What is the function of cranial nerve 11 (accessory nerve)?

The accessory nerve, also known as cranial nerve 11, primarily functions in the motor control of specific muscles associated with head movement and shoulder elevation. It innervates two main muscles: the sternocleidomastoid and the trapezius.

The sternocleidomastoid muscle facilitates rotation of the head and flexion of the neck, allowing for turning the head from side to side. The trapezius muscle assists in elevating the shoulders, as well as in head and neck extension. This means that the accessory nerve is crucial for actions such as shrugging the shoulders and turning the head, making it essential for mobility and posture-related functions.

In contrast, the other options pertain to functions of different cranial nerves or bodily systems. Tongue movement is primarily controlled by cranial nerve 12 (hypoglossal nerve), taste sensation involves cranial nerves like 7 (facial nerve) and 9 (glossopharyngeal nerve), while control of heart rate is primarily regulated by the autonomic nervous system, specifically through the vagus nerve (cranial nerve 10).