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PubMed1982

Atlanto-axial malarticulation in Angora goats.

Two male Angora goats presented with ataxia and weakness of the hind limbs. Both tired easily when exercised and often stumbled and fell. In both cases, post-mortem examination revealed focal areas of gliosis and diffuse Wallerian degeneration in the spinal cord at the level of the atlanto-axial joint. There were also two areas of myelomalacia in one of the goats. In the other, the caudal articular surfaces of the atlas were unusually convex and the odontoid process of the axis was laterally compressed. It is suggested that these vertebral anomalies resulted in excessive mobility of the joint leading to the development of a compressive myelopathy.

Animals↗
PubMedDate not supplied

Upper cervical spine injuries.

The unique anatomy of the upper cervical spine and the typical mechanisms of injury yield a predictable variety of injury patterns. Traumatic ligamentous injuries of the atlanto-occipital joint and transverse atlantal ligament are relatively uncommon, have a poor prognosis for healing, and often respond best to surgical stabilization. Bony injuries, including occipital condyle fractures, atlas fractures, most odontoid fractures, and traumatic spondylolisthesis of the axis, generally respond well to nonsurgical management. Controversy in management remains, however, especially with type II odontoid fractures.

Atlanto-Occipital Joint↗
PubMed1998

Anatomic considerations of C2 nerve root ganglion.

STUDY DESIGN: Dissection and observation of the dorsal root ganglion of the second cervical spinal nerve bilaterally. OBJECTIVES: To determine the position of the C2 dorsal root ganglion and the heights of the C2 ganglion and its corresponding foramen. SUMMARY OF BACKGROUND DATA: The dorsal root ganglion has been well studied in the middle and lower cervical spine and in the lumbar spine. In no previous study are the position and height of the C2 dorsal root ganglion and its corresponding foramen described. METHODS: Fifteen cadaveric cervical spines were exposed posteriorly. The C2 nerve roots and ganglia were dissected between the arch of the atlas and the lamina of the axis. The heights of the C2 ganglion and foramen were measured. The location of the C2 ganglion was also macroscopically observed. RESULTS: The heights of the C2 ganglion and foramen are 5.7 +/- 0.8 mm and 7.7 +/- 1.2 mm, respectively. The C2 ganglion occupies 76% of the foramen height. All C2 dorsal root ganglia are confined within foramens between the arch of the atlas and the lamina of the axis. CONCLUSIONS: The C2 dorsal dorsal root ganglia are all proximally placed and occupy most of the foramen height, which may render the C2 ganglion vulnerable to entrapment.

Cadaver↗
PubMed1987

Skull radiograph measurements of normals and patients with basilar impression; use of Landzert's angle.

One hundred normal lateral skull radiographs were studied and those of ten patients with basilar impression attending Kenyatta Hospital, Nairobi. The mean shortest distance of the odontoid tip to McGregor's basal line was 1.2 +/- 2.28 mm below the basal line (range 6 mm below to 3 mm above basal line), in normals and 9 +/- 2.7 mm (6-14 mm) above basal line in patients. The mean basal angle was 113 degrees +/- 7 degrees (102 degrees-133 degrees) in normals and 122 degrees +/- 6 degrees (113 degrees-125 degrees) in patients. The mean nasion-basion-opisthion angle was 162 degrees +/- 4 degrees (154 degrees-169 degrees) in normals and 178 degrees +/- 5 degrees (173 degrees-185 degrees) in patients. The mean total length of clivus was 48 +/- 3.7 mm (43-56 mm) in normals and 44 +/- 6.6 (36-48 mm) in patients group. The mean median diameter of the foramen magnum was 39 +/- 5 mm (30-48 mm), atlas 21 +/- 3 mm (18-25 mm) axis 18 +/- 3 mm (14-23 mm), third cervical vertebra 16 +/- 2 mm (13-22 mm) in normals and in patients: 39 +/- 4 mm (36-45 mm), atlas 23 +/- 6 (15-30 mm) axis 19 +/- 4 mm (16-25 mm), third cervical vertebra 16 +/- 3 (14-20). There was a significant difference in the position of the odontoid tip and the nasion-basion-opisthion angle between the normal and patient groups. All the other parameters measured in this work did not differ significantly between the two groups.

Black People↗
PubMed1980

Stabilization of atlantoaxial subluxation in the dog, using the nuchal ligament.

A technique for the stabilization of atlantoaxial subluxation in the dog was developed. The technique involved use of the nuchal ligament as a means of securing the spinous process of the axis to the dorsal arch of the atlas. Two cases were typical atlantoaxial subluxation in toy-breed dogs, and 2 cases were traumatic subluxation secondary to fracture of the axis in dogs of large breeds. On the basis of the results in these cases, it was concluded that the technique has advantages over techniques in which wire or nonmetallic suture material is utilized for stabilization.

Animals↗
PubMed2002

The third occipital condyle, a constituent part of a median occipito-atlanto-odontoid joint: a case report.

A compound conjunction between basiocciput, atlas (anterior arch), and dens of axis (odontoid process) was found incidentally during routine dissection of the head of an 83-year-old man. According to the patient's history, no neck disability had been recorded. A median saw-cut of the head-and-neck conjunction revealed that the basion was anteriorly reinforced by an osseous pillar 4 mm in length and 3 mm in width. Such a formation is known as a third occipital condyle (condylus tertius, CT). In our case it exhibited one surface oriented in an anterior-inferior direction and articulating with the superior border of the anterior arch of the atlas, and another surface oriented in a posterior-inferior direction and articulating with the superior portion of the dens of axis. The dens of axis itself articulated with the anterior arch of the atlas, forming the (normal) median atlanto-axial joint. Post-mortem computed tomography and post-mortem histological examination completed the investigation. The cartilage of the articular compartment between the CT and the anterior arch of the atlas and the related anterior fibrous disc exhibited severe arthrosis. The findings were discussed in the light of developmental and comparative anatomy.

Aged↗
PubMedDate not supplied

Cervical spine involvement in longstanding ankylosing spondylitis.

OBJECTIVE: To investigate the degree of ossification and the frequency of ankylosis between the atlas and the dens of the axis in patients with longstanding ankylosing spondylitis (AS), to assess radiological involvement of the cervical spine, and to determine their correlations with structural severity and clinical variables, including neurological abnormalities. METHODS: In 61 AS patients with disease duration over 7 years, the findings of conventional radiographs were graded by the Bath Ankylosing Spondylitis Radiology Index (BASRI), and the ossification levels between the atlas and the dens and the severity of zygapophyseal (ZA) joint lesions were scored using multislice CT. Neurological examinations and somatosensory evoked potentials (SSEP) were performed by neurologists. RESULTS: According to the BASRI, 50 patients (82.0%) had radiological changes of the cervical spine > or = score 1. Thirty-seven patients (60.6%) revealed a certain extent of the atlantodental ossification, and the presence of partial or complete atlantodental ankylosis was seen over 30% of the patients. The BASRI-cervical spine score and the atlantodental ossification levels correlated with disease duration. ZA involvement was observed in 49 patients (80.3%), including 23 with ZA fusion (37.7%). Although 4 of 11 patients with atlantoaxial subluxation showed abnormal SSEP none had significant neurological complications. This might be attributed in part to atlantodental ankylosis and ZA fusion. Finally, ossifications of the anterior and posterior longitudinal ligaments were found 26.2 and 29.5%, respectively. CONCLUSION: Cervical spine involvement and atlantodental ossification or ankylosis appear to be common in patients with longstanding AS, and to be particularly more severe in patients with a longer disease duration.

Adult↗
PubMed2000

Contribution of single somites to the skeleton and muscles of the occipital and cervical regions in avian embryos.

Controversy has surrounded the process of resegmentation of cervico-occipital somites. We have reinvestigated this topic by grafting single somites of quail embryos homotopically into chick embryos. Somites one to five contribute to the skull. Somites one and two contribute to the parasphenoid, which develops by direct ossification in a non-segmental fashion. All cartilaginous derivatives of the somites are segmental. Somite two forms a stripe of cells in the basioccipital, exoccipital and supraoccipital. Somites three to five give rise to the subsequent caudal parts of the basioccipital and exoccipital. Somite five forms the first motion segment including the occipital condyle, the cranial part of the atlas and the tip of the dens axis. Therefore, the border between head and neck is in the centre of somite five, and corresponds to the expression boundary of Choxb-3. Somite six forms the caudal part of the atlas and the cranial part of the axis. Somites two to eight all contribute to the cranio-cervical muscles with the exception of the Mm. rectus capitis dorsalis and ventralis and the M. biventer cervicis, which do not receive contributions from somite two. In contrast, the M. cucullaris capitis is exclusively formed by myogenic cells from somite two, which parallels its exclusive innervation by the accessory nerve. Our data confirm the segmental nature of the occiput, and show that resegmentation is a very regular process involving all except the four cranialmost somites. Except for somites one and two, all of the somites contribute to the muscles located at the appropriate levels.

Animals↗
PubMed1999

Marked non-uniformity of fiber-type composition in the primate suboccipital muscle obliquus capitis inferior.

Obliquus capitis inferior (OCI) is a monoarticular suboccipital muscle linking the transverse process of the atlas (C1) to the spinous process of the axis (C2). Histochemical analysis of fiber-type composition showed that the muscle has a marked gradient of fiber-type distribution in which type I fibers comprise 95-100% of fibers in the deepest region but less than 10% of fibers in the superficial layer. Step-like changes in fiber-type proportions occurred between groups of fascicles. In most instances the boundaries between these fascicles did not exhibit different perimysial features from those fascicles with similar fiber-type proportions. OCI contained large numbers of muscle spindles, which were concentrated in deep regions rich in type I fibers. The degree of nonuniformity in fiber-type distribution seen in OCI is unusually large when compared with patterns described in other primate muscles, and has implications for the way that the muscle is studied anatomically and physiologically.

Adenosine Triphosphatases↗