Medical Terminology

To assist you in better understanding the medical field, and specifically neurology, we have provided a list of common terms below. Click on any section to view the terminology in that section if it is not already open.


Alpha receptors: Found primarily in the smooth muscle tissue of peripheral blood vessels and in the sphincters of the gastrointestinal and genitourinary tracts. Stimulation of the alpha receptors causes contraction of these smooth muscles, which may result in an increase in blood pressure due to constriction of peripheral blood vessels.

Amnesia: Partial or total memory loss usually due to brain injury, illness, or psychological disturbances.

Amyotrophic lateral sclerosis: Also known as ALS (Lou Gehrig’s disease). It is a degenerative disease of the motor neurons.

Aneurysms: An abnormal increase in diameter (dilation) of a blood vessel. The rupture of intracranial aneurysms resulting in bleeding into space around the brain, can lead to severe disability or death.

Angiogram: Radiologic study that provides pictures of blood vessels of the brain and spinal cord using injected dye and x-rays.

Anterior: The front of the body.

Aphasia: A condition that is due to brain damage. It’s the loss of the ability to speak, write, or comprehend the written or spoken word.

Apraxia: An impairment in the ability to perform purposeful acts or to properly use familiar objects.

Arthritis: Inflammation of a joint usually characterized by swelling, pain, and restriction of motion.

Astrocytoma: Brain/spinal cord tumor that arises from astrocyte cells (one type of glial cell [a glue-like structure or tissue] ).

Athetosis: A condition of constant involuntary movements (usually of the upper extremities) that are slow, irregular and snake-like.

VM: Arterial Venous Malformation — a tangle of abnormal blood vessels in the brain that may bleed or cause seizures or both. It can be treated by surgical removal, radiation, or “clotting off of the vessels (embolization) or a combination of these.

Axon: Extends away from the cell body and conducts impulses away from the nerve cell. Some axons, but not all, are protected by a white fatty tissue covering called myelin.

Bell’s palsy: Paralysis of the facial (seventh cranial) nerve that causes a unilateral distortion of the affected side of the face.

Beta receptors: Located primarily in the muscles of the heart and in fatty tissue. Stimulation of these receptors in the heart produces a more rapid heart rate and more forceful heart muscle contractions.

Bone Bank: Facility used to obtain bone for implantation.

Bone Graft: Piece of bone used to take the place of removed tissue.

Bone spur: Bony growth or rough edges of bone.

Brain: The primary center that regulates and coordinates your body’s activities. Each part of the brain contr ols different aspects of your body’s functions. It’s the portion of the brain and spinal cord (central nervous system) that’s contained inside the skull.

Carotid artery disease: A disorder affecting one of the major blood vessels that carry blood to the head and neck. Tissue called plaque can accumulate on the walls of these blood vessels causing a narrowing that interferes with blood flow.

Carpal tunnel syndrome: A painful condition that occurs when the tendons in the wrist are inflamed after being aggravated by repetitive movements. It may cause progressive narrowing of the carpal wrist tunnel, resulting in nerve pressure and pain. Treatment for carpal tunnel syndrome includes rest, the use of a wrist splint during sleep or a relatively short operative procedure under local anesthesia relieving pressure on the affected nerve.

CAT scan: A radiologic study using x rays to provide pictures of the brain, spine, or spinal cord. Can also be used for other parts of the body.

Causalgia: An intense burning pain following an injury to a sensory nerve.

Cephalalgia and Cephalodynia: A headache or pain in the head.

Cerebral anoxia: An abnormal condition in which oxygen is deficient in brain tissue. If this condition continues for more than four to six minutes, irreversible brain damage may occur.

Cerebral contusion: A bruising of brain tissue as a result of a head injury.

Cerebral palsy: A motor function disorder caused by a permanent, non-progressive brain defect or lesion present at birth or shortly thereafter. It is characterized by spasticity, athetosis, tremors, and loss of muscle tone.

Cerebellum: The second largest part of the brain, located beneath the posterior part of the cerebrum.

Cerebrum: The largest portion of the brain. It is responsible for all thought, judgment, memory association and discrimination. The cerebrum is the uppermost portion of the brain. It is divided at the very top, forming the left and right hemispheres. Each hemisphere is divided into four lobes (frontal, occipital, parietal and temporal).

Cerebrospinal fluid: This is a clear, colorless, watery fluid produced by special capillaries within the ventricles of the brain. The fluid flows throughout the brain and around the spinal cord, and functions to cushion for these organs from shock or injury.

Cerebrovascular accident: Also known as a stoke or apoplexy, is the general term used to indicate that the blood supply to a portion of the brain has been suddenly shut off.

Cervical spine: The neck region of the spine containing the first seven vertebrae.

Cervical spine disorders: Conditions that cause constant pain in the ne ck or shoulder, tingling or numbness in the arms or weakness when using arms or hands.

Chemonucleolysis: The process of dissolving part of the nucleus of an intervertebral disk by the injection of a chemolytic agent.

Coccyx: More commonly known as the tailbone, this is a bony structure in the region of the spine below the sacrum.

Coma: A profound (deep) state of unconsciousness characterized by the absence of spontaneous eye movements, r esponse to painful stimuli, and vocalization. Comatose refers to one who is in a coma.

Concussion: This is sometimes referred to as a brain concussion or a cerebral concussion. It is a violent shaking or jarring of the brain caused by a direct blow or explosion.

Corpectomy: A surgigal procedure performed in the front of the neck that involves removal of a part of the vertebral body to relieve pressure on the spinal cord or nerve roots.

Cranial hematoma: A collection of blood trapped in the tissues of the brain. Cranial hematomas include epidural hematoma, subdural hematoma, and intracerebral hematoma.

Cranial nerves: The 12 pairs of cranial nerves originate from the undersurface of the brain and are arranged in identical pairs so both nerves of a pair are identical in function and structure. The cranial nerves are generally named for the area or function they serve and are identified with Roman numerals.
I Olfactory Nerves conduct impulses from receptors in the nose to the brain and are sensory in function.
II Optic Nerves conduct impulses from receptors in the eyes to thebrain and are sensory in function.
III Oculomotor Nerves send motor impulses to four of the external eye muscles and to certain internal eye muscles.
IV Trochlear Nerves send motor impulses to one external eye muscle of each eye.
V Trigeminal Nerves each divide into three branches: Ophthalmic branches go to the eyes and forehead. Maxillary branches go to the upper jaw. Mandibular branches go to the lower jaw.
VI Abducens Nerves innervate the muscles that turn the eye to the side.
VII Facial Nerves innervate the facial muscles, salivary glands, lacrimal glands, and the sensation of taste on the anterior two-thirds of the tongue.
VIII Acoustic Nerves each divide into two branches: Cochlear branches are concerned with the sense of hearing. Vestibular branches are concerned with the sense of balance.
IX Glossopharyngeal Nerves innervate the parotid glands and the sense of taste on the posterior third of the tongue and part of the pharynx.
X Vagus Nerves innervate part of the pharynx, larynx, vocal cords, and parts of the thoracic and abdominal viscera.
XI Spinal Accessory Nerves innervate the shoulder muscles. Some fibers of these nerves arise from the spinal cord.
XII Hypoglossal Nerves primarily innervate the muscles concerned with movements of the tongue.

Craniectomy: The surgical removal of a portion of the skull.

Craniocele: The herniation of brain substance through the skull.

Cranioplasty: The surgical repair of the skull.

Craniotomy: A surgical incision or opening into the skull.


Delirium: A mental state in which one experiences confusion and decreased awareness of surroundings.

Disc (Intervertebral): The tough, elastic 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: Deterioration of a disc. A disc in the cervical spine may deteriorate or wear out over time.

Diskectomy: The surgical removal of part or all of an intervertebral disc. It is performed to relieve pressure on a nerve root or the spinal cord.

Dysphasia: An impairment of speech due to a brain lesion. (A lesion is an injury or pathological change in the tissue.)

Echoencephalography: This is a diagnostic technique in which pulses of ultrasonic waves are beamed through the head from both sides.

Electroencephalography: This procedure is also known as EEG. It is the process of recording brain wave activity. The resulting record is called an electroencephalogram.

Encephalography: This is an x-ray study demonstrating the intracranial fluid-containing spaces of the brain. The resulting record is called an encephalogram.

Encephalitis: An inflammation of the brain.

Encephalopathy: Any degenerative disease of the brain.

Epilepsy: A disorder that causes abnormal electrical discharges in the brain. Normally, millions of electrical impulses pass between brain cells, sending messages that control movement, speech and thought. In epilepsy, these electr ical impulses are interrupted by sudden bursts of activity that result in seizures. Epilepsy may be treated with drug therapy and / or surgery.

Epidural Nerve Block: A spinal injection to the area of a pinched nerve; used to alleviate pain in the distribution of that nerve.

Excision: Removal by cutting away material, as in removing a disc.

Fissure: Also known as sulci, are the normal depressions or grooves of the cerebral cortex.

Foramen: A normally occurring opening or passage in the vertebrae of the spine through which the spinal nerve roots pass.

Foraminotomy: Enlargement of a foramen; may accompany a laminectomy.

Frontal Lobe: Controls motor functions.

Ganglion: A knot-like mass or group of nerve cell bodies located outside the central nervous system.

Glioma: A tumor of the brain/spinal cord that arises from any of several supporting cells (but not nerve cells) of the brain.

Grand mal seizure: Involves generalized involuntary muscular spasms.

Hallucination: A sense perception (sight, touch, sound, smell, or taste) that has no basis in external stimulation.

Head injury: Commonly referred to as traumatic brain injury, head injury is a major health problem commonly occurring in teens and young adults. The most common effects of a head injury are a hematoma (blood clot in the brain) or contusion (“bruised” brain).

Herniated disc: A break in the cartilage surrounding a disc in the spine, causing pressure on spinal nerves that produce pain down the legs. It is usually preceded by an episode of low back pain or a long history of intermittent episodes of back pain.

Hydrocephalus: A disorder in which too much spinal fluid, usually under high pressure, accumulates in the cavities of the brain. This can be caused by a birth defect, brain tumor, infection, hemorrhage or brain injury.

Hyperesthesia: A condition of excessive sensitivity to stimuli.

Innervation: The supply of nerves to a body part. It also means the stimulation of a body part through the action of nerves.

Instrumentation: The use of instruments in surgery that may include plating of screws for stabilization.

Lamina: The flattened or arched part of the vertebral arch, forming the roof of the spinal canal.

Laminectomy: Surgical removal of the rear part of a vertebra in order to gain access to the spinal cord or nerve roots, to remove tumors, to treat injuries to the spine, or to relieve pressure on a nerve root.

Lethargy: A state of being indifferent, apathetic, or sluggish.

Ligament: Fibrous connective tissue that links together bones at joints or between vertebrae of the spine.

Low back pain: The second most common cause of chronic pain after headaches. Causes include disc herniation, spinal stenosis, tumors, infections and inflammatory diseases.

Lumbago: A non-medical term signifying pa in in the lumbar region.

Lumbar: The lumbar spine consists of five vertebrae in the lower part of the spine between the ribs and the pelvis.

Lumbar spinal stenosis: A narrowing of the spinal canal that may result in nerve compression, and pain that travels from the lumbar spine into the legs. Treatment can be either conservative or surgical. Conservative treatments include non-steroidal anti-inflammatory medication, physical therapy and epidural steroid injections.

Macroencephaly: A condition in which the head is abnormally large.

Meninges: Three layers of connective tissue membrane that enclose the brain and spinal cord.

Meningitis: An inflammation of the meninges of the brain or spinal cord.

Meningopathy: Any disease of the meninges.

Microencephaly: A condition in which the head is abnormally small.

Migraine Headache: A syndrome characterized by sudden, severe, sharp headache usually present only on one side.

MRI: The radiologic study that provides intricate and detailed pictures of the spine, brain, spinal cord with the use of magnetic resonance images rather than x-rays. MRIs are used for many body parts needing detailed images. This provides the greatest detail other than physically looking inside the bony.

Multiple sclerosis: A progressive disease characterized by scattered patches of demyelination of nerve fibers of the brain and spinal cord. Demyelination is the destruction or loss of the myelin sheath from myelinated fibers.)

Myelinated: having a myelin sheath. Nerves that do not have the myelin sheath are gray, and th ey make up the “gray matter” of the brain and spinal cord.

Myelitis: An inflammation of the spinal cord.

Myelography: The diagnostic study of the spinal cord after injecting a contrast medium. The resulting record is called a myelogram.

Myelopathy: Symptoms related to spinal cord compression; typically involves both arms and/or legs including pain, weakness, coordination and may also affect bowel/bladder control.

Myelosis: Means a tumor of the spinal cord. However, it also means an abnormal proliferation of bone marrow tissue.


Narcolepsy: A syndrome characterized by recurrent uncontrollable seizures of drowsiness and sleep.

Nerve roots: The initial portion of a spinal nerve; the nerve root is an extension of the central nervous system that begins at the spinal canal and ends in the extremities (fingers, toes). Its purpose is to send sensory information from the extremity to the brain, and motor commands from the brain to the extremity.

Nerves: Fibers that conduct electrical impulses (messages) from the brain and spinal cord to all other parts of the body.

Nervous system: The nervous system is often described as being divided into the following parts: Central Nervous System that consists of the brain and spinal cord. Peripheral Nervous System that consists of the cranial nerves (extending from the brain) and spinal nerves (extending from the spinal cord). Autonomic Nervous System that consists of ganglia on either side of the spinal cord.

Neuralgia: Pain in a nerve or nerves.

Neuritis: An inflammation of a nerve or nerves. (The term neuritis and neuralgia are often used interchangeably.)

Neuropathy: Any disease of the nervous system.

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

Neurotransmitter: A neurotransmitter is a chemical substance that makes it possible for the impulse to jump across the synapse from one neuron to another.

Neuroglia: The supportive and connective cells of the nervous system. Sometimes called “nerve glue”.

Neuron: The basic cell of the nervous system. The three types of neurons are described according to their function. Efferent neurons, also known as “motor neurons”, carry impulses away from the brain and spinal cord and toward the muscles and glands. Afferent neurons, also known as “sensory neurons”, emerge from the skin or sense organs and carry impulses toward the brain and spinal cord. Connecting neurons, also called “associative neurons& quot;, carry impulses from one neuron to another. Each neuron consists of a cell body, several dendrites, a single axon, and terminal end fibers.

Occipital lobe: Controls eyesight.

Osteoporosis: A disorder in which bone is abnormally brittle and less dense; may result from a number of different diseases and abnormalities. Most commonly affects elderly women.

Paresthesia: An abnormal sensation, such as burning, tingling, or numbness, for no apparent reason.

Parkinson’s disease: A slowly progressing disorder caused by damage to brain cells. Symptoms include tremor, or involuntary and rhythmic movements of the hands, arms, legs and jaw, stiffness of the limbs, loss of spontaneous movement and an unsteady walk.

Parietal lobe: Receives and interprets nerve impulses from the sensory receptors.

Percutaneous diskectomy: A procedure where a thin tube is inserted through the skin of the back to suck out the ruptured disk or to vaporize it with a laser.

Peripheral nervous system: Includes the cranial and spinal nerves.

Petit Mal Seizure: A sudden, momentary loss of conciousness.

Physical therapy: A form of treatment consisting of excercising specific parts of the body such as the back, 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.

Pituitary tumors: Growths in the pituitary gland, which rests at the base of the brain. Pituitary tumors can vary in size and behavior. Treatment can be conservative with observation, imaging, medications or surgical removal of the tumor.

Poliomyelitis: This condition is also known as polio. It is a viral infection of the gray matter of the spinal cord that may result in paralysis. Individuals who have had poliomyelitis, and have recovered from it, may suffer from the post-polio syndrome which is the recurrence later in life of some polio symptoms.

Pons: The part of the brain stem situated at the base of the brain where nerve cells cross from one side of the brain to control the opposite side of the body.

Posterior: The back of the body.

Radiculitis: An inflammation of the root of a spinal nerve, especially that portion of the root that lies between the spinal cord and intervertebral canal.

Radiculopathy: Pain in the distribution of a single nerve. Manifested usually as arm or leg pain. Typically from a herniated disc in the back or neck; aka “pinched nerve”.

Receptors: The sensory organs (eyes, ears, skin, and taste buds) that receive external stimulation and transmit it to the sensory neurons.


Seizure: Also known as a convulsion, is a sudden, violent, involuntary contraction of a group of muscles. It may be accompanied by a loss of consciousness.

Sciatica: A lay term indicating pain along the course of the sciatic nerve, especially noted in the buttocks and back of the leg, thigh, and below the knee.

Somnambulism: Also known as noctambulism or sleepwalking, is the condition of walking without awakening.

Somnolence: Sleepiness and also an unnatural drowsiness. A somnolent person can usually be aroused by verbal stimuli.

Spasticity: Uncontrolled contractions of the skeletal muscles.

Spina bifida: Occurs during the third and fourth weeks of pregnancy, when a portion of the fetal spinal cord fails to close properly. As a result, the child is born with a part of the spinal nerve roots protruding from the back. With early treatment, the child can lead an active and productive life.

Spinal canal: A channel located in the vertebral column that protects the spinal cord.

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 is also a center for carrying out and coordinating reflex actions independently of the brain.

Spinal cord injuries: Commonly referred to as “broken neck or back”, spinal cord injuries can lead to paralysis and loss of motor function in the arms and legs. Correction of long defects associated with spinal cord injury can improve neurologic function.

Spinal fusion: A procedure in which bone is grafted onto the spine and in which instrumentation such as plates, screws and rods may be used to provide additional spinal support.

Spinal nerves: Consists of 31 pairs of nerves and are usually named after the artery the accompany or the body part they innervate.

Spinal stenosis: Narrowing of the vertebral column, resulting in pressure on the spinal cord, spinal sac, or nerve roots arising from the spinal cord.

Spine: The flexible bone column extending from the base of the skull to the tailbone. It is made of 33 bones known as vertebrae. The spine is also referred to as the vertebral column, spinal column or backbone. Here is an illustration of the bones of the spine (vertebrae) from the front and side.

Spinal Cord: Major bundle of nerves of the central nervous system located in the vertebral canal (back).

Spondylitis: Inflammation of vertebrae.

Spondylolisthesis: The forward displacement of one vertebra on another.

Stroke: Caused when normal blood supply to the brain is interrupted. This can happen by a blood clot (ischemic stroke) or bleeding in the brain (hemorrhagic stroke). Warning signs include an unusually severe headache, memory loss, numbness in the arm, slurred speech, loss of vision, poor balance or lack of coordination. Early diagnosis is key to successful treatment.

Stupor: A state of lethargy and unresponsiveness in which a person seems unaware of surroundings.

Sympathetic nervous system: The sympathetic division of the autonomic nervous system is concerned with body functions under stress. Receptors in the sympathetic nervous system are classified as being alpha or beta receptors.

Synapse: The space between two neurons or between a neuron and receptor organ.

Syncope: Also known as fainting, is a brief loss of consciousness caused by transient cerebral hypoxia. (Hypoxia is a lack of cellular oxygen.)

Temporal lobe: Controls the senses of hearing and smell.

Tic douloureux: Also known as trigeminal neuralgia or trifacial neuralgia, is an inflammation of the trigeminal (fifth cranial) nerve. It is characterized by sudden, intense, sharp pain on one side of the face.

Tremor: Involuntary shaking or trembling of the body or any of its parts.

Tremors of the brain and spinal cord: Symptoms and signs occur due to pressure on neural structures, with resultant irritation or destruction.

Trigeminal ne uralgia: A disorder of the facial nerve, which may cause painful spasms. Pain may be so severe it causes an involuntary frown to “tic”.

Tumor: An abnormal mass of cells.

Ventricle: A small cavity, such as the ventricles of the brain and heart.

Ventriculography: This is a form of encephalography. It’s a procedure for the radiographic visualization of the head after the injection of air or another contrast medium into the cerebral ventricles. Ventriculography also describes a radiographic study of a heart ventricle after the injection of a contrast medium.

Vertebrae: The 33 bones composing the spine. Individually referred to as a vertebra. They are divided into the cervical spine (neck), thoracic spine (upper body or rib cage), and lumbar spine (lower back), and the sacral spine (base of the spine).

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