Figure 1: Anterior perspective of cervical bony anatomy. The C1-C7 vertebral bodies are demonstrated from the anterior perspective to allow the viewer to appreciate the articulations along the uncinate processes that compose the uncovertebral joints. The anterior perspective of the facet joints can also be appreciated while viewing between the transverse processes.

Figure 2: Posterior view of cervical spine. There are seven cervical vertebrae that connect the head to the thorax. The first two vertebrae are unique and given individual names; atlas (C1) and axis (C2). The seventh vertebra possesses a long spinous process, which serves as a helpful landmark, and is called the vertebra prominens. The atlas is largely a ring of bone lacking a body. Its large lateral masses are connected by anterior and posterior arches. The superior articular processes are deeply concave to receive the occipital condyles at the atlantooccipital joint. This "yes" joint produces anterior/posterior flexion and extension. The axis has a body from which projects superiorly the odontoid process or dens. This process is held in place behind the anterior arch of the atlas by the strong transverse ligament of the atlas. The atlantoaxial joint is the "no" joint where most of head rotation occurs. The remaining cervical vertebrae are characterized by having small bodies that are attached to the neural arch by short pedicles, transverse processes that contain transverse foramina, and spinous processes that are usually bifid. The first intervertebral disc is located between the bodies of C2 and C3. Each vertebral body subsequently is bound by discs as symphyseal joints and resist compressive forces. The facet joints are synovial joints between associated superior and inferior articular processes and facets. The cervical spine is the most mobile of the vertebral regions. The vertebral arteries first enter (usually) the transverse foramen of the C6 vertebra and ascend through the remaining vertebrae. After passing through the transverse foramen of the atlas, the artery curves around its lateral mass and rests in a groove along the superior border of the posterior arch before ascending into the posterior fossa through foramen magnum. (Image courtesy of AL Rhoton, Jr.)

Figure 3: Lateral view of skull and cervical spine. The forehead of the skull is formed by the frontal bone. This bone articulates posteriorly with the parietal bones along the coronal suture. The parietal bones articulate with the occipital bone posteriorly along the lambdoid suture. Lateral to the parietal bone is the temporal bone (at the squamosal suture) consisting in this view of the squamous part, tympanic part, and mastoid part. Projecting from the squamous part is the zygomatic process that unites with a process of the zygoma to form the zygomatic arch. Intervening between the squamous part of temporal and the frontal and zygomatic bones is the greater wing of the sphenoid. The inferior surface of the squamous part posteriorly has a depression, the mandibular fossa, for articulation with the mandibular condyle to form the temporomandibular joint. Posterior to this joint is the external auditory canal within the tympanic part of the temporal bone. Anteriorly, the nasal bones form the bridge of the nose and articulate laterally with the maxillae, which form the central part of the face and floor of the orbit. At the medial corner of the orbit is the lacrimal bone, which possesses a groove for the lacrimal sac. In the cervical region, the course of the vertebral artery is shown traversing the transverse foramina of the C6-C1 vertebrae. The lengthy spinous process of C7 (vertebra prominens) is a landmark element of the cervical spine. (Image courtesy of AL Rhoton, Jr.)

Figure 4: Posterolateral view of the right side of the atlas (C1) and axis (C2) vertebra. Several features of these vertebrae necessitate their having unique names. The atlas is essentially a ring of bone and lacks a body. It consists of an anterior and a posterior arch that join the lateral masses, from which extend the transverse processes containing a transverse foramen for passage of the vertebral artery and veins. After passing through the C1 transverse process, the vertebral artery courses around the lateral mass before penetrating the posterior atlantooccipital membrane and ascending through the foramen magnum into the posterior cranial fossa. Unique features of the axis include the odontoid process or dens that extends superiorly from its body behind the anterior arch of the atlas. The odontoid process is held in place here by ligaments, principally the transverse ligament of the atlas. The spinous process of the axis is commonly bifid. (Image courtesy of AL Rhoton, Jr.)

Figure 5: Posterosuperior view of the axis (C2) vertebra. The inferior surface of its body is united to the body of the third cervical vertebra by the first intervertebral disc. From its superior surface the odontoid process extends upward behind the anterior arch where it is held in place by ligaments. The superior articular facet of the axis slopes downward and laterally and articulates with the inferior articular facet of the atlas to form the atlanto-axial joint. The atlanto-axial articulation consists of three synovial joints: a single median atlanto-axial joint between the odontoid process and anterior arch and paired atlanto-axial joints between the lateral masses of each. The principal action at this joint is axial rotation. Extending posteromedially from each lateral mass are laminae that fuse in the midline at the bifid spinous process. Each transverse process contains a transverse foramen for the vertebral artery. (Image courtesy of AL Rhoton, Jr.)

Figure 6: Superior view of C3 vertebra. Cervical vertebrae C1 (atlas), C2 (axis), and C7 (vertebra prominens) are considered unique because of distinctive features. Vertebrae C3-C6 share similar features and are considered typical. The body is small relative to other regional vertebrae and attaches to the neural arch via short pedicles. The lateral masses contain superior and inferior articular processes which articulate with adjacent vertebrae. The transverse processes of cervical vertebrae are unique in that they contain foramina through which the vertebral arteries pass. The spinous processes, as shown, tend to be bifurcated, or bifid. The vertebral foramen is large to accommodate the cervical spinal cord. (Image courtesy of AL Rhoton, Jr.)

Figure 7: Posterior view of a segment of the thoracic spine demonstrating characteristic features of thoracic vertebrae. These include superior and inferior articular processes that possess facet surfaces covered by hyaline cartilage. Superior and inferior facets between subjacent vertebrae form synovial zygoapophyseal or facet joints that permit limited movement (rotation in the thoracic region). Bodies of thoracic vertebra are located anteriorly and are bound together by intervertebral discs. The vertebral canal is completed posteriorly by paired pedicles and laminae that fuse in the posterior midline to the spinous processes. The spinous processes in the thoracic region overlap one another like shingles on a roof and limit access to the vertebral canal. (Image courtesy of AL Rhoton, Jr.)

Figure 8: Posterior view of lower lumbar vertebrae and sacrum. The sacrum is an irregular triangular-shaped bone that is formed by the fusion of five sacral vertebrae. It unites with four bones: the fifth lumbar vertebra superiorly, the right and left hip bones laterally, and the coccyx inferiorly. The superior articular processes of the S1 vertebra articulates with the inferior articular processes of the L5 vertebra. The sacral canal is a continuation of the vertebral canal and conveys the sacral spinal nerves. It opens distally at the sacral hiatus, whose margins are formed by the two sacral cornua. The dural sac ends at the S2 level. Nerve roots of the fifth sacral nerve and the filum terminale externum exit the hiatus. The sacrum contains anterior and posterior sacral foramina where the anterior and posterior rami of sacral spinal nerves exit, respectively. The median sacral crest represents the remnants of the fused spinous processes and the lateral sacral crests form from fused transverse processes. The auricular surface is the site of articulation with the ilium (sacroiliac joint) and the sacral tuberosity located posterior to this is the attachment site of the posterior sacroiliac ligaments. (Image courtesy of AL Rhoton, Jr.)

Figure 9: Left lateral view of lumbar vertebrae and associated spinal nerves. The bodies of lumbar vertebrae are massive to support the body's weight. They are bound to one another by fibrocartilagenous intervertebral discs (symphysis joints). Zygoapophyseal or facet joints are synovial joints between superior and inferior articular processes between vertebrae. The intervertebral foramen is where spinal nerves exit the vertebral canal. The pars interarticularis is a region or bridge of bone between the superior and inferior articular processes. Defects in that region are referred to as spondylolysis. The transverse processes are directed posterolaterally and spinous processes of lumbar vertebrae are broad and blunt and project posteriorly and nearly horizontally. Both serve as muscle attachment sites for deep back muscles. In the lumbar spine, nerves exit inferior to the vertebra from which they are numbered.  (Image courtesy of AL Rhoton, Jr.)