Topographic anatomy of the posterior ramus of thoracic spinal nerve and surrounding structures.

STUDY DESIGN: Cadaver dissection. OBJECTIVE: To examine the potential points of spinal nerve entrapment and the articular branches in the thoracic spine. SUMMARY OF BACKGROUND DATA: Despite many cadaver studies focused on the cervical and lumbar spinal nerves, detailed anatomy of the thoracic nerve branches is missing from the viewpoint of painful neuropathy on the thoracic region. METHODS: A total of 120 pairs of thoracic spinal nerves out of 10 donated cadavers were dissected. Detailed anatomy of the posterior ramus and medial/lateral branches and their fine branches in the entire thoracic region was investigated by both macroscopic and stereomicroscopic dissections. RESULTS: The posterior ramus of the thoracic nerve passed through the narrow space between the bony structures and adjacent fibrous tissue. It is sent to the first branch, which is called "the descending branch," before bifurcating into medial and lateral branches. The medial branch runs posterolaterally, then turns medially along the edge of multifidus, and passes between that and semispinalis, whereas the lateral branch runs underneath the intertransverse ligament. Both medial and lateral cutaneous branches penetrated the thoracolumbar fascia, and the medial cutaneous branch penetrated the tendinous portion of back muscles. CONCLUSION: Several points might be listed as potential sites of entrapment along the course of the posterior ramus of the thoracic nerve and its branches, leading to the cause of thoracic back pain. In addition, the articular branch entering the facet (zygapophyseal) joint originated from the descending branch, which was the first branch of the posterior ramus.

Age-related changes in histogram pattern of anterior horn cells in human cervical spinal cord.

The purpose of the present study was to clarify age-related changes in histograms of spinal anterior horn cells. The study examined Rexed lamina IX of the C7 spinal cord segment in 22 men who had died of non-spinal disease (age range, 0-85 years). First, we confirmed that the size of nucleoli exhibited a linear relationship to the diameter of spinal anterior horn cells by preparing histograms of nucleoli. Second, this formula was used to create histograms of cervical anterior horn cells. Results were as follows: (i) diameter of nucleoli ranged from 2.0 microm to 6.0 microm; (ii) in each subject, no changes were seen in histogram patterns among ventral, intermediate, dorsal and overall sections; (iii) at < or =20 years of age, histograms displayed a single peak for the diameter of nucleoli at about 4.0-4.5 microm; (iv) at 21-60 years of age, histograms displayed two peaks, at about 3.5-4.0 microm and 5.0-5.5 microm; and (v) at 61-85 years of age, histograms displayed a single peak at about 5.0-5.5 microm.

Computer-assisted measurement of the size of ossification in patients with ossification of the posterior longitudinal ligament in the cervical spine.

BACKGROUND: Progression of ossification of the posterior longitudinal ligament in patients may lead to serious neurological deterioration. A government-funded study group established a manual method of measurement on plain radiographs to detect progression of the ossified lesion. However, this method did not gain wide acceptance because it was time-consuming and complicated, for which drawings of many lines and points are required. We have applied a computer-assisted measurement system to this task and have evaluated inter- and intraexaminer reliability, showing that it is quicker to use and more accurate than the manual method. METHODS: Eight board-certified spine surgeons, acting as the examiners, measured the sizes of the ossified lesions on nine lateral cervical spine radiographs using the computer-assisted measurement system. Following insertion of digitized radiographic image data into a computer, the corners of the vertebral bodies on the displayed images are marked by the examiners, and the software automatically sets reference lines and points. The examiners identify upper, lower, and posterior margins of the ossified lesions, and the software calculates the dimensions of the ossified lesions. Data obtained from eight examiners for length and thickness underwent rigorous statistical analysis by calculating the intraclass correlation coefficients with 95% confidence intervals (CIs) to determine interexaminer reliability and Pearson's correlation coefficients between the two measurements by the same examiner to determine intraexaminer reliability. RESULTS: The intraclass correlation coefficients were 0.927 and 0.968 with 95% CIs of 0.883-0.955 and 0.956-0.978 for measurements of length and thickness, respectively, of the ossified lesions. The Pearson's correlation coefficients for the two measurements by the same examiners were 0.943-0.985 for length and 0.957-0.991 for thickness. CONCLUSIONS: The inter- and intraexaminer reliability using this measurement system was excellent. The method can detect progression of ossification of the posterior longitudinal ligament (OPLL) on plain radiographs with high precision and could become a standard method for measuring the size of OPLL.

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

STUDY DESIGN: 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. SUMMARY OF BACKGROUND DATA: 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.

Anatomically correct reduction and fixation of a Tile C-1 type unilateral sacroiliac disruption using a rod and pedicle screw system between the S1 vertebra and the ilium: experimental and clinical case report.

We have developed a new surgical technique for the treatment of Tile C-1 type sacroiliac disruption. We tried this procedure first in a cadaveric specimen and then applied it to a clinical case. We used the Texas Scottish Rite Hospital (TSRH) rod and pedicle screw system to insert one screw into the S1 vertebra without using an image intensifier and the other screw into the bone marrow of the ilium from the posterosuperior iliac spine. A straight rod was connected between the two screws by using a manipulator to attempt to reduce and fix the sacroiliac disruption. The combined pubic symphysis diastasis could be simultaneously reduced and fixed by using a plate through another incision, resulting in anatomically correct reconstruction of the pelvic ring. In this procedure, the alignment of the sacroiliac joint can be reversibly and directly changed during reduction and fixation. The sacroiliac joint can be strongly fixed because the screws can be freely inserted into the intact portion of the pelvis and the adjacent lumbar spine, if necessary. Good reduction is obtained because direct compression force is applied to the fracture site. The posterior and anterior procedures can be simultaneously performed under the same lateral position.