Functional anatomy of the upper cervical spine
1, atlas atlas without vertebral body, supporting the skull.
Atlas: ancient Greek mythology of the giant god. After the failure of the rebellion, was punished by Zeus to support the heavenly sphere.
Ancient Greek writer Pollux (134 ~ 192) named the first cervical vertebra Atlas.
2, pivotal Axis derived from the ancient Greek word axon, the ancient Greek writer Pollux (134 ~ 192) named the pivotal vertebrae for this, also known as the throat Buddha in Asia, used in the past to cover the upper end of the urn.
3, functional anatomy of the atlantoaxial spine intervertebral joint of the circumferential vertebral surface for the plane, the cardinal vertebral surface for the upward convex arc, the overall outward and forward tilt, but can be multi-directional activities.
The atlantoaxial joint has 30~40 degrees of rotation, accounting for about 30% of the total rotation of the cervical spine, and the rotation is accompanied by semi-dislocation-like sliding of the intervertebral joint.
The anterior and posterior flexion and extension movements of the atlantoaxial joint can be 30 to 60 degrees, accounting for about 25% to 45% of all cervical spine movements.
Lateral flexion motion is rare and is usually accompanied by about 1 mm of lateral sliding.
Movement of the atlanto-occipital joint is rare, acting mainly as a mild nodding motion with approximately 4 degrees of rotational motion. Movement of the cervical spine decreases with increasing age.
Definition of upper cervical instability The atlanto-occipital and atlanto-axial joints are congenitally dysplastic, or their structural function is reduced by acquired trauma and various other causes to the point of hypermobility, abnormal movement, or inability to maintain normal position under physiological load, with a range of clinical manifestations such as local pain and nerve compression.
The stability of the upper cervical spine is provided by the occipital condyle. The structural stability of the atlantoaxial, pivotal, and pivotal vertebrae, as well as the ligaments, muscles, joint capsule, and fascia, are jointly maintained.
Causes of instability of the upper cervical spine include trauma. Inflammation, congenital deformity, rheumatoid arthritis, tuberculosis, tumor and medically induced injury.
1, trauma trauma-induced atlanto-occipital dislocation, mostly involving the medulla oblongata. Often die before resuscitation. Atlanto-occipital joint instability is clinically more common.
(1) Atlantoaxial arch fracture (Jefferson fracture). It may be combined with a fracture of the dentate process and or a rupture of the atlantoaxial transverse ligament.
(2) Atlantoaxial dislocation and subluxation.
(3) Dentate fracture
(4) Hangman fracture
2. The embryogenesis and development of the occipital and upper cervical vertebrae of congenital malformations are significantly different from those of other vertebral segments.
(1) Dentate: there is dysplasia. The absence or free state is usually called dentate free tuberosity deformity.
(2) Atlanto-occipital fusion: It is mainly due to incomplete segmentation of the occipital bones and the first cervical vertebrae during embryonic development. When the anterior and posterior arches of the atlantoaxial spine are completely fused with the edge of the foramen magnum, it is a complete occipito-cervical fusion; fusion at the anterior arch but not at the posterior arch or partial fusion; or fusion on one side but not on the other side is called partial occipito-cervical fusion. It may lead to increased mobility of the atlantoaxial joint and instability of the upper cervical spine.
(3) Klippel-Feil short neck deformity.
(4) Congenital malformation of the atlantoaxial joint can lead to atlantoaxial joint rotational dislocation due to chromosomal abnormalities.
(3) Pharyngeal inflammation is a cause of instability of the upper cervical spine. Inflammation of the pharynx invades the pharyngeal wall leading to inflammatory changes in the ligaments and joint capsule, followed by laxity, or congestive decalcification makes the ligament attachment loose leading to rotational dislocation and fixation of the atlantoaxial joint.
4, rheumatoid arthritis autoimmune inflammation mostly involves the atlantoaxial synovial tissue, resulting in atlantoaxial subluxation. Subluxation can be divided into horizontal subluxation and vertical subluxation. Horizontal subluxation is divided into anterior subluxation, posterior subluxation, and lateral subluxation. Vertical subluxation is caused by the narrowing of the joint space when the atlantoaxial joint is involved and the relative lengthening of the tip of the dentate process due to the value-added granulation tissue. When the vertical subluxation is combined with atlantoaxial joint dislocation, it can cause serious consequences.
5.Medical factors Some patients have different degrees of cervical instability before surgery, once this is neglected, the upper cervical instability may not be treated or even aggravated due to improper treatment.
6, tuberculosis, tumor tuberculosis, tumor damage atlanto-occipital, atlanto-axial joint stability to cause instability of the upper cervical spine. Benign tumors are less common among primary tumors.
Fourth, the diagnosis of upper cervical instability needs to rely on medical history, clinical manifestations, physical examination, X-rays and other examinations. Upper cervical instability is often non-specific in clinical manifestations, and it is difficult to find abnormal activities between atlantoaxial vertebrae by simple physical examination, so it is necessary to rely on X-ray and CT examination to determine the diagnosis.
1.Clinical features
(1) Unexplained cranial symptoms, such as occipital and cervical pain limb weakness numbness vertigo nausea, tinnitus, diplopia, dyspnea, sudden collapse, etc.
(2) Head and face deformity or asymmetry, low hairline or short neck deformity, etc.
(3) The appearance of neurological symptoms of occipital foramen magnum area syndrome, etc.
(2) Physical examination of oblique neck, neck and shoulder pain and restricted rotational movement. Of course, patients may develop neurological symptoms, such as extremity cone bundle symptoms and increased muscle tone. Hyperreflexia. Sensory disturbances or hypersensitivity in the extremities. Occipital and cervical pressure pain, electric shock-like sensation may be present, and Hoffman’s sign is mostly positive. Babinski’s pathological reflex may be present.
3. Radiological features usually require forceps open-mouth orthopantomogram, lateral view. Open-mouth oblique film, power forceps, tomographic radiographs.
Open orthogonal position: clear open mouth position film if the centrifugal separation of the two sides of the block is greater than 6.9 mm, the lateral fast loss of ligament control, resulting in instability in the region, severe manifestation of atlantoaxial subluxation. In the case of rotational subluxation fixation, the opening position film mainly shows that the relationship between the dentate process and the lateral fast of the atlantoaxial vertebrae is abnormal, the atlantosteal spacing is unequal, and the chin and the spinous process of the pivot are on the same side of the midline.