The superficial cervical fascia envelopes the sternocleidomastoid muscle. The nerve branches of the superficial cervical plexus pierce the superficial cervical fascia to become subcutaneous
The deep cervical fascia (synonym: the prevertebral fascia) contains all the deep cervical muscles and all the branches of the deep cervical plexus
The nerve branches of the superficial cervical plexus run in the fascial plane between the deep and superficial cervical fascia before they become subcutaneous
Deep cervical fascia (green arrow), superficial cervical fascia (cyan arrow), and the fascial plane between the deep and superficial cervical fascia (magenta arrow)
