Sacrum: Five fused VERTEBRAE forming a triangle-shaped structure at the back of the PELVIS. It articulates superiorly with the LUMBAR VERTEBRAE, inferiorly with the COCCYX, and anteriorly with the ILIUM of the PELVIS. The sacrum strengthens and stabilizes the PELVIS.Chordoma: A malignant tumor arising from the embryonic remains of the notochord. It is also called chordocarcinoma, chordoepithelioma, and notochordoma. (Dorland, 27th ed)Boswellia: A plant genus of the family BURSERACEAE used medicinally since ancient times. It is a source of salai guggal (the gum resin), boswellic acid (ursane type TRITERPENES), and FRANKINCENSE.Spinal NeoplasmsSacroiliac Joint: The immovable joint formed by the lateral surfaces of the SACRUM and ILIUM.Giant Cell Tumor of Bone: A bone tumor composed of cellular spindle-cell stroma containing scattered multinucleated giant cells resembling osteoclasts. The tumors range from benign to frankly malignant lesions. The tumor occurs most frequently in an end of a long tubular bone in young adults. (From Dorland, 27th ed; Stedman, 25th ed)Pelvis: The space or compartment surrounded by the pelvic girdle (bony pelvis). It is subdivided into the greater pelvis and LESSER PELVIS. The pelvic girdle is formed by the PELVIC BONES and SACRUM.Lordosis: The anterior concavity in the curvature of the lumbar and cervical spine as viewed from the side. The term usually refers to abnormally increased curvature (hollow back, saddle back, swayback). It does not include lordosis as normal mating posture in certain animals ( = POSTURE + SEX BEHAVIOR, ANIMAL).Pelvic Bones: Bones that constitute each half of the pelvic girdle in VERTEBRATES, formed by fusion of the ILIUM; ISCHIUM; and PUBIC BONE.Resins, Plant: Flammable, amorphous, vegetable products of secretion or disintegration, usually formed in special cavities of plants. They are generally insoluble in water and soluble in alcohol, carbon tetrachloride, ether, or volatile oils. They are fusible and have a conchoidal fracture. They are the oxidation or polymerization products of the terpenes, and are mixtures of aromatic acids and esters. Most are soft and sticky, but harden after exposure to cold. (From Grant & Hackh's Chemical Dictionary, 5th ed & Dorland, 28th ed)Ilium: The largest of three bones that make up each half of the pelvic girdle.Coccyx: The last bone in the VERTEBRAL COLUMN in tailless primates considered to be a vestigial tail-bone consisting of three to five fused VERTEBRAE.Lumbar Vertebrae: VERTEBRAE in the region of the lower BACK below the THORACIC VERTEBRAE and above the SACRAL VERTEBRAE.Infusions, Intraosseous: The administration of medication or fluid through a needle directly into the bone marrow. The technique is especially useful in the management of pediatric emergencies when intravenous access to the systemic circulation is difficult.Lumbosacral Region: Region of the back including the LUMBAR VERTEBRAE, SACRUM, and nearby structures.Lumbosacral Plexus: The lumbar and sacral plexuses taken together. The fibers of the lumbosacral plexus originate in the lumbar and upper sacral spinal cord (L1 to S3) and innervate the lower extremities.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)Fractures, Stress: Fractures due to the strain caused by repetitive exercise. They are thought to arise from a combination of MUSCLE FATIGUE and bone failure, and occur in situations where BONE REMODELING predominates over repair. The most common sites of stress fractures are the METATARSUS; FIBULA; TIBIA; and FEMORAL NECK.Ischium: One of three bones that make up the coxal bone of the pelvic girdle. In tetrapods, it is the part of the pelvis that projects backward on the ventral side, and in primates, it bears the weight of the sitting animal.Polyradiculopathy: Disease or injury involving multiple SPINAL NERVE ROOTS. Polyradiculitis refers to inflammation of multiple spinal nerve roots.Sacrococcygeal Region: The body region between (and flanking) the SACRUM and COCCYX.Oils, Volatile: Oils which evaporate readily. The volatile oils occur in aromatic plants, to which they give odor and other characteristics. Most volatile oils consist of a mixture of two or more TERPENES or of a mixture of an eleoptene (the more volatile constituent of a volatile oil) with a stearopten (the more solid constituent). The synonym essential oils refers to the essence of a plant, as its perfume or scent, and not to its indispensability.Scoliosis: An appreciable lateral deviation in the normally straight vertical line of the spine. (Dorland, 27th ed)Spinal Fractures: Broken bones in the vertebral column.Spine: The spinal or vertebral column.Cauda Equina: The lower part of the SPINAL CORD consisting of the lumbar, sacral, and coccygeal nerve roots.Bone Screws: Specialized devices used in ORTHOPEDIC SURGERY to repair bone fractures.Bone Neoplasms: Tumors or cancer located in bone tissue or specific BONES.