The atlas (C1) is the most superior (first) cervical vertebra of the spine and is located in the neck, directly under the skull. The atlas's chief peculiarity is that it has no body. It is ring-like and consists of an anterior and a posterior arch and two lateral masses. The atlas and axis are important neurologically because the brainstem extends down to the axis.
The axis is the second cervical vertebra (C2) of the spine, immediately posterior to the atlas. The axis' defining feature is its strong odontoid process (bony protrusion) known as the dens, which rises dorsally from the rest of the bone
The dens of the axis articulates with the anterior arch of the atlas, in doing so creating the medial atlanto-axial joint. This allows for rotation of the head independently of the torso. You can see the rotation here.
C3 till C5
These vertebrae are very much alike. they all have transverse foramen to guide the vertebral arteries and cervical veins.
The C6 looks different from the other cervical vertebrae of due to an additional posterior tubercle of the transverse process, but is actually the cervical vertebra that is most similar to those from other mammals.
The C7 doesn't have transverse foramina, the hole where the vertebral veins and arteries run through on the other cervical vertebrae.
T1 and T2
Even though the T1 and T2 look as if they are part of the neck, they can be distinguished by the fact that there are ribs attached.The T2 of the rat is very distinct because of the large spinous process.
Arteries and Veins
The vertebral arteries and veins not only supply the skull and brain with blood but also the vertebrae. Look at the way both the arteries and veins are led through the transverse foramen of the vertebrae.
The vertebral arteries are major arteries of the neck. Typically, the vertebral arteries originate from the subclavian arteries. Each vessel courses superiorly along each side of the neck, merging within the skull to form the single, midline basilar artery. As the supplying component of the vertebrobasilar vascular system, the vertebral arteries supply blood to the upper spinal cord, brainstem, cerebellum, and posterior part of brain.
The vertebral vein is formed in the suboccipital triangle, from numerous small tributaries which spring from the internal vertebral venous plexuses and issue from the vertebral canal above the posterior arch of the atlas. They unite with small veins from the deep muscles at the upper part of the back of the neck, and form a vessel which enters the foramen in the transverse process of the atlas, and descends, forming a dense plexus around the vertebral artery, in the canal formed by the transverse foramina of the upper six cervical vertebrae.
A ligament is the fibrous connective tissue that connects bones to other bones. In this overview you see the ligaments flava that "seal" the space between the Posterior arches of the vertebrae and the intertransvers ligaments that connect the transverse processes.
The intertransverse ligaments are ligaments that are placed between the transverse processes of the spine. In the cervical region they consist of a few irregular, scattered fibers that are often replaced by muscles. In the thoracic region they are rounded cords intimately connected with the deep muscles of the back. In the lumbar region they are thin and membranous. The intertransverse ligaments often blend with the intertransverse muscles. The function of the intertransverse ligaments is to limit lateral flexion of the spine.
The ligamenta flava (singular, ligamentum flavum, Latin for yellow ligament) are a series of ligaments that connect the ventral parts of the laminae of adjacent vertebrae. Each ligamentum flavum connects two adjacent vertebrae, beginning with the junction of the axis and third cervical vertebra, continuing down to the junction of the fifth lumbar vertebra and the sacrum.
An intervertebral disc (or intervertebral fibrocartilage) lies between adjacent vertebrae in the vertebral column. Each disc forms a fibrocartilaginous joint (a symphysis), to allow slight movement of the vertebrae, to act as a ligament to hold the vertebrae together, and to function as a shock absorber for the spine.
Articular capsules are the fibrous capsules that surround the vertebral facet or zygapophyseal joints. They are particularly thin and loose, attached to the margins of articular facets on adjoining articular processes. In the cervical region, capsules are longer and looser than the remaining spine, allowing for more range of movement.
The cervical nerves are the spinal nerves from the cervical vertebrae in the cervical segment of the spinal cord. Although there are seven cervical vertebrae (C1-C7), there are eight cervical nerves C1–C8. C1–C7 emerge above their corresponding vertebrae, while C8 emerges below the C7 vertebra. Everywhere else in the spine, the nerve emerges below the vertebra with the same name.
The transversospinalis muscle group is the deep layer of the intrinsic back muscles. These muscles lie between the transverse and spinous processes and are grouped by length of the fascicles, as well as region covered. The groups are rotatores, multifidus, and semispinalis. Only rotatores and multifidus are shown here.
The multifidus muscle is comprised of repeated bundles of short muscles that span one to five vertebral levels each. They are located on either side of the spine, attaching on the transverse and spinous processes. The muscle attaches onto all spinal vertebrae except the atlas. What you see here is just a sketch of them.
Rotatores occupy the third, or deep layer of the intrinsic back muscles. They are the deepest and shortest transversospinal muscles. What you see here is just a sketch of them.
The Neck Vertebrae of Rattus norvegicus
This app shows the neck vertebrae and a limited amount of the tissues surrounding them. click on the underlying tabs to see an explanation per tissue.
© 2021. Mieke Roth