The primary actions controlled by muscles innervated by the accessory nerve (CN XI) include?

The accessory nerve, also known as cranial nerve XI, is primarily responsible for innervating certain muscles that play a crucial role in movement and stability of the shoulders and head. Specifically, it innervates the sternocleidomastoid and trapezius muscles.

The actions controlled by these muscles include shoulder elevation, which allows for the lifting of the shoulders towards the ears, and head rotation, enabling the head to turn to the sides. These functions are vital for various daily activities, such as looking over one's shoulder or shrugging. The accessory nerve is unique in that it has both cranial and spinal components, with the cranial part aiding in the movement of the soft palate and pharynx, but its primary clinical significance relates to shoulder and head movement through the aforementioned muscles.

In contrast, the other choices relate to functions that are not primarily associated with CN XI, such as eye movements and blinking, facial expression and taste, or swallowing and speaking, which are predominantly governed by other cranial nerves.