Which statement is true concerning the scalenes muscles?

The correct response highlights that the scalenes muscles are indeed innervated by the cervical plexus. The scalenes are a group of three muscles located in the lateral neck—anterior, middle, and posterior scalene. This innervation is crucial for their function, as the cervical plexus, which is formed by the ventral rami of the first four cervical nerves (C1-C4), supplies the motor nerves necessary for muscle contraction.

In addition to their role in innervation, the scalenes perform functions related to respiration. They assist in elevating the first and second ribs during inhalation, often categorized as accessory muscles of breathing. Furthermore, when the scalenes contract on one side, they can contribute to neck rotation; however, they primarily produce contralateral rotation rather than ipsilateral.

Understanding these aspects emphasizes the importance of the cervical plexus in supporting scalene muscle function, their contribution to breathing, and their action in neck movement. This knowledge is foundational for studying muscular anatomy and physiology in relation to movement and respiratory mechanics.