"These muscles are enclosed by the prevertebral fascia and are directly anterior to the cervical vertebral bodies and deep to the prevertebral layer of the deep cervical fascia. They form the posterior boundary of the retropharyngeal space 1,2,3."
"All prevertebral muscles are supplied by anterior (ventral) rami of cervical spinal nerves (typically C1–C6, depending on the muscle) 4."