Which vertebra lacks a spinous process but has an anterior and posterior arch with tubercles?

• A. C7
• B. C1
• C. C3
• D. T1

Answer: (B)

Recognizing atlas anatomy helps explain this: the first cervical vertebra is ring-shaped and unique in lacking a vertebral body and a spinous process. It consists of an anterior arch and a posterior arch connected by lateral masses, and each arch has a midline tubercle. This configuration—with both arches bearing tubercles and no spinous process—fits the description perfectly. The other options have typical vertebral features: a vertebra with a noticeable spinous process like C3, or the long spinous process of C7, or a thoracic vertebra with rib-related facets. Therefore, the atlas is the one that matches.