Surgical anatomy of the nerves and muscles in the posterior cervical spine: a guide for avoiding inadvertent nerve injuries during the posterior approach.
METHODS
An anatomic study investigated the cervical dorsal rami and major cervical paravertebral muscles.


OBJECTIVE
To provide a detailed description of the cervical dorsal rami and important paravertebral muscles as a way of avoiding inadvertent injuries during the posterior approach.


BACKGROUND
No detailed anatomic studies of the nerves and the muscles in the posterior neck useful for the posterior approach have been reported previously.


METHODS
Running courses of the cervical dorsal rami of spinal nerves and the morphology of cervical major paravertebral muscles were studied using 14 cadavers. In four posterior approaches of cervical laminoplasty, subcutaneous facial exits of cutaneous nerves and the running course of the right C3 medial branches around facet joint were exposed for observation of living anatomy.


RESULTS
Every medial branch from the dorsal rami of the C3-C8 spinal nerves passed through an anatomic tunnel dorsolateral to the facet joint. The base of the tunnel was a bony gutter between neighboring facet joint capsules, and the roof was the tendon of the semispinalis capitis. In this tunnel, the medial branch had a little laxity in moving, and was assumed to be the most susceptible to iatrogenic injury during the operation. The semispinalis cervicis was composed with long muscle bundles. Each of these had only one or two innervating nerves from the dorsal rami of cervical spinal nerves. Cutaneous branches from the dorsal rami were found adjacent to every spinous process below the C2 spinous process in cadaveric studies. However, only two or three larger cutaneous nerves were discernible below the C5 or C6 spinous process in surgical approaches.


CONCLUSIONS
With the posterior approach to the cervical spine, a precise knowledge of the cervical dorsal rami anatomy and the innervating patterns of the paravertebral muscles is necessary for avoidance of inadvertent injuries to the nerves.
Zhang
Junwei
J
Department of Orthopedic Surgery, Saitama Medical Center, Saitama Medical School, Japan. cho@saitama-med.ac.jp
Tsuzuki
Nobuyuki
N
Hirabayashi
Shigeru
S
Saiki
Kunio
K
Fujita
Kazumasa
K
D000293:Adolescent; D000328:Adult; D000368:Aged; D002102:Cadaver; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000294:innervation; D005260:Female; D006801:Humans; D008297:Male; D019300:Medical Errors / Q000517:prevention & control; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D009333:Neck / Q000033:anatomy & histology* / Q000098:blood supply / Q000294:innervation; D009412:Nerve Fibers; D013131:Spine / Q000033:anatomy & histology* / Q000294:innervation