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Spinal Anatomy Notes

Terms in this set (13)

- Function: Support weight of head and protects the nerves that come from the brain to the rest of the body (~10 - 13 lbs). This region is very delicate as it houses the spinal cord that sends messages from the brain to control all aspects of the body, while it is also very strong and flexible (allowing movement in all directions). Vertebral openings (vertebral foramen) in the cervical spine provide a passageway for vertebral arteries to pass and ensure proper blood flow to the brain. These openings are present only in the vertebrae of the cervical spine.
- 7 pairs numbered from C1 to C7 that get smaller as they get closer to the base of the skull. The lower vertebrae need to be bigger to support the extra loads from above. Note all cervical vertebrae are smaller than the thoracic vertebrae (and the largest vertebrae are in the lumbar spine or lower back).
- The cervical vertebrae have cylindrical bones that lie in front of the spinal cord and stack up one on top of the other to make on continuous column of bones in the neck.
- At each level, the vertebrae protect their segment of the spinal cord and work with muscles, tendons, ligaments, and joints to provide a combination of support, structure, and flexibility to the neck.
- Most of the rotation of the cervical spine comes from the top two segments.
- Atlas (C1) allows for nodding or "yes" motion of the head. This is the only cervical vertebra to not have a vertebral body. It is shaped more like a ring. The atlas connects to the occipital bone above to support the base of the skull. This connection is the atlanto-occipital joint. About 50% of the head's forward/backward range of motion occurs at this joint.
- Axis (C2), allows for nodding or "no" motion of the head. This vertebra has a large bony protrusion (the odontoid process) that points up from its vertebral body, and fits into the ring-shaped atlas above it. The atlas is able to rotate around the axis, forming the atlanto-axial joint. About 50% of the head's rotation occurs at this joint.
- Typical vertebrae (C3, C4, C5, and C6): Called typical because they share the same basic characteristics with most of the vertebrae throughout the spine.
- Vertebral body: Cylindrical-shaped, thick part at the front of the bony vertebra.
- Vertebral arch: This bony arch wraps around the spinal cord toward the back and consists of two pedicles (a small stalk-like structure connecting an organ or other part to the human or animal body) and two laminae (part of the vertebral arch that forms the roof of the spinal canal).
- Facet joints: Each vertebra has a pair of facet joints, also known Zygapophysial joints (Z-joints). These joints are located between the pedicle and lamina on each side of the vertebral arch; they are lined with smooth cartilage to enable limited movement between two vertebrae. The small ranges of motion between the two vertebrae can add up to significant ranges of motion for the entire cervical spine in terms of rotation, forward/backward, and side bending.
- Most of the flexion/extension movement comes from C5-C6 and C6-C7 (each motion segment is named by the two vertebral bodies that are connected).
- Unique Vertebra (C7) or vertebra prominens usually has the most prominent spinous process. If one was the feel the back of the neck, the C7 vertebra's bony spinous process will stick out more than the other cervical vertebrae. C7 is the bottom of the cervical spine and connects with the top of the thoracic spine (T1) to form the cervicothoracic junction (referred to as C7 - T1). Not only is the spinous process significantly bigger than the vertebrae above it (it is also a different shape to better fit with T1 below). Due to its larger size and key location at the cervicothoracic junction, several more muscles connect to C7's spinous process compared to other cervical vertebrae.
- The joints of Luschka, also known as uncovertebral joints, are found between vertebral segments from C3 down to C7. These joints are comprised of two uncinate processes—one rising up from the top of each side of the vertebral body—that fit in indentations in the vertebral body above. The joints of Luschka help with the neck's forward and backward movements while also limiting the bending to either side. These joints are relatively small compared to facet joints—and unlike facet joints—these joints are not present at birth (they typically develop at age 10).
- Most neck pain relating to cervical vertebrae is the result of war and tear, not an injury.