue and yellow). Animation.3D imageCervical vertebrae, lateral view (shown in blue and yellow)Vertebral columnVertebral columnX-ray of cervical vertebraeX-ray of cervical spine in flexion and extensionFirst cervical vertebra, or atlasSecond cervical vertebra, or epistropheus, from aboveSecond cervical vertebra, epistropheus, or axis, from the sideSeventh cervical vertebraPosterior atlanto-occipital membrane and atlantoaxial ligamentMedian sagittal section through the occipital bone and first three cervical vertebraeSection of the neck at about the level of the sixth cervical vertebraAnterior view of cervical spine showing the vertebral arteries along with the spinal nerves. See this in 3d here. In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have 7 cervical vertebrae, with the only 3 known exceptions being the manatee with 6, the two-toed sloth with 5–6, and the three-toed sloth with 9. In humans, cervical vertebrae are the smallest of the true vertebrae, and can be readily distinguished from those of the thoracic or lumbar regions by the presence of a foramen (hole) in each transverse process, through which the vertebral artery, vertebral veins and inferior cervical ganglion pass. The remainder of this article focuses upon human anatomy. By convention, the cervical vertebrae are numbered, with the first one (C1) closest to the skull and higher numbered vertebrae (C2–C7) proceeding away from the skull and down the spine.The general characteristics of the third through sixth cervical vertebrae are described here. The first, second, and seventh vertebrae are extraordinary, and are detailed later. The anterior tubercle of the sixth cervical vertebra is known as the carotid tubercle or Chassaignac tubercle. This separates the carotid artery from the vertebral artery and the carotid artery can be massaged against this tubercle to relieve the symptoms of supraventricular tachycardia. The carotid tubercle is also used as a landmark for anaesthesia of the brachial plexus and cervical plexus.