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The Anatomy of Joints Related to Function
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
When lateral flexion is the primary motion, the reverse sequence explains the observed conjunct rotation (133). In these motions of rotation and lateral flexion at the occipitoatlantoaxial joints, the diverging lateral fibers of the membrana tectoria follow a roughly parallel course to the alar ligaments and may play a similar role in limiting these movements (133). Throughout the whole motion of rotation at these two levels, the alar ligaments remain under some degree of tension and the lateral location of the occiput is precisely maintained upon the atlantoaxial complex, while keeping the passive resistance to motion very small (139).
Neuroanatomy overview
Published in Michael Y. Wang, Andrea L. Strayer, Odette A. Harris, Cathy M. Rosenberg, Praveen V. Mummaneni, Handbook of Neurosurgery, Neurology, and Spinal Medicine for Nurses and Advanced Practice Health Professionals, 2017
Carolina Sandoval-Garcia, Daniel K. Resnick
The craniocervical region has an additional set of ligaments worth mentioning separately. Given the importance of maintaining stability while allowing for full mobility of the head in relationship to the rest of the body, one of the key ligaments in the occipitocervical junction is the cruciate ligament. The superior and inferior limbs that form this complex offer no significant support, but in turn, the transverse ligament is the strongest found in the cervical spine and maintains the odontoid process anteriorly against the dorsal surface of the anterior arch of C1 while separating it from the spinal cord. The alar ligaments start on the lateral aspects of the odontoid process and attach to the base of the skull and the apical ligament, also known as suspensory or middle odontoid, attaches the tip of the odontoid process to the basion. Dorsally, the posterior atlantooccipital membrane is a thin ligament spanning from foramen magnum to atlas. It is continuous with the posterior atlantoaxial membrane, which in turn becomes ligamentum flavum inferiorly (Tubbs et al., 2011). The ligamentous structures of the craniocervical junction are illustrated in Figure 7.4.
The neck
Published in Ashley W. Blom, David Warwick, Michael R. Whitehouse, Apley and Solomon’s System of Orthopaedics and Trauma, 2017
The atlantoaxial unit contributes to the majority of the neck rotation movement and is the most mobile segment of the spine, although it is structurally weak. Simultaneously, it has specific stabilizing structures that prevent excessive motion and disarrangement. The articulation between the atlas and axis comprises one midline atlanto-odontoid joint and two lateral atlantoaxial facet joints. The articular capsules of the lateral facets provide stability and are reinforced by important ligaments, such as the alar ligaments and the transverse atlantal ligament, which is the thickest and the primary stabilizer of the atlas against anterior subluxation. The transverse ligament allows rotation, while the alar ligaments prevent excessive rotation. The apical ligament has an accessory or vestigial role.
Unilateral lag screw fixation of isolated non-union atlas lateral mass fracture: a new technical note
Published in British Journal of Neurosurgery, 2019
Majid Reza Farrokhi, Arash Kiani, Hamid Rezaei
A 46-year-old man was transported by EMS to our emergency department due to multiple trauma following a vehicle turn over accident. He was neurologically intact and despite having upper cervical pain, tenderness and pain on motion, he did not have limitation of motion in cervical spine. Cervical CT-scan revealed unilateral left atlas lateral mass fracture. The gap between the fracture’s edges was approximately 5-mm (Figure 1). Cervical MRI revealed intact transverse and alar ligaments (Figure 2). On lateral flexion and extension radiographs, the fracture was stable showing no displacement. Thus, the patient was treated non-surgically using Minerva orthosis. After about 2 months, he complained of exacerbation of suboccipital pain and limitation of motion, yet he still was neurologically intact. New cervical CT-Scan revealed increased diameter of the fracture’s gap. Further evaluation showed no sign of cervical instability. Despite having a stable fracture type, the patient was scheduled for surgical treatment due to his severe pain and discomfort.
Differential screen and treatment of vestibular dysfunction in an elderly patient: A case report
Published in Physiotherapy Theory and Practice, 2023
Carrie A. Barrett, Donald L Hoover
The patient appeared slightly agitated, and he reported that his general state of irritability was due to his unrelenting symptoms of “dizziness.” He was alert and oriented to person, place, time, and location, however he could only remember 2 of the 3 words in memory recall testing (Chandler et al., 2004; Chase, Lozano, Hanlon, and Bowles, 2018). His Patient-Specific Function Scale (PSFS) was reported as 0, with limitations noted in walking, sit to stand transfers, and bed mobility (Abbott and Schmitt, 2014). He had stable vital measures, denied any cardiopulmonary signs or symptoms, and did not appear in physical distress. Further review of systems included integumentary, which was unremarkable for new skin changes, bilateral lower extremity (LE) edema, and non-healing wounds. Musculoskeletal examination was unremarkable for bilateral upper and lower extremity gross range of motion and strength testing (Fruth, 2017). His cervical spine screening was normal for active range of motion for all directions. Ligamentous instability was negative with Sharp-Purser, Alar ligament testing, and vertebral basilar insufficiency (VBI) testing (Whitney and Herdman, 2007). VBI testing was done by placing the patient in cervical end range extension and 45-degree rotation. Although authors have criticized the VBI testing for having inadequate diagnostic sensitivity and specificity, inconsistency in the literature supports identifying potential ischemia by use of VBI (Araz Server et al., 2018; Richter and Reinking, 2005). Orthostatic hypotension was not assessed due to his ataxia and his reporting intolerance of sit to stand transfers (Bhattacharyya et al., 2017). The patient’s gait was cautious, shuffling, and slow, and he exhibited loss of balance requiring minimum assistance with 3–5 steps within the treatment room.
Integrity of the tectorial membrane is a favorable prognostic factor in atlanto-occipital dislocation
Published in British Journal of Neurosurgery, 2020
Gil Kimchi, Gahl Greenberg, Vincent C. Traynelis, Christopher D. Witiw, Nachshon Knoller, Ran Harel
A 20-year-old male was admitted following a high-velocity motorcycle accident. He suffered multiple injuries including a subdural hematoma that required an ICP monitor insertion, a sternum fracture, a left pneumothorax and multiple lung contusions that necessitated the insertion of a chest tube. On presentation, he was in hemodynamic shock due to a ruptured spleen. His neurological status was GCS 9T and ASIA E. Once stabilized, a CT scan of the cervical spine was performed as part of a multi-trauma extended CT protocol that is practiced in our hospital. Radiographic indicators for AOD included a BDI of 17.4 mm, Powers Ratio of 1.09 and a Condylar-C1 Interval (CCI) of 5.7 mm bilaterally (Figure 1(A,B)). The patient was rigidly immobilized (sand bags immobilization was used in all cases upon diagnosis) and an emergent splenectomy was performed. Immediately following surgery, a cervical MRI demonstrated extensive cervical ligamentous injuries with disruption of the apical and alar ligaments, albeit a preserved tectorial membrane (Figure 1(D)). Medullary edema was also noted (Figure 1(C)). This dislocation was classified as a combined Traynelis Type I and II, based radiographically on an anterior and upward cranial displacement. The patient remained intubated and was admitted to the intensive care unit (ICU). He underwent an occipitocervical fusion three days thereafter. The patient was able to breathe independently through an endotracheal canula, and remained ASIA E throughout his admission. He completed a three months rehabilitation program. He returned to work four months following his injury. His latest follow up visit at our clinic was eight months after the injury; he has no sensory-motor deficits and ambulates independently. He was noted to have a positive bilateral Babinski’s, Tremner’s and Hoffman’s signs but remains asymptomatic.