Cervical uncinate process: an anatomic study for anterior decompression of the cervical spine

Cervical disc degeneration reduces distance between vertebral artery and surgical landmarks

PURPOSE

Anterior cervical decompression surgery exposes the vertebral artery to the risk of injury. This risk can increase if the natural course of the vertebral artery is altered. Therefore, this study evaluated if the distance between surgical landmarks and the vertebral artery decrease with the progression of cervical disc degeneration.

METHODS

This study analyzed 40 patients with cervical magnetic resonance imaging. We evaluated the distance between the uncinate process and the vertebral artery in axial-plane T2 weighted sequences of the cervical levels C3-C6. The cervical disc degeneration was graded according to the Pfirrmann- and Suzuki classification. The decrease of the distance was evaluated using a one-way ANOVA.

RESULTS

The distance between the uncinate process and the vertebral artery decreased with increasing disc degeneration (p ≤ 0.015). ROC analysis provided an acceptable area under the curve in both classifications for the detection of a vertebral artery to the uncinate process distance of zero. The presence of Pfirrmann grade V had a positive predictive value of 69% for the presence of contact between the uncinate process and the vertebral artery.

CONCLUSION

High-grade cervical disc degeneration according to the Pfirrmann- and the Suzuki classification decrease the distance between the uncinate process and the vertebral artery. High-grade disc degeneration therefore should raise the awareness of the surgeon for the loss of the distance between surgical landmarks and the vertebral artery. However, screening for high-grade disc degeneration alone cannot substitute the thorough evaluation of the anatomical course of the vertebral artery before surgery.

Analysis of the morphometric change in the uncinate process of the cervical spondylosis patients: A study of radiological anatomy

Purpose

Although there are many researches that focus on the relationship between the vertebral artery and uncinate process (UP), there were no publications concerning difference in the dimensions of the UP between the normal spine and degenerative spine, especially in Chinese patient. The purpose of this study is to determine the anatomic parameters that can be used as a guide for the procedure in intervertebral foramen decompression and for analysis of the morphometric change in the UP of the cervical spondylosis patients.

Methods

Forty patients from January 2016 to January 2019 were enrolled in this study. Three-dimensional computed tomography scans of the cervical spine were performed. The patients were subdivided into two groups which were nondegenerative cervical spine group (20 cases) and degenerative cervical spine group (20 cases). Six parameters concerning the height, width and angle of the UP were measured.

Results

In nondegenerative group, the average pedicle width was 3.63 mm–5.91 mm from C3 to C7. The average width of safe UP resection will be 3.06 mm at C3, 3.12 mm at C4, 3.28 mm at C5, 2.74 mm at C6 and 2.01 mm at C7. The average safe depth will be 6.04 mm at C3, 6.52 mm at C4, 7.61 mm at C5, 6.07 mm at C6 and 5.09 mm at C7. There are statistic difference between degenerative group and nondegenerative group, especially in the parameter minimum height of UP, maximum height of UP, medial border's distance of UP and later border's distance of UP.

Conclusion

In this retrospective study, our results suggest that for the Chinese patients who suffered from cervical spondylosis could be performed intervertebral foraminotomy decompression by resecting part of the UP. The safe range within the spinal canal was up to 6.73 mm of width between inferior vertebral endplate and superior vertebral endplate in the intervertebral space and up to 5.09 mm of depth from medial border of the UP to the lateral side atC3 to C7 without interfering the spinal nerve root and vertebral artery.

The translational potential of this article

Our study found the safe margin to perform intervertebral foramen decompression to the UP for the cervical spondylosis patients. This may help to improve safeness of the surgical procedure and provide data for future robotic surgery.

Morphometry of the Uncinate Process, Vertebral Body, and Lamina of the C3-7 Vertebrae Relevant to Cervical Spine Surgery

Objective

The cervical spine consists of 4 typical and 3 atypical vertebrae. The uncinate process is one of the unique features of the cervical vertebrae. Uncinectomy and uncoforaminotomy are widely used to decompress the nerve in the intervertebral foramen and to remove osteophytes from the uncinate process. Morphometric analyses of the uncinate process help spine surgeons obtain a 3-dimensional orientation for approaching the cervical spine with minimal risk to the surrounding vascular and neural structures. This study aims to analyze the morphometry of uncinate process of cervical vertebrae with relevant to cervical spine surgery.

Methods

Eighty dry adult cervical vertebrae were studied, and 11 parameters were measured. Seven parameters were paired and 4 were unpaired.

Results

The height of the uncinate process progressively increased from C3 to C6 and decreased at C7. The length of the uncinate process increased from C3 to C6–7. The width was greatest at C6 and smallest at C3. The vertebral body width and anteroposterior diameter gradually increased from C3 to C7. The parameters of the lamina also increased from C3 to C7.

Conclusion

Precise knowledge about the cervical vertebrae is useful for diagnosing both common and uncommon causes of symptoms and for choosing an appropriate approach. Thus, it helps to increase the success rate of cervical surgery.

Study of the Transverse Foramen in the Subaxial Cervical Spine in Korean Patients With Degenerative Changes: An Anatomical Note

Background/Aims

The purpose of this study was to provide anatomical data on the dimensions and location of the subaxial transverse foramen (TF) in relation to surgical landmarks routinely used during anterior cervical procedures.

Methods

A total of 116 patients who underwent preoperative computed tomography (CT) evaluations for degenerative cervical disease were enrolled. Axial and coronal CT images of the cervical vertebrae from C3 to C6 were analyzed to measure interforaminal distance, the TF distance from the anterior and posterior vertebral body margin, TF dimensions, and the TF medial margin from the tip and medial margin of the uncus. Comparative and correlative analyses were also performed according to age, body mass index (BMI), and sex.

Results

All measurement values in male patients were larger than those in their female counterparts. The interforaminal distance gradually increased from C3 to C6. The distance of the TF medial margin from the tip of the uncus was found be above approximately 3 mm in all vertebrae except C6. Correlation analysis revealed that age had a significant negative relationship with the transverse diameter of TF. In contrast, BMI had a significant positive correlation with interforaminal distance. Moreover, the distances of the TF medial margin from the tip and medial margin of the uncus showed strong negative correlations with age.

Conclusion

Useful morphometric data were obtained that may help the operating surgeon to avoid vertebral artery injury. The safe distance from the tip of the uncus to the TF medial margin was found to be approximately 3 mm, and this distance should not be violated during lateral decompression. In addition, this value may decrease with age.

Surgical Anatomy of the Longus Colli Muscle and Uncinate Process in the Cervical Spine

PURPOSE

There have been a few previous reports regarding the distances between the medial borders of the longus colli to expose the disc space. However, to our knowledge, there are no reports concerning longus colli dissection to expose the uncinate processes. This study was undertaken to assess the surgical relationship between the longus colli muscle and the uncinate process in the cervical spine.

MATERIALS AND METHODS

This study included 120 Korean patients randomly selected from 333 who had cervical spine MRIs and CTs from January 2003 to October 2013. They consisted of 60 males and 60 females. Each group was subdivided into six groups by age from 20 to 70 years or more. We measured three parameters on MRIs from C3 to T1: left and right longus colli distance and inter-longus colli distance. We also measured three parameters on CT: left and right uncinate distance and inter-uncinate distance.

RESULTS

The longus colli distances, uncinate distances, and inter-uncinate distances increased from C3 to T1. The inter-longus colli distances increased from C3 to C7. There was no difference in longus colli distances and uncinate distances between males and females. There was no difference in the six parameters for the different age groups.

CONCLUSION

Although approximate guidelines, we recommend the longus colli be dissected approximately 5 mm at C3-5, 6 mm at C5-6, 7 mm at C6-7, and 8 mm at C7-T1 to expose the uncinate process to its lateral edge.

Surgical Anatomy of the Uncinate Process and Transverse Foramen Determined by Computed Tomography

Study Design Computed tomography-based cohort study. Objective Although there are publications concerning the relationship between the vertebral artery and uncinate process, there is no practical guide detailing the dimensions of this region to use during decompression of the intervertebral foramen. The purpose of this study is to determine the anatomic parameters that can be used as a guide for thorough decompression of the intervertebral foramen. Methods Fifty-one patients with three-dimensional computed tomography scans of the cervical spine from 2003 to 2012 were included. On axial views, we measured the distance from the midline to the medial and lateral cortices of the pedicle bilaterally from C3 to C7. On coronal reconstructed views, we measured the minimum height of the uncinate process from the cranial cortex of the pedicle adjacent to the posterior cortex of vertebral body and the maximal height of the uncinate process from the cranial cortex of the pedicle at the midportion of the vertebral body bilaterally from C3 to C7. Results The mean distances from midline to the medial and lateral cortices of the pedicle were 10.1 ± 1.3 mm and 13.9 ± 1.5 mm, respectively. The mean minimum height of the uncinate process from the cranial cortex of the pedicle was 4.6 ± 1.6 mm and the mean maximal height was 6.1 ± 1.7 mm. Conclusions Our results suggest that in most cases, one can thoroughly decompress the intervertebral foramen by removing the uncinate out to 13 mm laterally from the midline and 4 mm above the pedicle without violating the transverse foramen.

Virtual pathology of cervical radiculopathy based on 3D MR/CT fusion images: impingement, flattening or twisted condition of the compressed nerve root in three cases

Background

There have been several imaging studies of cervical radiculopathy, but no three-dimensional (3D) images have shown the path, position, and pathological changes of the cervical nerve roots and spinal root ganglion relative to the cervical bony structure. The objective of this study was to introduce a technique that enables the virtual pathology of the nerve root to be assessed using 3D magnetic resonance (MR)/computed tomography (CT) fusion images that show the compression of the proximal portion of the cervical nerve root by both the herniated disc and the preforaminal or foraminal bony spur in patients with cervical radiculopathy.

Findings

MR and CT images were obtained from three patients with cervical radiculopathy. 3D MR images were placed onto 3D CT images using a computer workstation.

The entire nerve root could be visualized in 3D with or without the vertebrae. The most important characteristic evident on the images was flattening of the nerve root by a bony spur. The affected root was constricted at a pre-ganglion site. In cases of severe deformity, the flattened portion of the root seemed to change the angle of its path, resulting in twisted condition.

Conclusions

The 3D MR/CT fusion imaging technique enhances visualization of pathoanatomy in cervical hidden area that is composed of the root and intervertebral foramen. This technique provides two distinct advantages for diagnosis of cervical radiculopathy. First, the isolation of individual vertebra clarifies the deformities of the whole root groove, including both the uncinate process and superior articular process in the cervical spine. Second, the tortuous or twisted condition of a compressed root can be visualized.

The surgeon can identify the narrowest face of the root if they view the MR/CT fusion image from the posterolateral-inferior direction. Surgeons use MR/CT fusion images as a pre-operative map and for intraoperative navigation. The MR/CT fusion images can also be used as educational materials for all hospital staff and for patients and patients’ families who provide informed consent for treatments.

Anatomy and clinical significance of the uncinate process and uncovertebral joint: A comprehensive review

INTRODUCTION

The uncinate process and its associated uncovertebral articulation are features unique to the cervical spine. This review examines the morphology of these unique structures with particular emphasis on the regional anatomy, development and clinical significance.

MATERIALS AND METHODS

Five electronic databases were utilized in the literature search and additional relevant citations were retrieved from the references. A total of 74 citations were included for review.

RESULTS

This literature review found that the uncinate processes and uncovertebral articulations are rudimentary at birth and develop and evolve with age. With degeneration they become clinically apparent with compression of related structures; most importantly affecting the spinal nerve root and vertebral artery. The articulations have also been found to precipitate torticollis when edematous and be acutely damaged in severe head and neck injuries. The uncinate processes are also important in providing stability and guiding the motion of the cervical spine.

CONCLUSION

This review is intended to re-examine an often overlooked region of the cervical spine as not only an interesting anatomical feature but also a clinically relevant one.

Quantitative evaluation of the anatomical parameters for subaxial cervical spondylectomy: an anatomical study

OBJECT

The object of this investigation was to conduct a morphometric study in cadavers to determine anatomical structures, their relationships, and their morphometry for subaxial cervical spondylectomy.

METHODS

Forty sides of 20 cadavers were used for this study. Dissections were performed in 2 stages (anteriorly and posteriorly). Twenty-one morphometric measurements were performed for both sides of the C3-6 vertebrae. Data were analyzed statistically.

RESULTS

Morphometry of the laminas, tuberculum posterius, pedicle, corpus, foramen transversarium, and processus costalis were measured.

CONCLUSIONS

Detailed quantitative anatomical knowledge for operations requiring wide dissection and resection, such as cervical spondylectomy, lowers the morbidity rate.

Morphometrical study of uncinate processes and vertebral body of cervical spine

OBJECTIVE

The anatomical knowledge is the most important and has a direct link with success of operation in cervical spine surgery. The authors measured various cervical parameters in cadaveric dry bones and compared with previous reported results.

METHODS

We made 255 dry bones age from 19 to 72 years (mean, 42.3 years) that were obtained from 51 subjects in 100 subjects who donated their bodies. All measurements from C3-C7 levels were made using digital vernier calipers, standard goniometer, and self-made fix tool for two different cervical axes (canal and disc setting). We classified into 4 groups (uncinate process, vertebral body, lamina, and pedicle) and measured independently by two neurosurgeons for 28 parameters.

RESULTS

We analyzed 23970 measurements by mean value and standard deviations. In comparing with previous literatures, there are some different results. The mean values for uncinate process (UP) width ranged from 5.5 mm at C4 and 5 to 6.3 mm at C3 and C7 in men. Also, in women, the mean values for UP width ranged from 5.5 mm at C5 to 6.3 mm at C7. C7 was widest and C5 was most narrow than other levels. The antero-posterior length of UP tended to increase gradually from C3 to C6. The tip way, tip distance, and base distance of UP also showed increasing pattern from C3 to C7.

CONCLUSION

These measurements can provide the spinal surgeons with a starting point to address bony architectures surrounding targeted soft tissues for safeguard against unintended damages during cervical operation.

Analysis of the uncinate processes of the cervical spine: an anatomical study

Object

Although the uncovertebral region is neurosurgically relevant, relatively little is reported in the literature, specifically the neurosurgical literature, regarding its anatomy. Therefore, the present study aimed at further elucidation of this region's morphological features.

Methods

Morphometry was performed on the uncinate processes of 40 adult human skeletons. Additionally, range of motion testing was performed, with special attention given to the uncinate processes. Finally, these excrescences were classified based on their encroachment on the adjacent intervertebral foramen.

Results

The height of these processes was on average 4.8 mm, and there was an inverse relationship between height of the uncinate process and the size of the intervertebral foramen. Degeneration of the vertebral body (VB) did not correlate with whether the uncinate process effaced the intervertebral foramen. The taller uncinate processes tended to be located below C-3 vertebral levels, and their average anteroposterior length was 8 mm. The average thickness was found to be 4.9 mm for the base and 1.8 mm for the apex. There were no significant differences found between vertebral level and thickness of the uncinate process. Arthritic changes of the cervical VBs did not necessarily deform the uncinate processes. With axial rotation, the intervertebral discs were noted to be driven into the ipsilateral uncinate process. With lateral flexion, the ipsilateral uncinate processes aided the ipsilateral facet joints in maintaining the integrity of the ipsilateral intervertebral foramen.

Conclusions

A good appreciation for the anatomy of the uncinate processes is important to the neurosurgeon who operates on the spine. It is hoped that the data presented herein will decrease complications during surgical approaches to the cervical spine.

A safe approach to explore/identify the V2 segment of the vertebral artery during anterior approaches to cervical spine and/or arterial repairs: anatomical study

Object

The purpose of this study was to find a landmark according to which the surgeon can dissect the cervical spine safely, with the lowest possibility of damaging the vertebral artery (VA) during anterior approaches to the cervical spine or the VA.

Methods

The “safe zone” for each level of the cervical spine was described as an area where the surgeon can start from the midline in that zone and dissect the soft tissue laterally to end up on the transverse process and cross the VA while still on the transverse process. In other words, safe zone signifies the narrowest width of the transverse process at each level. In such an approach, the VA is protected from the inadvertent deep penetration of the instruments by the transverse process. The surgical safe zone for each level was the common area among at least 95% of the safe zones for that level. For the purpose of defining the upper and lower borders of the safe zone for each level, the line passing from the upper vertebral border perpendicular to the midline (upper vertebral border line) was used as a reference.

Cervical spines of 64 formalin-fixed cadavers were dissected. The soft tissue in front of the transverse process and intertransverse space was removed. Digital pictures of the specimens were taken before and after removal of the transverse processes, and the distance to the upper and lower border of the safe zone from the upper vertebral border line was measured on the digital pictures with Image J software. The VA diameter and distance from the midline at each level were also measured. To compare the means, the authors used t-test and ANOVA.

Results

The surgical safe zone lies between 1 mm above and 1 mm below the upper vertebral border at the fourth vertebra, 2 mm above and 1 mm below the upper vertebral border at the fifth vertebra, and 1 mm above and 2 mm below the upper vertebral border of the sixth vertebra. The VA was observed to be tortuous in 13% of the intertransverse spaces. There is a positive association between disc degeneration and tortuosity of the VA at each level (p < 0.001). The artery becomes closer to the midline (p < 0.001) and moves posteriorly during its ascent.

Conclusions

Dissection of the soft tissue off the bone along the surgical safe zone and removal of the transverse process afterward can be a practical and safe approach to avoid artery lacerations. The findings in the present study can be used in anterior approaches to the cervical spine, especially when the tortuosity of the artery mandates exposure of the VA prior to uncinate process resection, tumor excision, or VA repair.

Anterolateral approach to the cervical spine: major anatomical structures and landmarks. Technical note

OBJECT

The authors undertook a study to explore the topographic anatomical features seen during the anterolateral approach to cervical spine, anatomical variations, and certain landmarks related to the surgical procedure.

METHODS

The study was conducted in 30 fresh cadavers.

RESULTS

The common carotid artery bifurcation was mostly found at the level of C-4 (78%). The inferior belly of the omohyoid muscle was seen to cross the sternocleidomastoid muscle at the C5-6 disc level along the entire C-6 vertebral body. To reach the lower cervical region, the sacrifice of this muscle makes the procedure easier. The facial vein drained into the internal jugular vein mostly at the level of C3-4 (54%). The superior ganglion of the cervical sympathetic chain was located at the C-4 vertebra, but the location of the intermediate ganglion exhibited some variation. The vertebral artery entered the transverse foramen of C-6 in 27 cadavers (90%), the transverse foramen of C-7 in two cadavers (7%), and the transverse foramen of C-4 in one cadaver (3%). Because the inferior thyroid artery crossed the C6-7 interspace obliquely, the course of the inferior thyroid artery may complicate the procedure. The C-5 uncinate process was shortest and narrowest and had the greatest distance from the medial edge of the process to the anterior tubercle (p < 0.001).

CONCLUSIONS

Understanding the qualitative anatomy of this region not only improves the safety of anterior and anterolateral cervical spine surgery but also allows adequate decompression of neural elements and resolution of the other pathological processes of this region. In this fresh cadaveric study, our goal was to improve the approach and decrease the incidence of complications.

Small keyhole transuncal foraminotomy for unilateral cervical radiculopathy

Interbody fusion after anterior discectomy may lead to acceleration of degenerative changes at adjacent levels. Although the posterior approach preserves the motion segment, decompression of the nerve root is indirect if "hard disc prolaps" is the main cause. Recently, a technique of microsurgical anterior cervical foraminotomy for the treatment of radiculopathy with preservation of the segment mobility was published. In this study, we present this technique with several modifications.Thirteen patients - 5 men and 8 women with an average age of 49 years - with unilateral radiculopathy resistant to conservative treatment underwent microsurgical anterior foraminotomy via a small keyhole transuncal approach. The base of the uncinate process (UP) was directly drilled in the trajectory to the intervertebral foramen without destroying the disc tissue. The vertebral artery between the transverse process was not exposed. Furthermore, the functional anatomy of the uncovertebral joint remained largely intact. All patients experienced complete relief of radiating pain. A cervical collar was not used. Mean follow-up time was 19 months. The mobility of the operated segment was preserved in each patient. No instability of the cervical spine was seen. The microsurgical anterior foraminotomy via a small keyhole transuncal approach is safe, minimally invasive, and represents an effective method to treat unilateral cervical radiculopathy caused by disc prolaps and/or uncovertebral osteophytes. Additionally, the segment mobility is preserved and prevents the acceleration of degenerative changes at adjacent levels.

The V2 segment of the vertebral artery in anterior and anterolateral cervical spinal surgery: A cadaver angiographic study

OBJECTIVE

The second segment of the vertebral artery is under the risk of injury during anterior and anterolateral cervical spine procedures. To avoid such a risk, one needs to be familiar with the regional anatomy. The aim of this study was to measure the distance between the vertebral artery and the uncinate process, midline, and the medial side of the longus colli muscle using vertebral artery angiograms at the level of C6, C5, C4, and C3 vertebrae.

MATERIALS AND METHODS

In 12 human cadavers, the vertebral arteries were first irrigated with water. Then the arteries were filled with silicon and barium, and finally their angiographic images were obtained.

RESULTS

The transverse diameter of the vertebral artery was measured at C6, C5, C4, C3, and C2 level. The values on the left were bigger than the values on the right (p>0.05). The distance between the vertebral artery and the midline decreased from C6 (17.2+/-5.6mm on the right, 17.2+/-2.3mm on the left) to C3 (15.8+/-5.3mm on the right, 13.8+/-2.1mm on the left) (p>0.05). The distance between the apex of the uncinate process and the medial side of the vertebral artery was found to be longer at C4 (2.7+/-1.0 mm on the right, 2.2+/-1.0mm on the left) and C5 (2.5+/-1.1mm on the right, 2.5+/-1.0mm on the left) vertebra levels on the right side (p=0.339 at C4, p=0.862 at C5). The distance between the medial side of the longus colli muscle and the medial side of the vertebral artery was measured as 9.7+/-2.7 mm (9.5+/-2.9 mm on the right, 9.8+/-2.6mm on the left) at C6 level, 9.2+/-2.6mm (8.6+/-2.4mm on the right, 9.8+/-3.1mm on the left) at C5, 9.4+/-1.9 mm (9.2+/-2.1mm on the right, 9.5+/-2.0mm on the left) at C4, and 10.4+/-2.7 mm (10.5+/-3.0mm on the right, 10.1+/-2.6mm on the left) at C3 vertebra level. No significant difference was found between the right and the left (p>0.05). The angle between the vertebral artery and the midline was measured as 4.0+/-1.9 degrees on the right and 2.2+/-1.4 degrees on the left side (p=0.030).

CONCLUSION

It was considered that the values obtained could be useful in anterolateral and anterior cervical approaches in terms of evaluating the position of the vertebral artery and its relation to vertebral structures. It is also concluded that the risk of injury in upper subaxial cervical spine is higher than in the lower part of the subaxial cervical spine.

Anatomical projection of the cervical uncinate process in ventral, ventrolateral, and posterior decompressive surgery

OBJECT

The cervical uncinate processes (UPs), their variations, and the relationships between the neurovascular structures and surrounding bone were investigated in this anatomical study. The object of this study was to highlight the important surgery-related considerations associated with ventral, ventrolateral, and posterior decompressive surgery.

METHODS

Forty-nine adult C3-7 dry bone samples were used, and 10 measurements were obtained for each vertebra. The anterior measurements involved the cervical uncinate process (UP): height, width, length, distance between its tip and vertebral foramina, interuncinate process distance, sagittal angle with the superior margin of the vertebral body (VB), VB anteroposterior diameter, and VB width. Posterior measurements involved the vertical distance between the superior border of the lamina at the lamina-facet joint and the tip of the UP, as well as the horizontal distance between the medial-most border of the superior facet and the tip of the UP. All symmetrical structures were measured bilaterally. There were no statistically significant differences between right- and left-sided measurements in this series. The height of the UP increased gradually at each segmental level between C-3 and C-7. The width of the UP did not change with segmental level (5.0 mm at C-3 compared with 5.3 mm at C-7). On average, the length of the UP was relatively constant. The distance from the tip of the UP to vertebral foramina averaged 1 mm at the C2-3 level and 1.5 mm at the C5-6 level. Interuncinate distance and VB width gradually increased and were highly variable, which appeared to be related with osteophyte formation. There was a slight gradual increase from C-3 to lower segments, and it paralleled with the midline anteroposterior diameter of the same VB. The angle between the UP and the superior margin of the VB exhibited great variety. The posterior measurements decreased gradually from C-3 to C-7.

CONCLUSIONS

Based on the data obtained in this study, a surgeon is provided with a three-dimensional orientation as well as anatomical knowledge. This knowledge also allows for a more effective neurovascular decompression by minimizing the surgery-related complications.

Anatomic bases for anterior spinal surgery: surgical anatomy of the cervical vertebral body and disc space

Twenty adult cadaveric cervical spines were sectioned longitudinally through the midline to display longitudinal sections of the vertebral bodies and disc spaces from C3 to T1. Computer-assisted anatomic images were obtained for measurements of the disc spaces and vertebral bodies. Anteroposterior (AP) depth gradually increased from 16.56 +/- 2.21 mm at C3 to 19.32 +/- 2.30 mm at C7. Greater values of AP depth at the inferior endplate were found at C5 (20.75 +/- 2.87 mm) and C6 (20.56 +/- 2.31 mm) compared with the values at C3 (18.26 +/- 1.82 mm), C4 (19.27 +/- 2.88 mm) and C7 (19.21 +/- 3.22 mm). The AP depth at the superior endplate was greater than that at the inferior endplate. The height of the disc space was found to be lowest at the posterior disc space from C2-3 to C7-T1 (2.95 +/- 0.86 mm at C2-3, 2.78 +/- 0.93 mm at C3-4, 2.45 +/- 0.79 mm at C4-5, 2.92 +/- 0.64 mm at C5-6, 2.46 +/- 0.59 mm at C6-7, 2.93 +/- 1.05 mm at C7-T1), when compared to the height of the disc space at the anterior disc space from C2-3 to C7-T1 (4.07 +/- 0.85 mm at C2-3, 4.34 +/- 1.18 mm at C3-4, 3.95 +/- 1.37 mm at C4-5, 3.55 +/- 1.37 mm at C5-6, 3.55 +/- 0.76 mm at C6-7, 3.67 +/- 1.17 mm at C7-T1). The mid-axis of the disc space was situated at approximately 3 mm above the anterior midpoint of the annulus fibrosus at the level of the lower cervical spine. To reach the posterior portion of the disc space from the anterior midpoint of the annulus fibrosus, a 5 degrees cephalad angulation of the drill relative to the mid-axis of the disc space is necessary. All these original data from cadavers may be helpful during anterior approach for discectomy, vertebrectomy and anterior screw-plate placement.