Ligamentum Flavum: The paired bands of yellow elastic tissue that connect adjoining laminae of the vertebrae. With the laminae, it forms the posterior wall of the spinal canal and helps hold the body erect.Ossification, Heterotopic: The development of bony substance in normally soft structures.Laminectomy: A surgical procedure that entails removing all (laminectomy) or part (laminotomy) of selected vertebral lamina to relieve pressure on the SPINAL CORD and/or SPINAL NERVE ROOTS. Vertebral lamina is the thin flattened posterior wall of vertebral arch that forms the vertebral foramen through which pass the spinal cord and nerve roots.Ossification of Posterior Longitudinal Ligament: A calcification of the posterior longitudinal ligament of the spinal column, usually at the level of the cervical spine. It is often associated with anterior ankylosing hyperostosis.Ligaments: Shiny, flexible bands of fibrous tissue connecting together articular extremities of bones. They are pliant, tough, and inextensile.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.Longitudinal Ligaments: Two extensive fibrous bands running the length of the vertebral column. The anterior longitudinal ligament (ligamentum longitudinale anterius; lacertus medius) interconnects the anterior surfaces of the vertebral bodies; the posterior longitudinal ligament (ligamentum longitudinale posterius) interconnects the posterior surfaces. The commonest clinical consideration is OSSIFICATION OF POSTERIOR LONGITUDINAL LIGAMENT. (From Stedman, 25th ed)Spinal Stenosis: Narrowing of the spinal canal.Thoracic Vertebrae: A group of twelve VERTEBRAE connected to the ribs that support the upper trunk region.Epidural Space: Space between the dura mater and the walls of the vertebral canal.Radiculopathy: Disease involving a spinal nerve root (see SPINAL NERVE ROOTS) which may result from compression related to INTERVERTEBRAL DISK DISPLACEMENT; SPINAL CORD INJURIES; SPINAL DISEASES; and other conditions. Clinical manifestations include radicular pain, weakness, and sensory loss referable to structures innervated by the involved nerve root.Spinal DiseasesCervical Vertebrae: The first seven VERTEBRAE of the SPINAL COLUMN, which correspond to the VERTEBRAE of the NECK.Brevibacterium: A gram-positive organism found in dairy products, fresh and salt water, marine organisms, insects, and decaying organic matter.Lumbar Vertebrae: VERTEBRAE in the region of the lower BACK below the THORACIC VERTEBRAE and above the SACRAL VERTEBRAE.Hematoma: A collection of blood outside the BLOOD VESSELS. Hematoma can be localized in an organ, space, or tissue.Brevibacterium flavum: A species in the genus CORYNEBACTERIUM, family Corynebacteriaceae, which is used for industrial production of the amino acid LYSINE. It is closely related to Corynebacterium glutamicum.Decompression, Surgical: A surgical operation for the relief of pressure in a body compartment or on a body part. (From Dorland, 28th ed)Elastic Tissue: Connective tissue comprised chiefly of elastic fibers. Elastic fibers have two components: ELASTIN and MICROFIBRILS.Spinal Canal: The cavity within the SPINAL COLUMN through which the SPINAL CORD passes.Intervertebral Disc: Any of the 23 plates of fibrocartilage found between the bodies of adjacent VERTEBRAE.Lumbosacral Region: Region of the back including the LUMBAR VERTEBRAE, SACRUM, and nearby structures.Cysts: Any fluid-filled closed cavity or sac that is lined by an EPITHELIUM. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues.Myelography: X-ray visualization of the spinal cord following injection of contrast medium into the spinal arachnoid space.Spinal Cord Diseases: Pathologic conditions which feature SPINAL CORD damage or dysfunction, including disorders involving the meninges and perimeningeal spaces surrounding the spinal cord. Traumatic injuries, vascular diseases, infections, and inflammatory/autoimmune processes may affect the spinal cord.Thalictrum: A plant genus of the family RANUNCULACEAE. Members contain isoquinoline alkaloids and triterpene glycosides.Anesthesia, Epidural: Procedure in which an anesthetic is injected into the epidural space.