College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Which of the following is considered an atypical vertebra?

1. C1

2. C2

3. C3

4. All of the above are atypical vertebrae

The correct answer is: C3

C3 is considered a typical vertebra rather than an atypical one. Atypical vertebrae generally exhibit unique structural characteristics that differentiate them from the majority of their type. To clarify: C1, also known as the atlas, and C2, known as the axis, are classified as atypical because they have distinct structural features that allow for significant mobility and support of the skull. C1 lacks a body, which is characteristic of typical cervical vertebrae, and instead has an anterior and posterior arch, enabling the nodding motion of the head. C2, with its odontoid process (or dens) allows for rotation of the skull on the vertebral column, which is also a unique feature not seen in typical cervical vertebrae. On the other hand, C3 has the standard features of cervical vertebrae, including a typical vertebral body, transverse processes, and spinous process, making it a classic example of a typical cervical vertebra, rather than an atypical one.