Venous organization in the transverse foramen: dissection, histology, and magnetic resonance imaging

The content of the transverse foramen of the seventh cervical vertebra

In human anatomy, the vertebral artery, in its passage from the subclavian artery to the foramen magnum of the skull, enters the transverse foramina of the vertebral column generally at the level of the 6th cervical vertebra. Nevertheless, even though avoided by the vertebral artery, also the 7th cervical vertebra (C7) contains a transverse foramen. The content of this transverse foramen in C7 has been unclear, with different descriptions found in textbooks and in original literature. Here, we have revisited the content of the transverse foramen in C7 by macroscopic dissection of 32 human specimens. We found that the 7th transverse foramen never contained the vertebral artery. Instead, it enclosed in 35 % of the cases both vertebral vein and vertebral nerve, in 20 % of the cases only the vertebral nerve, in 11 % of the cases only the vertebral vein, and in 34 % of the cases it contained no macroscopically visible neurovascular structure at all but only adipose connective tissue.

A comprehensive review of the vertebral artery anatomy

BACKGROUND

The vertebral arteries (VA) play a critical role by supplying nearly one-third of the brain's blood flow, predominantly contributing to the posterior circulation. These arteries may need to be exposed in a various cranial and cervical procedures and offers access to investigate or treat vascular lesions by endovascular means related to the posterior circulation. Given its complex anatomy, which is subject to numerous variations, and its role in supplying vital brain regions, a thorough understanding of the VA's anatomy is paramount for any related procedure.

OBJECTIVE

To provide a comprehensive overview of vertebral artery anatomy and its relevance in contemporary clinical practice.

METHODS

Dissection of the entire vertebral artery length using cadaveric specimen, combined with a comprehensive literature review.

RESULTS

The vertebral artery can be subdivided into four segments. Each of these segments has its own unique topographic anatomy with its variations, anastomoses, and significance in surgery.

CONCLUSION

As surgical and endovascular techniques continue to evolve with technological improvements, we are now more equipped than ever to manage complex lesions involving the VA. However, with its increasingly complexity comes the necessity for a deeper and more comprehensive understanding of the VA. Possessing the detailed knowledge of the VA is vital for the successful execution of any procedure involving it.

The Feasibility of Anterior Occipital Condyle Screw for the Reconstruction of Craniovertebral Junction: A Digital Anatomical and Cadaveric Study of a Novel Technique

Background

Anterior occipital condyle screw (AOCS) could be a feasible alternative technique for occipitocervical fusion for reconstruction of craniovertebral junction. This study aimed to analyze the feasibility of AOCS.

Methods

The craniovertebral junction computed tomography (CT) scans of 40 adults were enrolled and imported into Mimics software. Then, the three-dimensional reconstruction digital model of craniovertebral junction was established to determine entry point, insertion angle, and screw’s trajectory. After AOCS insertion into ten human cadaver spine specimens, CT scans were performed to verify the location between screws and important structures.

Results

The optimal entry point was located caudally and medial to the ventral of occipital condyle. The optimal trajectory was in inclination angle (5.9°±3.4°) in the sagittal plane and divergence angle (26.7°±6.0°) in the axial plane with the screw length around 21.6±1.2mm. None of the screws invaded the hypoglossal canal and vertebral artery in any of the specimens.

Conclusion

AOCS fixation is a feasible, novel technique for anterior craniovertebral junction reconstruction, and it could be an effective alternative operation for anterior reconstruction with titanium mesh cage.

Spinal anastomosed remnant imprints of vertebral veins linking the transverse foramina: a case report of a novel anatomic variant of the cervical venous plexus

PURPOSE

Despite various postulated classifications attempting to simplify the complex angioarchitecture of the cervical spine, the nomenclature of spinal variants and lesions remains inconsistent. Knowledge of variations in the anatomy of the vertebral veins will assist in avoiding complications during neck surgery and procedures such as vertebroplasty. In addition, venous variants may act as a route for the spread of infection, emboli, or metastases. Therefore, we report a novel variant encountered at our institution in this case report.

METHODS

We coincidentally discovered an original anatomical variant of the cervical venous plexus linking the transverse foramina in a Saudi man.

RESULTS

We termed the variant "spinal anastomosed remnant imprints" (SARI), guided by the second edition of Terminologia Embryologica, a project of the Federative International Programme for Anatomical Terminology. This variant anastomoses with the vertebral veins at the same level, forming segmented osseous impressions. It shares a topographical relationship with the embryonic anterior cardinal veins, which normally regress in the prenatal period. We hypothesize that these intersegmental anastomosing veins do not always regress and may persist into adulthood, with individualized variations of the venous circulation.

CONCLUSION

This report highlights an important finding of interpersonal anatomical variation of veins in the cervical spine, discovered with the aid of advanced imaging to distinguish it from pathological conditions. This will be of assistance to radiologists, anatomists, and clinicians in decision-making and to surgeons in planning for neck surgery.

Microanatomical considerations for safe uncinate removal during anterior cervical discectomy and fusion: 10-year experience

Cervical radiculopathy from uncovertebral joint (UVJ) hypertrophy and nerve root compression often occurs anterior and lateral within the cervical intervertebral foramen, presenting a challenge for complete decompression through anterior cervical approaches owing to the intimate association with the vertebral artery and associated venous plexus. Complete uncinatectomy during anterior cervical discectomy and fusion (ACDF) is a controversial topic, many surgeons relying on indirect nerve root decompression from restoration of disc space height. However, in cases of severe UVJ hypertrophy, indirect decompression does not adequately address the underlying pathophysiology of anterolateral foraminal stenosis. Previous reports in the literature have described techniques involving extensive dissection of the cervical transverse process and lateral uncinate process (UP) in order to identify the vertebral artery for safe removal of the UP. Recent anatomical investigations have detailed the microanatomical organization of the fibroligamentous complex surrounding the UP and neurovascular structures. The use of the natural planes formed from the encapsulation of these connective tissue layers provides a safe passage for lateral UP dissection during anterior cervical approaches. This can be performed from within the disc space during ACDF to avoid extensive lateral dissection. In this article, we present our 10-year experience using an anatomy-based microsurgical technique for safe and complete removal of the UP during ACDF for cervical radiculopathy caused by UVJ hypertrophy.

Comparison of injection/dissection and injection/corrosion methods: example of vertebral veins in the transverse canal

PURPOSE

In order to contribute some new elements to the discussion on the organization of the vertebral veins inside the transverse canal, we compared two dissection techniques: injection/dissection and injection/corrosion. The aim of this study was to compare these two techniques to study the vertebral veins, and also to emphasize the importance of preserving specimens in anatomical museums.

METHODS

Using the injection/dissection technique, latex was injected into ten specimens, then the transverse canal was opened to expose the vertebral veins and their anastomoses. Using the injection/corrosion technique, altufix was injected into eight specimens that were afterwards plunged in sulfuric acid and washed daily until complete corrosion was obtained.

RESULTS

Both techniques showed concordant results. The vertebral veins were plexuous, located ventro-laterally to the artery and received constant metamerical branches at each level. The injection/dissection technique conserved the anatomical relationships allowing metamerical analysis of the vertebral veins. The injection/corrosion technique, however, failed to conserve these relationships but provided a precise visualization of smaller anastomosis.

CONCLUSIONS

By analyzing different aspects of the vertebral veins anatomy in the transverse canal, the two techniques complete each other. This study emphasizes the importance of preserving the anatomical preparations: in addition to the historical and cultural value of these preparations, they contain precious information that furthers our anatomical knowledge.