aspects of each. Search engines such as PubMed and various germane textbooks were used, searching for salient chapters and terms such as the following: ligaments, neck, occipital, atlas, axis, connective tissues, anatomy, biomechanics, pathology, C-1, C-2, membrane, craniocervical junction, and craniovertebral junction. Biomechanics of CCJ The CCJ is composed of 2 major joints: the atlantooccipital and the atlantoaxial joints. These joints are responsible for the majority of the movement of the cervical spine and operate on different biomechanical principles. The
R. Shane Tubbs, Justin D. Hallock, Virginia Radcliff, Robert P. Naftel, Martin Mortazavi, Mohammadali M. Shoja, Marios Loukas and Aaron A. Cohen-Gadol
R. Shane Tubbs, Joshua Dixon, Marios Loukas, Mohammadali M. Shoja and Aaron A. Cohen-Gadol
Knowledge of the anatomy of the ligaments that unite the head with the neck is important to the clinician who treats patients with lesions in this region. Although the anatomy and function of these ligaments have been well described, those of the Barkow ligament (BL) have yet to be studied.
Via an anterior approach, 13 unembalmed adult cadavers underwent dissection of the craniocervical junction with special attention to the presence, anatomy, and function of the BL.
The BL was found in 92.3% of specimens. The attachment of each ligament onto the medial aspect of the occipital condyle was consistent and just anterior to the attachment of the alar ligaments. In 75% of specimens, there was some connection between the BL and the anterior atlantooccipital membrane. Connections between other adjacent ligamentous structures were not identified. The average width, length, and thickness of the BL were 4, 2.5, and 3.5 mm, respectively. With ranges of motion of the craniocervical junction, only extension of the atlantooccipital joint produced tension in the BL. The mean tension to failure of the ligament was 28 N. Statistical analysis revealed no significant difference in width, length, and thickness of the ligaments based on sex.
The BL was found in all but 1 of our specimens. This ligament appears to resist extension of the atlantooccipital joint and may be synergistic with the anterior atlantooccipital membrane. Interestingly, the function of this ligament as found in this study relies on the integrity of the transverse ligament. Knowledge of this ligament may aid in further understanding craniocervical stability and help in differentiating normal from pathological tissue using imaging modalities.
R. Shane Tubbs, Martin M. Mortazavi, Marios Loukas, Mohammadali M. Shoja and Aaron A. Cohen-Gadol
intracranial denticulate ligament (lig). Note the relationship between the course of the vertebral artery and its branches and the spinal accessory nerve (n) and first cervical rootlets to this ligament. a = artery. Used with permission from Clarian Health. Methods Ten fresh and 5 embalmed adult cadavers (30 sides) underwent dissection of the craniocervical junction. Nine specimens were male and 6 were female, and the age range of the individuals at the time of death was 49–101 years (mean 75 years). In the prone position, the specimens underwent removal of the
R. Shane Tubbs, Marios Loukas, Bulent Yalçin, Mohammadali M. Shoja and Aaron A. Cohen-Gadol
surgery or any pathological entity in the region of the craniocervical junction. The mean age of this group was 78 years (range 59–102 years). After the skin and the suboccipital muscles were removed, the C-1 and C-2 nerves were identified and dissected toward their origin from the spinal cord. The posterior arch of the atlas was removed with bone rongeurs for better visualization of the C-1 and C-2 nerves and the horizontal part of the VA. With scissors, a square incision was made in the dura mater to expose the spinal cord and all parts of the C-1 spinal nerve
R. Shane Tubbs, Martin M. Mortazavi, Marios Loukas, Anthony V. D'Antoni, Mohammadali M. Shoja, Joshua J. Chern and Aaron A. Cohen-Gadol
Occipital neuralgia can be a debilitating disease and may occur following operative procedures near the occipital and nuchal regions. One nerve of this region, the third occipital nerve (TON), has received only scant attention, and its potential contribution to occipital neuralgia has not been appreciated. Therefore, in the present study the authors aimed to detail the anatomy of this nerve and its relationships to midline surgical approaches of the occiput and posterior neck.
Fifteen adult cadavers (30 sides) underwent dissection of the upper cervical and occipital regions. Special attention was given to identifying the course of the TON and its relationship to the soft tissues and other nerves of this region. Once identified superficially, the TON was followed deeply through the nuchal musculature to its origin in the dorsal ramus of C-3. Measurements were made of the length and diameter of the TON. Additionally, the distance from the external occipital protuberance was measured in each specimen. Following dissection of the TON, self-retaining retractors were placed in the midline and opened in standard fashion while observing for excess tension on the TON.
Articular branches were noted arising from the deep surface of the nerve in 63.3% of sides. The authors found that the TON was, on average, 3 mm lateral to the external occipital protuberance, and small branches were found to cross the midline and communicate with the contralateral TON inferior to the external occipital protuberance in 66.7% of sides. The TON trunk became subcutaneous at a mean of 5 cm inferior to the external occipital protuberance. In all specimens, the cutaneous main trunk of the TON was intimately related to the nuchal ligament. Insertion of self-retaining retractors in the midline placed significant tension on the TON in all specimens, both superficially and more deeply at its adjacent facet joint.
Although damage to the TON may often be unavoidable in midline approaches to the craniocervical region, appreciation of its presence and knowledge of its position and relationships may be useful to the neurosurgeon who operates in this region and may assist in decreasing postoperative morbidity.
Jeffrey T. Jacob, Aaron A. Cohen-Gadol, Cormac O. Maher and Fredric B. Meyer
continued a distal route between the clivus and C-1 into the fourth ventricle and lodged in the pontomedullary junction. Fig. 1. Preoperative lateral CT scan of the skull base (upper) demonstrating the metal projectile lodged at the anterior craniocervical junction. There are minimally displaced clival and odontoid tip fractures. An axial CT scan revealing fractures of the left ethmoid sinuses (center) . This projectile most likely entered the left orbit and followed a course through the sinuses and oropharynx; it continued its distal path between the clivus
Charles Kulwin, Theodore H. Schwartz and Aaron A. Cohen-Gadol
through 3D graphic models. The purpose of this report is to familiarize the novice endonasal surgeon with a 6-step process for removing these meningiomas. Patient Selection Given the narrow corridor provided by this approach, patient selection is of utmost importance. In the sagittal plane, endoscopic endonasal surgery can reach from the frontal sinus down to the craniocervical junction. Anatomical limitations exist in the coronal plane and vary as one moves from a rostral to a caudal direction. 26 Likewise, although the endonasal corridor may be narrow at
R. Shane Tubbs, Nemil A. Shah, Brian P. Sullivan, Nicholas D. Marchase and Aaron A. Cohen-Gadol
The vertebral artery (VA) and its branches may be encountered during various neurosurgical procedures such as far lateral suboccipital approaches to the skull base and spinal operations. Therefore, a working knowledge of the distribution and significance of such VA branches may be advantageous to the surgeon. To date, quantitation of these branches is lacking in the literature.
The authors evaluated the branches of 20 VAs from 10 adult cadavers and assessed the distribution and surgical significance of the branches from the V2 and V3 segments.
In terms of target tissues, the VA branches encountered at the C1–2 level were most likely to be muscular, branches at C2–3 osseous, and those at C3–6 radicular. No radicular or medullary branches were identified arising from any V3 segment of the VA or C1–2 level of the V2 segment. The greatest concentration of branches per level was found arising from the V2 segment at C2–3. Posterior branches of the VA tended to be radicular or muscular, whereas anterior branches tended to be radicular or osseous. Lateral branches were most commonly radicular and medial branches tended to be osseous or muscular in nature. The largest branches of the VA originated from its V3 segment or the C2–3 part of its V2 segment. Rarely, branches to the extracranial glossopharyngeal and spinal accessory nerves were identified originating from the V3 and V2 segments of the VA, respectively.
Although seemingly diverse in their distribution, the branches of the V2 and V3 segments of the VA may follow a certain consistent arrangement. The potential for injury to neural branches of the VA is minimal at its V3 segment and the C1–2 portion of its V2 segment. Such knowledge may be of use to the neurosurgeon who operates in the neck and at the craniocervical junction.
Lorenzo Rinaldo, David S. Priemer, Alexander O. Vortmeyer, Aaron A. Cohen-Gadol, Daniel J. Brat, Anita Mahajan, Caterina Giannini and Terry C. Burns
C hordomas are rare neoplasms originating from notochordal remnants that typically occur along the axial skeleton. 26 Rostral to the craniocervical junction, chordomas are most commonly found within the bone of midline skull base structures, 42 although exclusively intradural chordomas have been previously reported. 1 In this paper we report an exceptionally rare case of a primary chordoma originating in the splenium of the corpus callosum. To the best of our knowledge, a chordoma in this location has not been previously described. Albeit extremely rare, this
R. Shane Tubbs, Jeffrey R. Lancaster, Martin M. Mortazavi, Mohammadali M. Shoja, Joshua J. Chern, Marios Loukas and Aaron A. Cohen-Gadol
, one report found that the persistence of the sphenooccipital synchondrosis, aggravated by the coexistence of basilar invagination, resulted in stenosis at the foramen magnum. 1 Among developmental and acquired craniocervical junction disorders, achondroplasia is the most commonly reported, with a frequently associated stenotic foramen magnum. 3 , 5–8 The AP and horizontal diameters of the foramen magnum have been found to be independent risk factors in these patients, who often need craniocervical decompression. 3 , 9 , 10 , 17 , 18 The configuration of the