Which of the following muscles is primarily responsible for head rotation?

Which of the following muscles is primarily responsible for head rotation?

• A. Deltoid
• B. Sternocleidomastoid
• C. Trapezius
• D. Levator scapulae

Answer: (B)

The sternocleidomastoid muscle is primarily responsible for head rotation due to its anatomical position and function. This muscle is located on each side of the neck and attaches at the sternum, clavicle, and mastoid process of the skull. When one sternocleidomastoid muscle contracts, it tilts the head toward the side of the muscle while rotating the face to the opposite side. This action facilitates the rotation of the head, making it essential for movements such as turning the head from side to side. The other muscles listed do have roles in neck or shoulder movement but do not primarily facilitate head rotation. The deltoid is mainly involved in shoulder abduction and movement of the upper arm. The trapezius primarily aids in shoulder elevation and movement of the scapula, with some involvement in neck movements but not specifically for rotation. The levator scapulae is mostly responsible for elevating the scapula and has limited involvement in head rotation. Therefore, the sternocleidomastoid's specific orientation and role in head movement establish it as the key muscle for head rotation.

The sternocleidomastoid muscle is primarily responsible for head rotation due to its anatomical position and function. This muscle is located on each side of the neck and attaches at the sternum, clavicle, and mastoid process of the skull. When one sternocleidomastoid muscle contracts, it tilts the head toward the side of the muscle while rotating the face to the opposite side. This action facilitates the rotation of the head, making it essential for movements such as turning the head from side to side.

The other muscles listed do have roles in neck or shoulder movement but do not primarily facilitate head rotation. The deltoid is mainly involved in shoulder abduction and movement of the upper arm. The trapezius primarily aids in shoulder elevation and movement of the scapula, with some involvement in neck movements but not specifically for rotation. The levator scapulae is mostly responsible for elevating the scapula and has limited involvement in head rotation. Therefore, the sternocleidomastoid's specific orientation and role in head movement establish it as the key muscle for head rotation.