Atlanto-Axial Joint: The joint involving the CERVICAL ATLAS and axis bones.AxisCervical Atlas: The first cervical vertebra.DislocationsAtlanto-Occipital Joint: The point of articulation between the OCCIPITAL BONE and the CERVICAL ATLAS.Odontoid Process: The toothlike process on the upper surface of the axis, which articulates with the CERVICAL ATLAS above.Occipital Bone: Part of the back and base of the CRANIUM that encloses the FORAMEN MAGNUM.Joint Instability: Lack of stability of a joint or joint prosthesis. Factors involved are intra-articular disease and integrity of extra-articular structures such as joint capsule, ligaments, and muscles.Torticollis: A symptom, not a disease, of a twisted neck. In most instances, the head is tipped toward one side and the chin rotated toward the other. The involuntary muscle contractions in the neck region of patients with torticollis can be due to congenital defects, trauma, inflammation, tumors, and neurological or other factors.Cervical Vertebrae: The first seven VERTEBRAE of the SPINAL COLUMN, which correspond to the VERTEBRAE of the NECK.Joints: Also known as articulations, these are points of connection between the ends of certain separate bones, or where the borders of other bones are juxtaposed.Traction: The pull on a limb or a part thereof. Skin traction (indirect traction) is applied by using a bandage to pull on the skin and fascia where light traction is required. Skeletal traction (direct traction), however, uses pins or wires inserted through bone and is attached to weights, pulleys, and ropes. (From Blauvelt & Nelson, A Manual of Orthopaedic Terminology, 5th ed)Spinal Fusion: Operative immobilization or ankylosis of two or more vertebrae by fusion of the vertebral bodies with a short bone graft or often with diskectomy or laminectomy. (From Blauvelt & Nelson, A Manual of Orthopaedic Terminology, 5th ed, p236; Dorland, 28th ed)Tuberculosis, Osteoarticular: Tuberculosis of the bones or joints.Spondylitis: Inflammation of the SPINE. This includes both arthritic and non-arthritic conditions.Ankylosis: Fixation and immobility of a joint.Spinal Cord Compression: Acute and chronic conditions characterized by external mechanical compression of the SPINAL CORD due to extramedullary neoplasm; EPIDURAL ABSCESS; SPINAL FRACTURES; bony deformities of the vertebral bodies; and other conditions. Clinical manifestations vary with the anatomic site of the lesion and may include localized pain, weakness, sensory loss, incontinence, and impotence.Ligaments, Articular: Fibrous cords of CONNECTIVE TISSUE that attach bones to each other and hold together the many types of joints in the body. Articular ligaments are strong, elastic, and allow movement in only specific directions, depending on the individual joint.Range of Motion, Articular: The distance and direction to which a bone joint can be extended. Range of motion is a function of the condition of the joints, muscles, and connective tissues involved. Joint flexibility can be improved through appropriate MUSCLE STRETCHING EXERCISES.Knee Joint: A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.Decompression, Surgical: A surgical operation for the relief of pressure in a body compartment or on a body part. (From Dorland, 28th ed)