On which aspect of the vertebrae are the demi-facets located?

• A. Transverse Process
• B. Vertebral Body
• C. Spinous Process
• D. Pedicle

Answer: (B)

The demi-facets are located on the vertebral body, specifically at the lateral aspects of thoracic vertebrae. These are small, smooth surfaces where the heads of the ribs articulate with the vertebrae. Each thoracic vertebra typically has two demi-facets (one on either side) to accommodate two ribs: one connecting to that vertebra and the other to the one above it. This arrangement allows for the attachment and movement of the ribs, which is crucial for respiration and maintaining the structure of the thorax.

While other choices like the transverse process and pedicle are important parts of the vertebrae, they do not have demi-facets. The transverse processes serve as attachment points for muscles and ligaments and have costal facets on certain vertebrae for rib articulation, but they are distinct from demi-facets. The spinous process is primarily a projection for muscle and ligament attachment, without any articulation role concerning ribs. The pedicle connects the vertebral body to other parts of the vertebra, contributing to the stability of the spinal column, but it also lacks the demi-facets.