Glossary items beginning with A (26).
Adolescent Scoliosis - lateral spinal curvature that appears before the onset of puberty and before skeletal maturity.
Adult Scoliosis - scoliosis of any cause which is present after skeletal maturity.
Ankylosing Spondylitis - An inflammatory disease of the spine which gradually restricts spinal movement. Primarily occurs in young adults; they commonly have morning pain. Often called "bamboo spine disease".
Anterior - The front portion of the vertebral body. It may also indicate the position of one structure relative to another.
Anterior Longitudinal Ligament - A ligament which attaches to the anterior aspect of every vertebra, from the base of the skull to the sacrum.
Anterior Sacroiliac Ligaments - Ligaments which span the anterior aspect of the sacroiliac joints, spanning from the sacrum to the iliac bones. They are not as strong as the posterior sacroiliac ligaments.
Anterior Spinal Fusion - A surgical technique which involves the removal of the intervertebral disc, and replacement with bone graft. Additional structural supports may be placed in the disc space, such as hard (cortical) bone grafts, metal or synthetic spacers, to maintain good spinal alignment.
Anterior Superior Iliac Spine - The palpable bony prominence at the front of the iliac bone on each side of the pelvis. This is used as a landmark for physical examination.
Anteroposterior View (AP View) - An x-ray in which the patient faces toward the x-ray beam, which passes from anterior to posterior through the patient, and away from the x-ray film.
Apex of Scoliosis - The area of greatest curvature or displacement from the midline of the body.
Apical Vertebra - When referring to a scoliosis, it is the vertebra with the greatest distance from the midline and has the most rotation.
Apophysis - A growth plate which is not apparent on x-rays until the bone is maturing, when it the begins to ossify (change to bone). The iliac apophysis is often used to estimate a child's skeletal maturity.
Arachnoid - A thin layer of connective tissue which is part of the dura which surrounds the brain, and contains the spinal fluid around the spinal cord.
Artery of Adamkiewicz - An artery which primarily supplies blood to the anterior spinal artery to the thoracic and lumbar spinal cord. The level at which it enters the spinal canal varies widely, commonly from T8 to L3. Ischemia from impaired blood flow in this artery may result in spinal cord ischemia.
Ataxic Gait - Uncoordinated, unsteady walking with the feet spread apart (wide-based) which may be caused by either spinal stenosis or a brain (central nervous system) disease.
Atlanto-axial Instability - Abnormal, excessive motion between the first and second cervical vertebrae (C1 & C2). This may be due to disease or injury.
Atlanto-axial Joint - This joint between C1& C2, allows approximately 50% of the cervical spine side-to-side rotation.
Atlanto-axial Rotatory Subluxation - A rotational subluxation of the C1-C2 joints. The patients often appear with the head tilted and cocked to one side and are unable to turn their heads to the other side. Often secondary to injury or retropharyngeal inflammation seen after tonsillectomy. The diagnosis is often delayed, and may require CT scan for a definitive answer.
Atlanto-dens Interval - A measurement on lateral x-rays of the cervical spine of the space between the anterior ring of C1 and the anterior aspect of the dens (odontoid). This space may increase with injury to the supporting ligaments, or damage to the ligaments from disease.
Atlanto-occipital Dislocation - A separation of the upper cervical spine from the skull, secondary to trauma. This is often a fatal injury.
Atlanto-occipital Joint - The joint between the skull and the first cervical vertebra (C1).
Atlas - The first cervical vertebra (C1) to which the skull attaches above and the axis (C2) attaches below.
Autologous Blood - blood collected from a person for later transfusion to that same person. This technique is often used prior to elective surgery if blood loss is expected to occur. This may avoid the use of bank blood from unknown donors.
Autonomic Dysreflexia - This involves over stimulation of the autonomic nervous system in paraplegic patients with spinal cord injury at or above T6, which may manifest itself with excessive sweating, goose flesh, headaches, high blood pressure, slow heart rate, and unusual flushing of the skin. It can be caused by infection, over-distention of the urinary bladder, constipation, or a skin wound. If it remains untreated, it can become a medical emergency or cause death.
Autotransfusion - The practice and technique of transfusing previously drawn autologous blood back to the same patient.
Axis - The second cervical vertebra consisting of a ring of bone and the odontoid as a cephalad projection. As it articulates with the Atlas (C1), it provides 50% of the cervical spine rotation.