Surgical anatomy of the nuchal muscles in the posterior cervicothoracic junction - Significance of the preservation of the C7 spinous process in cervical laminoplasty

Study Design. An anatomic study investigated the attachment of the nuchal muscles to the spinous process. Objective. To investigate the anatomic details of the attachment of the nuchal muscles to the spinous process, and which muscles are spared, and to what extent, when the C7 spinous process is preserved in the cervical laminoplasty. Summary of Background Data. In previous studies, it was reported that the incidence of postoperative axial pain was lower in C3 - C6 laminoplasty than in C3 - C7 laminoplasty, emphasizing the effectiveness of the former procedure where discission of the nuchal muscles that are attached to the C7 spinous process is avoided. However, there have been no detailed anatomic studies of the attachment of the nuchal muscles to the spinous process at the cervicothoracic junction. Methods. The anatomy of the speculum rhomboideum of the trapezius, rhomboideus minor, rhomboideus major, serratus posterior superior, splenius capitis, and splenius cervicis to the spinous processes of the cervicothoracic junction were studied using 50 cadavers. Results. The possibility of total discission of the speculum rhomboideum of the trapezius was 0% with C3 - C6 laminoplasty and 18% with C3 - C7 laminoplasty. More than 50% preservation of the speculum rhomboideum of the trapezius is possible in 72% in C3 - C6 laminoplasty and 16% in C3 - C7 laminoplasty. In C3 - C7 laminoplasty, the possibility of partial preservation of the rhomboideus minor, serratus posterior superior, and splenius capitis at the spinous process was 0%, 66%, and 29%, respectively. The rhomboideus major in 16% and the splenius cervicis in 56% could be completely preserved without partial discission of the muscle attachment. On the other hand, in C3 - C6 laminoplasty, the muscles that were spared without complete discission of the muscular attachment at the spinous process were the rhomboideus minor in 35%, the serratus posterior superior in 100% and the splenius capitis in 67%. The rhomboideus major in 76% and the splenius cervicis in 80% were completely spared without partial discission of the muscular attachment. Conclusion. The current study confirmed that C3 - C6 laminoplasty in which the C7 spinous process is preserved reduces invasion of the nuchal muscles.