Question #17
Which one of the following best describes a thoracic vertebra?
Each of the three groups of articulating vertebrae have specific features by which they can be identified:
Cervical: There are a total of 7 cervical vertebra, C1 (atlas) and C2 (axis) are atypical cervical vertebra. The remaining 5 typical vertebra have:
- small bifid spinous processes (except C7 which instead has a prominent spinous process with a tubercle. This is often easily palpated and is therefore known as the vertebra prominens)
- a body greater in size laterally than anteroposteriorly
- a foramen in each transverse process = foramen transversum (foramen transversarium or vertebrarterial foramen which contains vertebral vessels only). There are no foramen in the transverse processes of C7.
- Articulating facets are found in the coronal plane preventing rotation of the cervical spine from C3-C7. Most of this motion therefore occurs at the atlanto-axial joint.
- Small synovial joints laterally known as the uncovertebral joints.
- The vertebral foramen is large and triangular.
Thoracic: There are 12 thoracic vertebrae:
- articulate with the ribs (the first two and last two ribs articulate with their own vertebral bodies, the other ribs all articulate with their own vertebral body and the one above)
- heart shaped body
- two articular facets on the body in the vertical plane (not seen on other vertebra)
- Long spines slope inferiorly
- The vertebral foramen is circular (slightly larger at T11 and T12 to accommodate the presence of multiple cell bodies before the spinal cord terminates at the lower border of L1)
Lumbar: There are five lumbar vertebrae:
- kidney shaped body
- sagittal articulating facets
- large, quadrangular spines facing directly backwards
- the vertebral foramen is small and triangular