Semispinalis capitis action includes which of the following?

Semispinalis capitis action includes which of the following?

• A. Flexes the head
• B. Lateral flexion of the neck
• C. Extends the head and neck; rotates to the opposite side
• D. Stabilizes the occipital bone

Answer: (C)

Semispinalis capitis works as part of the transversospinalis group, with fibers running obliquely from the transverse processes up to the occipital bone. When both sides contract, these fibers pull the occipital region backward, extending the head and neck. When a single side contracts, the same oblique pull causes rotation of the head to the opposite side because the line of pull crosses from a lateral origin to a medial insertion on the skull. So the primary actions are extending the head and neck and rotating the head to the opposite side, which is why the best choice is that combination. Flexion is handled by other muscles, and while the semispinalis capitis can contribute to stabilization, its defining actions are extension and contralateral rotation.

Semispinalis capitis works as part of the transversospinalis group, with fibers running obliquely from the transverse processes up to the occipital bone. When both sides contract, these fibers pull the occipital region backward, extending the head and neck. When a single side contracts, the same oblique pull causes rotation of the head to the opposite side because the line of pull crosses from a lateral origin to a medial insertion on the skull. So the primary actions are extending the head and neck and rotating the head to the opposite side, which is why the best choice is that combination. Flexion is handled by other muscles, and while the semispinalis capitis can contribute to stabilization, its defining actions are extension and contralateral rotation.