Which cervical vertebra is commonly injured from severe flexion or extension of the neck?

• A. C3
• B. C4
• C. C2
• D. C5

Answer: (C)

The cervical vertebra that is most commonly injured from severe flexion or extension of the neck is C2, also known as the axis. C2 is uniquely shaped with a bony projection called the odontoid process or dens, which allows for the pivoting motion of the head and neck. It is crucial in maintaining stability between the skull and the cervical spine.

In cases of extreme neck flexion or extension, such as during certain types of trauma (for example, car accidents or sports injuries), the mechanical stresses can lead to fractures or dislocations of the C2 vertebra. These injuries can be particularly dangerous, as they may compromise the spinal cord and lead to significant neurological deficits.

The other cervical vertebrae listed have different biomechanical functions and are typically less susceptible to the same types of injuries from flexion and extension forces as C2. While injuries can occur at the levels of C3, C4, or C5, C2 is particularly at risk due to its anatomical position and role in the cervical spine's range of motion.