Bone

We only have to know the structure of a 'typical' thoracic vertebra. And identify the spinal cord on MRI (how is this 'bone'….)

Structure of typical thoracic vertebra

Vertebrae have common unifying features:

• The vertebral body is a squat cylinder, wider at the top and the base, located at the anterior part of the vertebrae. In the 'typical' thoracic vertebra, the body contains two lateral demifacets for articulation with the ribs; the superior demifacet tends to be larger and articulates with the rib corresponding with the vertebra (ie. 2nd rib / 2nd vertebra, superior demifacet)
• The vertebral arch is formed by paired pedicles which project posteriorly from the body and paired lamina which unite posteriorly. At the junction of the lamina and the pedicle are the superior articular, inferior articular and transverse processes which are directed according to their name. The spinous process extends posteriorly and inferiorly from the union of the lamina.
• The pedicles attach directly to the vertebral body, usually from its superior part. They are narrow in the middle, forming the vertebral notch. The space between two adjacent vertebral bodies, pedicles and articular processes is the intervertebral foramen, the exit point for the spinal nerves.
• The lamina are wider than the pedicles, although relatively narrow for the typical thoracic vertebra. They unit posteriorly with the spinous process. The space between the spinous process, the lamina and the transverse process is the vertebral groove.
• The transverse process arise at the junction of the lamina and pedicle, and vary in size between vertebrae. For the typical thoracic vertebra, they are relatively large and contain the costal facet for articulation with the accompanying rib.
• The articular processes are projected superiorly and inferiorly for articulation with the adjacent vertebrae. The superior articular process for a thoracic vertebra is squat and the facet joint faces laterally and posteriorly. The inferior articular process is longer with its facet facing medial and anterior.

Identification of spinal cord on MRI

Most easily identified on T₂ imaging due to intense signal from the CSF.