Which vertebra lacks both a body and a spinous process?

• A. C7 (Vertebra prominens)
• B. Axis (C2)
• C. T1 (First thoracic vertebra)
• D. Atlas (C1)

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the anatomy of the vertebrae. Vertebrae are the bones that make up the spinal column, and they typically consist of a body, a spinous process, and other structures such as transverse processes and vertebral foramen.
2. Step 2: Learn the unique features of the cervical vertebrae. The cervical vertebrae (C1-C7) are located in the neck region and have distinct characteristics compared to thoracic and lumbar vertebrae.
3. Step 3: Focus on the Atlas (C1). The Atlas is the first cervical vertebra and is unique because it lacks both a body and a spinous process. Instead, it has anterior and posterior arches that form a ring-like structure to support the skull.
4. Step 4: Compare the Atlas (C1) to other vertebrae. For example, the Axis (C2) has a body and a prominent odontoid process (dens), while C7 (Vertebra prominens) has a spinous process that is easily palpable. T1 (First thoracic vertebra) has a body and spinous process typical of thoracic vertebrae.
5. Step 5: Conclude that the Atlas (C1) is the correct answer because it is the only vertebra that lacks both a body and a spinous process, making it structurally unique in the vertebral column.