General Spinal Anatomy

ACOUSTIC NEURINOMAS - Benign tumor of the hearing nerve (eighth nerve). A progressively enlarging, benign tumor, usually within the internal auditory canal or hearing nerve.

ACROMEGALY - Disorder marked by progressive enlargement of the head, face, hands, feet, and thorax, due to the excessive secretion of growth hormone.

ACTION TREMOR - A type of tremor that occurs during voluntary movements, such as lifting a cup to one's mouth.

ACTIVA TREMOR CONTROL THERAPY - The therapy uses an implanted device to deliver mild electrical stimulation to block the brain signals that cause tremor. The therapy stimulates the target nuclei in the thalamus via an insulated wire lead with electrodes that are surgically implanted in the brain and connected to a pulse generator that is implanted near the collarbone. The stimulation level can be adjusted to get the most possible tremor control with minimal side effects.

ADENOCARCINOMA - Cancer arising from secretory cells, often in a gland. Breast and pancreatic cancers are usually adenocarcinomas.

AGNOSIA - Absence of the ability to recognize the form and nature of persons and things.

AGRAPHIA - Loss of the power of writing due either to muscular incoordination or to an inability to phrase thought.

ALLOGRAFT BONE - Sterile bone derived from another human which is used for grafting procedures.

AMAUROSIS - Loss of vision without discoverable lesion in the eye structures or optic nerve. Amaurosis fugax - temporary blindness occurring in short periods.

AMENORRHEA - Absence of the menses due to causes other than pregnancy or advancing age.

AMNESIA - Loss of memory caused by brain damage or by severe emotional trauma.

ANALGESIA - Loss of sensibility to pain, loss of response to a painful stimulus.

ANAPLASIA - In the case of a body cell, a reversion to a more primitive condition. A term used to denote the alteration in cell character which constitutes malignancy.

ANASTOMOSIS - A communication, direct or indirect: A joining together. In the nervous system a jointing of nerves or blood vessels.

ANESTHESIOLOGIST - Physician who administers pain-killing medications during surgery.

ANENCEPHALY - Absence of the greater part of the brain, often with skull deformity.

ANESTHESIA - Loss of sensation of a body part; or of the body when induced by the administration of a drug.

ANESTHESIOLOGIST - Physician who administers pain-killing medications during surgery.

ANEURYSM - Dilation of an artery, formed by a circumscribed enlargement of its wall. Saccular (berry) aneurysm - sac-like bulging on one side of an artery usually arising at an arterial branching.

ANGIOGRAM - A study which shows the blood vessels leading to and in the brain by injecting a dye or contrast substance through a catheter placed in the artery in the leg.

ANGIOMA - A tumor whose cells tend to form blood vessels (hemangioma) or lymph vessels (lymphangioma).

ANGIOGRAPHY - Radiography of blood vessels using the injection of material opaque to x-rays to give better definition to the vessels.

ANNULUS FIBROSUS - The outer, fibrous, ring-like portion of an intervertebral disc.

ANOREXIA - Loss of appetite; a condition marked by loss of appetite leading to weight loss.

ANTIDIURETIC - An agent which reduces the output of urine. Antidiuretic hormone (ADH) is formed in the hypothalamus and stored in the posterior pituitary gland. Its secretion reduces urine output.

APHASIA - Difficulty with, or loss of use of language, in any of several ways including reading, writing or speaking. Failure of understanding of the written, printed or spoken word not related to intelligence but to specific lesions in the brain.

ARACHNOIDITIS - Inflammation of the arachnoid membrane, most commonly seen within the spinal cord around the spinal cord and cauda equina.

ARNOLD-CHIARI MALFORMATION - A condition in which there is displacement of the medulla and cerebellum into the opening in the basilar part of the occipital bone. It is one of the causes of hydrocephalus and is usually accompanied by spina bifida and menigomyelocele.

ARTERIOSCLEROSIS - Thickening and calcification of the arterial wall with loss of elasticity and contractility.

ARTERIOVENOUS MALFORMATION - Collection of blood vessels with one or several abnormal communications between arteries and veins which may cause hemorrhage or seizures.

ARTHRITIS - Inflammation of a joint usually characterized by swelling, pain and restriction of motion.

ARTHRODESIS - The fusion of bones across a joint space, thereby limiting or eliminating movement. It may occur spontaneously or as a result of a surgical procedure, such as fusion of the spine.

ARTHROSCOPE - An instrument inserted into it's joint cavity to view the interior of a joint and correct certain abnormalities. An arthroscope is an endoscope for use in a joint.

ARTHROSCOPY - The procedure of visualizing the inside of a joint by means of an arthroscope.

ASTROCYTE - Cell which supports the nerve cells (neurons) of the brain and spinal cord.

ASTROCYTOMA - Tumor within the substance of the brain or spinal cord made up of astrocytes - often classified from Grade I (slow-growing) to Grade III (rapid-growing).

ATHETOSIS - A condition in which there is a succession of slow, writhing, involuntary movements of the fingers and hands, and sometimes of the toes and feet.

ATONIC SEIZURE - Seizures that are characterized by a sudden loss of muscle tone, causing the individual to instantly drop to the floor, commonly known as "drop attacks."

AURA - Warning sign that people with epilepsy often experience prior to the onset of a seizure, which may consist of a strange taste, bad feeling, or tingling sensation.

AUTOGENOUS BONE - Bone originating from the same individual; i.e., an individual's own bone.

AUTOGRAFT BONE - Bone transplanted from one part to another part of the body in the same individual.

AUTONOMIC NERVOUS SYSTEM - Involuntary nervous system, also termed the vegetative nervous system. A system of nerve cells whose activities are beyond voluntary control.

AVM (ARTERIOVENOUS MALFORMATION) - Deformity, abnormal shape or structure relating to veins and arteries.

AXON - The part of a nerve cell that usually sends signals to other nerves or structures.

BELL'S PALSY - Paralysis of facial muscles (usually one side) due to facial nerve dysfunction of unknown cause.

BENIGN - Not cancerous; does not invade nearby tissue or spread to other parts of the body.

Bioabsorbable Polymer - A substance, such as some plastics, which the human body can break down and absorb.

Biocompatibility - A characteristic of some materials that when they are inserted into the body do not produce a significant rejection or immune response.

Biodegradation - The breakdown of organic materials into simple chemicals commonly found in the body.

BIOPSY - Removal of a small portion of tissue, usually for the purpose of making a diagnosis.

BLOOD-BRAIN-BARRIER - The barrier which exists between the blood and the cerebrospinal fluid which prevents the passage of various substances from the bloodstream to the brain.

BONE - The hard tissue that provides structural support to the body. It is primarily composed of hydroxyapatite crystals and collagen. Individual bones may be classed as long, short, or flat.

BONE DERIVATIVE - One of the substances extracted from bone, such as bone morphogenic proteins (BMP).

BONE GRAFT- Bone which is harvested from one location in an individual and placed in another individual (allograft bone) or in a different location in the same individual (autogenous bone).

BONE MARROW- The tissue contained within the internal cavities of the bones. A major function of this tissue is to produce red blood cells.

BONE PLATE - Usually a relatively thin metal device which is affixed to bone via screws. Bone plates are used to immobilize bones or bone fragments such that healing can occur.

BONE SCREW - A threaded metal device which is inserted into bone. The functions of bone screws are to immobilize bones or bone fragments or to affix other medical devices, such as metal bone plates, to bones.

BROWN-SEQUARD'S SYNDROME - Loss of sensation of touch, position sense, and movement on the side of a spinal cord lesion, with loss of pain sensation on the other side. Caused by a lesion limited to one side of spinal cord.

BURR - An electrical drilling tool for enlarging atrephine (circular) hole in the cranium.

CADAVER - A term generally applied to a dead human body preserved for anatomical study.

CALLOSUM - The great commisure of the brain between the cerebral hemispheres.

CANCELLOUS BONE - The spongy or honeycomb structure of some bone tissue typically found at the ends of long bones.

CAROTID ARTERY - Large artery on either side of the neck which supplies most of the cerebral hemisphere.

CAROTID SINUS - Slight dilatation on the common carotid artery at its bifurcation containing nerve cells sensitive to blood pressure. Stimulation can cause slowing of the heart, vasodilatation and a fall in blood pressure.

CARPAL TUNNEL - Space under a ligament in wrist through which the median nerve enters the palm of the hand.

Carpal Tunnel Syndrome - A condition caused by compression of the median nerve in the carpal tunnel, characterized especially by discomfort and disturbances of sensation in the hand.

Cartilage - The hard, thin layer of white glossy tissue that covers the end of bone at a joint. This tissue allows motion to take place with a minimum amount of friction.

CT SCAN - (computed tomography scan): A diagnostic imaging technique in which a computer reads x-rays to create a three-dimensional map of soft tissue or bone.

CATHETER - A small tube used to inject a dye to see the blood vessles, similar to that used for looking at vessels in the heart.

CAUDA EQUINA - The bundle of spinal nerve roots arising from the end of the spinal cord and filling the lower part of the spinal canal(from approximately the thoraco-lumbar junction down).

CAUDATE NUCLEUS - Part of the basal ganglia which are brain cells that lie deep in the brain.

Central Nervous System - Part of the nervous system which consists of the brain and spinal cord, to which sensory impulses are transmitted and from which motor impulses pass out, and which supervises and coordinates the activity of the entire nervous system.

CEREBELLUM - The lower part of the brain which is beneath the posterior portion of the cerebrum and regulates unconscious coordination of movement.

CEREBROSPINAL FLUID (CSF) - Water-like fluid produced in the brain that circulates around and protects the brain and spinal cord. Shrinking or expanding of the cranial contents is usually quickly balanced by increase or decrease of this fluid.

Cerebral Cortex - Surface layer of gray matter of the cerebrum that functions chiefly in coordination of higher nervous activity; called also pallium.

Cerebral Palsy - Disability resulting from damage to the brain before or during birth and outwardly manifested by muscular incoordination and speech disturbances.

Cerebrospinal Fluid - Water-like fluid produced in the brain that circulates and protects the brain and spinal cord, known as CSF.

CEREBRUM - The principal portion of the brain, which occupies the major portion of the interior of the skull and controls conscious movement, sensation and thought.

Chemonucleolysis - A treatment of an intervertebral disc that consists of an injection of chymopapain, a drug that dissolves part of the disc.

CHIASM (OPTIC) - Crossing of visual fibers as they head toward the opposite side of the brain. For each optic nerve most of the visual fibers cross to the opposite side, some run directly backward on each side without crossing.

CHOREA - A disorder, usually of childhood, characterized by irregular, spasmodic involuntary movements of the limbs or facial muscles.

CHOROID PLEXUS - A vascular structure in the ventricles of the brain which produces cerebrospinal fluid.

CINGULATE GYRUS � A long, curved convolution of the medial surface of the cortical hemisphere.

CINGULOTOMY - Electronic destruction of the anterior cingulate gyrus and callosum.

Clinical Studies - A process of strictly controlled evaluations involving patients. Some of these studies are required by the FDA prior to general release of a device or compound for use in humans.

Cobalt-Chrome - A term that is used in referring to cobalt-chromium-molybdenum alloy, a mixture of metals used in many surgical implants.

COCCYX - The small bone at the end of the spinal column in man, formed by the fusion of four rudimentary vertebrae. The "tail bone".

Collagen - A fibrous protein which is a major constituent of connective tissue. Such as skin, tendons, ligaments, cartilage, and bones.

Comminuted Fracture - A fracture in which a bone is broken into more than two pieces. Often internal or external fixation devices are used to maintain proper alignment of the fragments.

COMPUTED TOMOGRAPHY (CT) SCAN - A diagnostic imaging technique in which a computer reads x-rays to create a three-dimensional map of soft tissue or bone.

CONCUSSION - A disruption, usually temporary, of neurological function resulting from a blow or violent shaking.

CONTRAST MEDIUM - Any material (usually opaque to x-rays) employed to delineate or define a structure during a radiologic procedure.

CONTUSION - A bruise; an area in which blood that has leaked out of blood vessels is mixed with brain tissue.

CORONAL SUTURE - The line of junction of the frontal bones and the parietal bones of the skull.

CORPUS CALLOSUM - The greatest commissure of the brain between the cerebral hemispheres.

CORTEX - The external layer of gray matter covering the hemispheres of the cerebrum and cerebellum.

CRANIOPHARYNGIOMA - Congenital tumor arising from the embryonic duct between the brain and pharynx.

Craniostenosis - Premature closure of cranial sutures, limiting or distorting the growth of the skull.

CRANIOSYNOSTOSIS - Premature closure of cranial sutures, limiting or distorting the growth of the skull.

CSF SHUNT - A bypass or diversion of accumulations of cerebroospinal fluid to an absorbing or excreting system.

DEEP BRAIN STIMULATION - A tremor control therapy for patients with Parkinson's Disease or essential tremors, who do not respond effectively to medications. It is a surgical reversible procedure that involves implanting a device to deliver mild electrical stimulation to block the brain signals that cause tremor.

De-mineralized Bone - Bone tissue which has been depleted of its minerals; e.g., calcium and phosphorous.

Dendrite - A nerve cell process that transmits impulses toward the cell body.

DEPRESSED SKULL FRACTURE - A break in the bones of the head in which some bone is pushed inward, possibly pushing on or cutting into the brain.

DIABETES INSIPIDUS - Excretion of large amounts of urine of low specific gravity. The inability to concentrate urine.

DIFFUSE AXONAL INJURY - Damage to the axons of many nerve cells that lie in different parts of the brain.

DIFFUSE BRAIN INJURY - Damage to the brain that can affect many parts of the brain, often in a subtle fashion; eaxamples include diffuse axonal injury and inadequate blood flow.

DIPLOPIA - Double vision, due usually to weakness or paralysis of one or more of the extra-ocular muscles.

DISC - The intervertebral disc - cartilaginous cushion found between the vertebrae of the spinal column. It may bulge beyond the vertebral body and compress the nearby nerve root, causing pain. The terms "slipped disc", "ruptured disc" and "herniated disc" are often used interchangeably even though there are subtle differences.

Disc Degeneration - The loss of the structural and functional integrity of the disc.

DOME - The round balloon like portion of the aneurysm which usually arises from the artery from a smaller portion called the neck of the aneurysm.

DOPPLER - A non-invasive study which uses sound waves to show the flow in a blood vessel and can be used to determine the degree of narrowing (percent stenosis) of the vessel. A wand is placed on the skin over the vessel to be imaged. This study has no risks and is not painful.

DURA MATER - A tough fibrous membrane which covers the brain and spinal cord, but is separated from them by a small space.

DYSESTHESIA - A condition in which a disagreeable sensation is produced by ordinary touch, temperature or movement.

DYSPHASIA - Difficulty in the use of language due to a brain lesion without mental impairment.

DYSTONIA MUSCULORM DEFORMANS - An affliction occurring especially in children, marked by muscular contractions producing distortions of the spin and hips.

ELECTROENCEPHALOPGRAHY (EEG) - The study of the electrical currents set up by brain actions; the record made is called an electroencephalogram.

ELECTROMYOGRAPHY (EMG) - A method of recording the electrical currents generated in a muscle during its contraction.

ENDARTERECTOMY - Removal of fatty or cholesterol plaques and calcified deposits from the internal wall of an artery.

ENDOCRINE GLAND - A gland which furnishes an internal secretion, usually having an effect on another organ.

ENDOCRINOPATHY - Any disease due to abnormality of quantity or quality in one or more of the internal gladular secretions.

Endoscope - A medical device for viewing internal portions of the body. It is usually comprised of fiber optic tubes and video display instruments.

Endoscopy - Inspection of internal body structures or cavities using an endoscope.

EPENDYMA - The membrane lining the cerebral ventricles of the brain and central canal of the spinal cord.

EPENDYMOMA - A growth in the brain or spinal cord arising from ependymal tissue.

EPIDURAL HEMATOMA - A blood clot between the dura mater and the inside of the skull.

EPILEPSY - Disorder characterized by abnormal electrical discharges in the brain, causing abnormal sensation, movement or level of consciousness.

Facet - A posterior structure of a vertebra which articulates with a facet of an adjacent vertebra to form a facet joint that allows motion in the spinal column. Each vertebra has two superior and two inferior facets.

FALX (CEREBRI) - An extension of dura between the right and left hemispheres of the brain.

Fatigue Fracture - A fracture that occurs in bone or in other materials. Including metal, as a result of repeated stress as opposed to a single injury.

FONTANELLE - Normal openings in he skull of infants; the largest of these is the anterior fontanel or "soft spot" in the middle of the head.

Food and Drug Administration (FDA) - The Federal government agency that has regulatory authority over the manufacture, distribution, and labeling of drugs, medical devices, and foods.

Fontanelles - "Soft spots" of the infant's head, normal unossified areas in the infant skull.

FORAMINOTOMY - Surgical opening or enlargement of the bony opening traversed by a nerve root as it leaves the spinal canal.

Functional Stereotactic Neurosurgery - Surgery intended to improve the function of the central nervous system. A stereotactic head frame is used along with imaging techniques to map the brain and localize the surgical target.

HEMISPHERECTOMY - Excision of one cerebral hemisphere undertaken for malignant tumors, intractable epilepsy usually associate with infantile hemiplegia due to birth injury and other cerebral conditions.

Herniated Disc - Extrusion of part of the nucleus pulposus material through a defect in the annulus fibrosus.

HERNIATED NUCLEUS PULPOSUS (HNP) - Extrusion of the central portion of an intervertebral disc through the outer cartilaginous ring. The material can compress the spinal cord or nerves in or exiting the spinal canal.

Heterotopic Bone Formation - The occurrence of bone growth in an abnormal location.

Hook - For spinal applications, a metallic medical device used to connect spinal structures to a rod.

HORMONE - A chemical substance formed in one gland or part of the body and carried by the blood to another organ which it stimulates to functional activity.

HYDROCEPHALUS - A condition, often congenital, marked by abnormal and excessive accumulation of cerebrospinal fluid in the cerebral ventricles. This dilates the ventricles and in infants and young children causes the head to enlarge.

HYDROMYELIA - Expansion of the spinal cord due to increased size of the central canal of the cord which is filled with CSF.

Hydroxyapatite (HA) - The lattice-like structure of bone composed of calcium and phosphorous crystals which deposits on collagen to provide the rigid structure of bone.

HYPOPHYSIS CEREBRI - A gland of internal secretion lying on the upper surface of the sphenoid (wedge shaped) bone.

HYPOTHALAMUS - A collection of specialized nerve cells at the base of the brain which controls the anterior and posterior pituitary secretions, and is involved in other basic regulatory functions such as temperature control and attention.

Iliac Bone - A part of the pelvic bone that is above the hip joint and from which autogenous bone grafts are frequently obtained.

Iliac Crest - The large, prominent portion of the pelvic bone at the belt line of the body.

Immobilization - Limitation of motion or fixation of a body part usually to promote healing.

INFUNDIBULUM - A stalk extending from the base of the brain to the pituitary gland.

INTRA-AORTIC BALLOON COUNTER PULSATION DEVICE - a pump which is inserted into the main vessel of the body, the aorta, to help the heart deliver blood to critical organs such as the brain or kidneys.

INTRA-ARTERIAL CATHETERIZATION ANGIOGRAPHY - An invasive study in which a catheter (a small tube) is placed in the artery and contrast material is injected to which makes the blood vessels visible on an X-Ray image. The catheter is inserted in the groin into the femoral artery (the artery to the leg) through a needle, and is guided into the arteries in the neck and head. This study is associated with a very small (less than 0.05 % chance of serious complications) and requires the patient to lie in bed for approximately six hours to allow the leg vessel to heal.

INTRAOPERATIVE CISTERNOGRAPHY - Administration of a contrast dye into the ventricles which are chambers in the brain that contain brain fluid.

In vitro - Describing biological phenomena that are made to occur outside the living body traditionally in a test tube. In vitro is Latin for in glass.

Informed Consent - Consent of the patient who has received sufficient information to have surgery, receive medication, or participate in a clinical study.

Institutional Review Board (IRB) - A committee designated by an institution, such as a hospital, to review and approve research projects; e.g., clinical studies in that institution.

Internal Fixation - The immobilization of bone fragments or joints with implants in order to promote healing or fusion.

Investigational Device Exemption (IDE) - A FDA regulatory status which permits the human use of an unapproved medical device for the purposes of collecting clinical data under strictly controlled conditions.

ISCHEMIA - Inadequate circulation of blood generally due to a blockage of an artery.

Joint - The junction or articulation of two or more bones that permits varying degrees of motion between the bones.

JUGULAR VEINS - The major veins on each side of the neck draining blood from the head towards the heart.

Kyphosis - An abnormal increase in the normal kyphotic curvature of the thoracic spine.

LABYRINTH - The internal ear, comprising the semi-circular canals, vestibule and cochlea.

LAMINA - The flattened or arched part of the vertebral arch, forming the roof of the spinal canal.

Laser - Light Amplification by Stimulated Emission of Radiation. The device that produces a focused beam of light at a defined wavelength that can vaporize tissue. In surgery, lasers can be used to operate on small areas without damaging delicate surrounding tissue.

LEPTOMENINGES - Two thin layers of fine tissue covering the brain and spinal cord (The pia mater and arachnoid).

LEPTOMENINGITIS - Inflammation of the membranes covering the brain and spinal cord.

Ligament - A band of flexible, fibrous connective tissue that is attached at the end of a bone near a joint. The main function of a ligament is to attach bones to one another, to provide stability of a joint, and to prevent or limit some joint motion.

LINEAR ACCELERATOR - Equipment that precisely delivers a concentrated dose of radiation to a predetermined target using x-rays.

Lumbar - The lower part of the spine between the thoracic region and the sacrum. The lumbar spine consists of five vertebrae.

LUMBAR DRAIN - A device (usually a long, thin, flexible tube) inserted through the skin into the cerebrospinal fluid space of the lower back; provides a method of draining cerebrospinal fluid.

MAGNETIC RESONANCE ANGIOGRAPHY (MRA) - A non-invasive study which is conducted in a Magnetic Resonance Imager (MRI). The magnetic images are assembled by a computer to provide an image of the arteries in the head and neck. No contrast material is needed, but some patients may experience claustrophobia in the imager.

MAGNETIC RESONANCE IMAGING (MRI) - Diagnostic test that produces three-dimensional images of body structures using powerful magnets and computer technology rather than x-rays.

MEDIAN NERVE - The nerve formed from the brachial plexus that supplies muscles in the anterior forearm and thumb, as well as, sensation of the hand. It may be compressed or trapped at the wrist in carpal tunnel syndrome.

Medical Device Report (MDR) - The required reporting of' medical device complaints involving a patient death, serious injury, or device malfunction.

MEDULLOBLASTOMA - Tumor composed of medulloblasts which are cells which develop in the roof of the fourth ventricle (medullary velum).

MENINGES - The three membranes covering the spinal cord and brain termed dura mater, arachnoid mater and pia mater.

MENINGIOMA - A firm, often vascular, tumor arising from the coverings of the brain.

MENINGITIS - An infection or inflammation of the membranes covering the brain and spinal cord.

MENINGOCELE - A protrusion of the coverings of the spinal cord or brain through a defect in the skull or vertebral column.

MENINGOENCEPHALITIS - An inflammation or infection of the brain and meninges.

MENINGOENCEPHALOCELE - A protrusion of both the meninges and brain tissue through a skull defect.

MRA - Magnetic Resonance Angiography. A non-invasive study which is conducted in a Magnetic Resonance Imager (MRI). The magnetic images are assembled by a computer to provide an image of the arteries in the head and neck. No contrast material is needed, but some patients may experience claustrophobia in the imager.

MRI - Magnetic Resonance Imaging - Scanning technique for views of the brain or spinal cord. No radiation is involved, but rather pulsed magnetic waves are used to delineate the structures within the brain.

MESENCEPHALIC - Relating to that part of the brain stem known as the mesencephalon.

Minimally Invasive Surgery - Surgery requiring small incision(s), usually performed with endoscopic visualization.

MYELIN - The fat-like substance which surrounds the axon of nerve fibers and forms an insulating material.

MYELOGRAM - An x-ray of the spinal canal following injection of a contrast material into the surrounding cerebrospinal fluid spaces.

MYELOMENINGOCELE - A protrusion of the spinal cord and its coverings through a defect in the vertebral column.

NEOPLASM - Any new or abnormal growth, specifically a new growth of tissue in which the growth is uncontrolled.

Nerve Root - The portion of a spinal nerve in close proximity to its origin from the spinal cord.

NEURALGIA - A paroxysmal pain extending along the course of one or more nerves.

Neurosurgery - The surgical specialty involved in the treatment of disorders of the brain, spinal cord, and peripheral nerves.

Neural Arch - The bony arch of the posterior aspect of a vertebra that surrounds the spinal cord, also referred to as the vertebral arch.

NEURITIS - Inflammation of a nerve; may also be used to denote non-inflammatory nerve lesions of the peripheral nervous system.

NEUROBLASTOMA - Tumor of sympathetic nervous system origin, found mostly in infants and children.

NEUROFIBROMA - A tumor of the peripheral nerves due to an abnormal collection of fibrous and insulating cells.

NEUROFIBROMATOSIS - A familial condition characterized b y developmental changes in the nervous system, muscles and skin, marked by numerous tumors affecting these organ system.

NEUROMA - A tumor or new growth largely made up of nerve fibers and connective tissue.

NEUROPATHY - Any functional or pathologic disturbance in the peripheral nervous system.

NEUROSTIMULATOR - A device for electrical excitation of the central or peripheral nervous system.

Non-Union - Failure of the fragments of a fractured bone to heal or to obtain bony fusion following an arthrodesis.

Nucleus Pulposus - The semi-gelatinous tissue in the center of an intervertebral disc. It is surrounded and contained by the annulus fibrosus which prevents this material from protruding outside the disc space.

NYSTAGMUS - Involuntary rapid movement of the eyes in the horizontal, vertical or rotary planes of the eyeball.

OLIGODENDROGLIA - Non-nerve cells, (see glia) forming part of the supporting structure of the central nervous system.

Orthopaedics (also Orthopedics) - The medical specialty involved in the preservation and restoration of function of the musculoskeletal system that includes treatment of spinal disorders and peripheral nerve lesions.

Orthopaedic Implants - Medical devices used to replace or provide fixation of bone or to replace articulating surfaces of a joint.

OSTEOMYELITIS - Inflammation of bone due to infection, which may be localized or generalized.

Osteoporosis - A disorder in which bone is abnormally brittle, less dense, and is the result of a number of different diseases and abnormalities.

PAPILLEDEMA - Swelling of the optic nerve head, can be seen in the back of the retina during eye examination.

Pedicle -The part of each side of the neural arch of a vertebra. It connects the lamina with the vertebral body.

Periosteum - A fibrous membrane that covers the surface of bone except at the end of the bones where it is covered with cartilage as part of a joint. In children, periosteum is involved in forming new bone and molding the configuration of bone; and in the adult, the periosteum forms new bone secondary to injury or infection.

Physical Therapy - The treatment consisting of exercising specific parts of the body such as the legs, arms, hands or neck, in an effort to strengthen, regain range of motion, relearn movement and/or rehabilitate the musculoskeletal system to improve function.

Physiology -The science of the functioning of living organisms, and of their component systems or parts.

PITUITARY- Gland at base of the brain which secretes hormones into the blood stream. Those hormones then regulate other glands including the thyroid, adrenals and gonads. The "Master Gland".

PORENCEPHALY - Abnormal cavity within brain tissue, usually resulting from outpouching of a lateral ventricle.

POST-ICTAL - State following a seizure, often characterized by altered function of the limbs and/or mentation.

Powered Surgical Instruments - Instruments which are powered by compressed air or electricity and are used in surgical procedures to cut, drill, or otherwise remove bone and cartilage, as well as to evacuate fluids.

Pre-Clinical Studies - Tests occurring prior to clinical studies, usually in vitro or in vivo involving animals. The purpose of these studies is to determine the safety and efficacy of the test material.

Premarket Notification [510(k)] - A regulatory method for gaining clearance from the FDA to market a device. The FDA is petitioned by a company to determine if a particular medical device is "substantially equivalent" to a device which was commercially available prior to May 28, 1976. This method usually applies to Class I or II medical devices.

Premarket Approval (PMA) - A regulatory method for gaining a marketing clearance from the FDA for a Class III medical device. A company submits information to the FDA that documents the safety and effectiveness of the device.

PROPRIOCEPTION - Sensation concerning movements of joints and position of the body in space.

Prosthesis - An artificial body part such as an artificial leg or arm. The term prosthesis is also used to describe some of the implants used in the body such as a hip or knee replacement device.

PSEUDOTUMOR CEREBRI - Raised intracranial pressure, usually causing only headache and papilledema. No clear underlying structural abnormality.

Pseudoarthrosis (also Pseudarthrosis) - A form of non-union in which there is the formation of a false joint with some cartilage covering the ends of the bones and a cavity containing fluid that resembles a normal joint.

PUPIL - The black part of the eye through which light enters; enlarges in dim light and decreases in size in bright light.

RADIATION ONCOLOGIST - A medical doctor who has received advanced training in the treatment of persons receiving x-ray treatment for an illness.

RADIATION PHYSICIST - A person having a PhD degree who is trained in the science dealing with the properties, changes and interactions of continous energy.

RADIOLOGIST - A medical doctor who has received specialized training in interpreting x-rays, CTs, MRIs and performing angiography.

Resorption - The removal of bone tissue by normal physiological process or as part of a pathological process such as an infection.

Rod - In spinal applications, a slender, metal implant which is used to immobilize and alien the spine.

SACCULAR ANEURYSM - A balloon-like outpouching of a vessel (the more common type of aneurysm).

SCOTOMA - An area of decreased vision surrounded by an area of less depressed or normal vision.

Sacrum - A part of the spine that is also part of the pelvis. It articulates with the ilia at the sacroiliac joints and articulates with the lumbar spine at the lumbosacral joint. The sacrum consists of five fused vertebrae that have no intervertebral discs.

Sciatica - A lay term indicating pain alone the course of a sciatic nerve, especially noted in the back of the thigh and below the knee.

Sepsis - A state of infection of tissue due to disease-producing bacteria or toxins.

SHUNT - A tube or device implanted in the body (usually made of Silastic) to redivert excess CSF away from the brain to another place in the body.

Skeleton - The rigid framework of bones that gives form to the body, protects and supports the soft organs and tissues, and provides attachments for muscles.

SPINA BIFIDA - A congenital defect of the spine marked by the absence of a portion of the spine.

Spinal Canal - The bony channel that is formed by the intravertebral foramen of the vertebrae and in which contains the spinal cord and nerve roots.

Spinal Cord - The longitudinal cord of nerve tissue that is enclosed in the spinal canal. It serves not only as a pathway for nervous impulses to and from the brain, but as a center for carrying out and coordinating many reflex actions independently of the brain.

SPINAL FUSION - Operative method of strengthening and limiting motion of the spinal column. Can be performed with a variety of metal instruments and bone grafts, or bone grafts alone.

Spinal Stenosis - Reduction in the diameter of the spinal canal due to new bone formation which may result in pressure on the spinal cord or nerve roots.

Spine - The flexible bone column extending from the base of the skull to the tailbone. It is made up of 33 bones, known as vertebrae. The first 24 vertebrae are separated by discs known as intervertebral discs, and bound together by ligaments and muscles. Five vertebrae are fused together to form the sacrum and 4 vertebrae are fused together to form the coccyx. The spine is also referred to as the vertebral column, spinal column, or backbone.

Spinous Process - The portion of the vertebrae that protrudes posteriorly from the spinal column. The spinous processes create the "bumps" felt on the midline of the back.

Spondylolisthesis - A defect in the construct of bone between the superior and inferior facets with varying degrees of displacement so the vertebra with the defect and the spine above that vertebra are displaced forward in relationship to the vertebrae below. It Is usually due to a developmental defect or the result of a fracture.

Spondylolysis - Displacement of one vertebrae over another with fracture of a posterior portion of the vertebra. A defect in the neural arch between the superior and inferior facets of vertebrae without separation at the defect and therefore no displacement of the vertebrae. It may be unilateral or bilateral and is usually due to a developmental defect but may be secondary to a fracture.

Stainless Steel - Iron-based metal containing chromium that is highly resistant to stain, rust, and corrosion. Certain grades of stainless steel are commonly used to make surgical implants and instruments.

STEREOTACTIC - Originated from the Greek words stereo meaning three dimensional and tactos meaning touched and relating to stereotaxy.

STEREOTAXY - A precise method of destroying deep-seated brain structures located by use of three dimension coordinates.

STEREOTACTIC RADIOSURGERY - The precise delivery of radiation to a preselected stereotactically localized target.

Sterilization - The method used to render a material free from living organisms. Usual methods include steam under pressure, gas, and ionizing radiation.

STRABISMUS - Deviation of eye movement which prevents the two eyes from moving in a parallel fashion.

SUBARACHNOID HEMORRHAGE - Blood in, or bleeding into, the space under the arachnoid membrane, most commonly from trauma or from rupture of an aneurysm.

SUBDURAL HEMATOMA - a collection of blood (clot) trapped under the dura matter, the outermost membrane surrounding the brain and spinal cord.

Superior - Situated above or directed upward toward the head of an individual.

Tendon - The fibrous band of tissue that connects muscle to bone. It is mainly composed of collagen.

TENTORIUM CEREBELLI - The process of the dura matter between the cerebrum and cerebellum supporting the occipital lobes.

TERATOMA - Tumor or growth made up of several different types of tissue (fat, bone, muscle, skin).

Third Party Payor - The source of reimbursement or payment of charges for medical services when the patient does not make direct payment: i.e. payments made by insurance companies, government agencies or employers. The patient and the doctor represent the two other parties in third party pay arrangements.

Thoracic - The chest level region of the spine that is located between the cervical and lumbar vertebrae. It consists of 12 vertebrae which serve as attachment points for ribs.

Toxicology - The study of the toxic or harmful effects of substances on the body.

TRACTOTOMY - Surgical section of a fiber tract of the central nervous system.

Transplant - The implantation of bone tissue, as in grafting, from one part of the body to another. Transplant also refers to the transfer of an organ such as a kidney or heart from one individual to another.

TRANSSPHENOIDAL APPROACH - Operative method of reaching the pituitary gland or skull base traversing the nose and sinuses.

TRIGEMINAL NEURALGIA - Paroxysmal pain in the face. Pain may be so severe that it causes an involuntary grimace or "tic". (Tic Douloureux).

ULTRASOUND - The use of high-frequency sound to create images of internal body structures.

U.S. Food and Drug Administration (FDA) - Government agency that regulates all medical devices and drugs.

Back to Glossary

Vagus Nerve - The tenth cranial nerve, which is a mixed nerve that has both motor and sensory function.

Vagus Nerve Stimulation (VNS) - Therapy for epilepsy which applies small electrical pulses to the vagus nerve in the neck which regulates internal organs. This therapy is used in patients suffering from partial epilepsy who have failed traditional drug therapy.

VALVE - Device placed in a shunt system to regulate the rate and direction of CSF flow.

VASOPRESSIN - A hormone secreted by the hypothalamus and stored in the posterior pituitary which raises blood pressure and increases reabsorption of water by the kidneys.

VASOPRESSOR - An agent which constricts the arteries and raises blood pressure.

VENTRICLE - The cavities or chambers within the brain which contain the cerebrospinal fluid. There are two lateral ventricles and midline third and fourth ventricles.

VENTRICULOSTOMY - An opening into the ventricles of the brain, such as by inserting a small, thin, hollow catheter.

VENTRICULAR DRAINAGE - Insertion of a small tube into the ventricles to drain cerebrospinal fluid, usually when pressure is increased.

Ventriculostomy - The surgical opening in a ventricle of the brain to drain cerebrospinal fluid, especially in hydrocephalus.

VERTEBRA - One of the 33 bones of the spinal column. A cervical, thoracic, or lumbar vertebra has a cylindrically-shaped bony anteriorly and a neural arch posteriorly (composed primarily of the laminae and pedicles as well as the other structures in the posterior aspect of the vertebra) that protects the spinal cord. The plural of vertebra is vertebrae.

VERTIGO - An abnormal sensation of rotation or movement of one's self, or the environment.

Wire - Metal thread available in various diameters and various degrees of stiffness and is generally used in surgery to transfix fractured bone.

Viscogliosi, A. A. An Investor's guide to Orthopedic Terms. In M.R. Viscogliosi (Ed.), New York, NY: Martin Simpson & Company, Inc., 1992.

Code of Federal Regulations, Food and drug, 21, Parts 800-1299. Washington: Office of the Federal Register, National Archives and Records Administration, 1990.

Glossary of Spinal Terminology. Park Ridge, IL: American Academy of Orthopaedic Surgeons, 1985.

Dorland's Illustrated Medical Dictionary. Philadelphia, PA: W.B. Saunders Company, 1965.

Webster's Medical Desk Dictionary. Springfield, MA: Merriam Webster, Inc., 1986.