The terminal insertional segments and communications of the vertebral nerve in the human cervical region.

Twenty-four cadavers (48 sides) were used to clarify the terminal insertional segment and communications of the vertebral nerve in the cervical region under a surgical microscope. After displacing the prevertebral muscles (longus colli and longus capitis) laterally, the ventral parts of the transverse foramen of vertebrae (from C2 to C6) were removed, and the insertional segment and communicates of the vertebral nerve surrounding the vertebral artery were observed. The results showed: (1) the vertebral nerve ascended along the ventral or mediodorsal vertebral artery and terminated mainly at C3 (22/36 sides) but not terminated at C4 or C5 only; (2) the superficial communicates from the cervical sympathetic trunk ran in a proximal and distal direction when the fibers entered the anterior branches of the cervical nerves. The fibers running to the proximal direction communicated with the vertebral nerve in the part of transverse foramen; (3) motor and/or sensory rami supplying the prevertebral muscles, corpus vertebrae and intervertebral discs could pass through an "arched-shaped" fiber bundle on the ventral surface of the vertebral artery. In conclusion, the vertebral nerve and the fibers surrounding the vertebral artery could be considered as a stable deep pathway of cervical sympathetic nerves. The deep pathway (vertebral nerve and its branches) with the superficial pathways (cervical sympathetic trunk and its branches) formed a sympathetic nervous "plexus" in the cervical region. This sympathetic nervous "plexus" may be involved in the effects of cervical ganglionic blockade.