Rami Of Cervical Spinal Nerves Research Articles

Surgical anatomy of the nerves and muscles in the posterior cervical spine: a guide for avoiding inadvertent nerve injuries during the posterior approach.

An anatomic study investigated the cervical dorsal rami and major cervical paravertebral muscles. 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. No detailed anatomic studies of the nerves and the muscles in the posterior neck useful for the posterior approach have been reported previously. 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. 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. 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.

Virally Mediated Misexpression of Hoxc-6 in the Cervical Mesoderm Results in Spinal Nerve Truncations

Members of theHoxgene family appear to regulate anterior–posterior (A–P) regionalization in embryos. Genetic manipulation of numerousHoxgenes in the developing trunk region of vertebrates results in changes in the morphology of individual vertebrae. We have used virally mediated, targeted misexpression to ectopically express the Hoxc-6 protein in chick embryos.Hoxc-6has an anterior border of expression at the cervical–thoracic transition in tetrapods. Misexpression of this gene in the cervical mesoderm of chick embryos results in dramatic truncations of the ventral rami of cervical spinal nerves in the infected region. These data point to a role forHoxc-6in axon guidance, and suggest that in addition to regulating proliferative rates,Hoxgene expression provides positional information utilized in producing domain-specific extracellular signals.

The efferent supply of the trapezius muscle: a neuroanatomic basis for the preservation of shoulder function during neck dissection.

The hypothesis that there is an alternative motor input to the trapezius muscle through cervical spinal nerves is evaluated through a review of the literature and through experimental studies performed by the author. Electrophysiologic testing of the spinal accessory nerve and of the ventral rami of the cervical spinal nerves was performed in cats and humans. These studies indicated that motor potentials recorded in the trapezius muscle after stimulation of the ventral rami of cervical spinal nerves in general represented the spread of current to the contiguous portions of the spinal accessory nerve or directly to the trapezius muscle. Rarely did there seem to be evidence of motor innervation to the upper and lower trapezius by fibers conveyed by the ventral rami of cervical spinal nerves. The predominant motor input to the trapezius muscle is through the spinal accessory nerve. Subjective evaluation, objective strength testing, and electromyographic evaluation were performed on patients who had undergone neck dissections. Three types of neck dissection were employed. These were modified neck dissection with preservation of the spinal accessory nerve, radical neck dissection with sacrifice of the spinal accessory nerve, and reconstruction using a cable graft and classical radical neck dissection. Regarding all of the methods of evaluation and comparison, the patients who retained function of the spinal accessory nerve in the postoperative period fared better than those who had a classical radical neck dissection with sacrifice of the spinal accessory nerve. This again supports the concept that the most important and predominant motor supply to the trapezius muscle is through the spinal accessory nerve. All of this information was used to construct a model of the spinal portion of the accessory nerve and of the innervation of the trapezius muscle. The clinical implications of this model are stated.