MEDICAL GLOSSARY

Abduction: Movement of an arm or leg away from the body.
Acute: Having rapid onset, severe symptoms, and a short course. Not chronic.
Adduction: Movement of an arm or leg toward the body.
Adhesions: Tissue surfaces that are adherent or attached to each other, either loosely or firmly,
as a result of wound healing and sometimes inflammation.
Amyotrophic: Muscle wasting.
Anomaly: A deviation from the average or norm. Anything structurally unusual or irregular i.e.,
presence of an extra finger or absence of a limb or congenital malformation.
Anterior: Pertaining to the front of the body.
Antiemetics: Medication to stop or prevent vomiting.
Apnea: Cessation of breathing. Skin color changes, pallor and/or cyanosis may ensue. There is
a lack of chest wall movement. Can be caused by compression of the brainstem or lower cranial
nerves.
Arachnoid: Delicate, web-like middle layer of the three membrane layers that cover the brain
and spinal cord; arachnoid mater. Named after a spider web.
Arachnoiditis: Inflammation of the arachnoid membrane.
Ascending tracts: Groups of nerve fibers in the spinal cord that transmit sensory impulses
upward to the brain.
Aseptic: Sterile, without bacteria; living pathogenic organisms are absent.
Aseptic meningitis: Inflammation of the membranes (meninges) that cover the brain and spinal
cord. NOT an infection.
Aspiration: The act of withdrawing a fluid from the body by a suction device. Inspiratory
sucking into the airways of fluid or foreign body, such as vomit.
Astrocytes: A type of neuroglial cell that functions to connect neurons to blood vessels.
Asymptomatic: Without symptoms, or producing no symptoms.
Ataxia: Impaired ability to coordinate the muscles in voluntary muscular movements;
symptomatic of any of several disorders of the nervous system.
Atrophy: A wasting of tissues or decrease in size of a part of the body because of disease or
other influences.
Atypical: Not typical.
Autonomic nervous system: Portion of the nervous system that functions to control the actions
of the visceral organs and skin; its actions are not under voluntary control.
Axon: A nerve fiber that conducts a nerve impulse away from a neuron cell body.
Barium swallow: An x-ray using barium to view the act of swallowing, the esophagus or
stomach. It can show if a person may be aspirating.
Basal ganglion: Mass of gray matter located deep within a cerebral hemisphere of the brain;
has important functions in automatic movements of the limbs and in the control of muscle
tonus.
Basilar impression: Upward displacement, particularly of the uppermost part of the cervical
spine, into the region of the posterior fossa often producing compression of the brainstem and
portions of the cerebellum.
Bilateral: Something that occurs or appears on both sides. A patient with equal strength
bilaterally means there is equal strength on both sides of the body.
Brainstem: The portion of the brain that includes the midbrain, pons and medulla, thalamus and
hypothalamus.
Calamus sciptorius: Inferior part of the rhomboid fossa; the pointed lower end of the fourth
ventricle of the brain. It is shaped like a pen and lies between the restiform bodies.
Canalization neurulation: The formation of canals or passages to form the neural tube during
the early stages of embryonic development.
Catheter: A tube designed for insertion into vessels, canals, passageways or body cavities to
permit the injection or withdrawal of fluids or substances. It can also be used to keep a
passageway open.
Caudal: Toward the lower end of the spine.
Central canal: The opening or channel normally present through the length of the spinal cord
in later fetal life and early infancy. It gradually disappears throughout childhood, but segments
of it may remain in adults (see also hydromyelia).
Central nervous system: The part of the nervous system consisting of the brain and spinal
cord, which coordinates the entire nervous system of the body.
Cerebellar cortex: The outer layer of the cerebellum.
Cerebellar speech: Abnormal speech patterns seen in people who have a disease of the
cerebellum or its connections; a slow, jerky and slurred speech that may come and go or it may
be unvaried in pitch.
Cerebellar tonsils: Normal downward extensions of each cerebellar hemisphere.
Cerebellomedullary: Refers to the connections of the cerebellum and the medulla.
Cerebellum: Portion of the brain that lies in the posterior fossa and coordinates skeletal muscle
movement.
Cerebral aqueduct: A narrow conduit or passage between the third and fourth ventricles
located in the midbrain. CSF moves from the third ventricle through the cerebral aqueduct to
the fourth ventricle.
Cerebral cortex: The outer layer of the cerebrum.
Cerebral hemisphere: One of the large paired structures that together constitute the cerebrum
of the brain.
Cerebral spinal fluid: Fluid occupying the ventricles of the brain, subarachnoid space of the
meninges, and the central canal of the spinal cord.
Cerebrum: Portion of the brain that occupies the upper part of the cranial cavity.
Cervical: The area of the neck made up of seven cervical vertebrae, which are counted from
top to bottom. The top is C1, the first cervical vertebra, followed by C2, C3, etc.
Charcot joint: A type of diseased joint associated with varied conditions, syringomyelia among
them, which involves disease or injury to the spinal cord. Because normal pain sensation of the
joint is impaired, the pain mechanisms that protect the joint are diminished or absent. As a
result, the joint may undergo relatively painless severe degenerative changes with deformity.
Chiari malformation: Descent of the brainstem and lower cerebellum through the foramen
magnum into the cervical vertebral canal.
Choroid plexus: Mass of specialized capillaries that lie in the ventricles of the brain; these
vascular tissue tufts produce cerebral spinal fluid from blood.
Chronic: Long-lasting; a disease having protracted course, not acute.
Cine MRI: Test performed in the MRI scanner that looks at the flow of CSF around the
cerebellum and into the spinal canal.
Cisterna magna: Widened area of the subarachnoid space located between the cerebellum
and the medulla. It receives CSF from the fourth ventricle through the foramen of Magendie
and foramina of Luschka.
Clonus: A series of alternating muscle contractions and partial relaxations that produces a
jerking spasm of a limb, most often seen at the ankle, indicative of a brain or spinal cord
abnormality involving motor pathways.
CM: See Chiari malformation.
CNS: See central nervous system.
Coele or cele: Related to a cavity or space.
Congenital: Existing at birth, usually refers to certain mental or physical traits, peculiarities or
diseases; a more general term than hereditary since congenital includes conditions due to
influences arising during gestation.
Contraindicated: A medication or procedure that is not advisable i.e., tetracycline is
contraindicated during pregnancy.
Contrast: The difference between two areas in an image; a substance that selectively increases
the imaging signal of specific structures such as blood vessels or tumors.
Conus medullaris: The lowest end of the spinal cord.
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CHIARI MALFORMATION AND SYRINGOMYELIA 35
Cranial nerves: The 12 nerves of the brain that control motor and sensory functions, including
swallowing, heart rate, eye movement and smell.
Craniectomy: The excision (removal) of part of the skull.
CSF: See cerebral spinal fluid.
CT scan: A specialized radiographic technique in which many fine x-ray beams converge on
one small target area (pixel); a computer calculates the x-ray absorption of tissue in each pixel,
and converts this numerical value into a gray scale value; placing pixels of various shades of
gray into anatomic arrangement results in an anatomic image.
Cyanosis: Blue or purple color to the skin and mucous membranes resulting from insufficient
oxygen in the blood.
Dandy Walker Syndrome: A condition characterized by hydrocephalus in infants associated
with an abnormal closure of the foramina of Luschka and Magendie.
Decompression: To relieve or take pressure off.
Diencephalon: Portion of the brain in the region of the third ventricle that includes the
thalamus and hypothalamus.
Diplopia: Double vision; occurs when the two eyes are unable to fix (look at) the same point.
Dissociation of sensation: Loss of pain and temperature sensation while light touch sensation
is preserved.
Distal: Moving further from the midline or center of the body.
Dorsal: Posterior; pertains to the back of the body or of its parts, such as the spinal cord.
Dura mater: Tough outer layer of the membranes surrounding the brain and spinal cord.
Dysarthria: Speech that is difficult and poorly articulated; this may be caused by damage to
the cerebellum or its connections, or to injury to nerves involved in speech.
Dysequilibrium: Inability to maintain proper balance.
Dyesthesia: Alteration in sensation. Sensation of pins and needles, burning pain or unpleasant
exaggeration of normal sensation that may occur with or without skin stimulation.
Dysmetria: An inability to accurately control the range or force of muscle movement. Often
seen in cerebellar disorders.
Dysphagia: Inability or difficulty in swallowing.
Dysplastic tonsil: Abnormal development of a cerebellar tonsil. Each cerebellar hemisphere has
a downward extension called tonsil.
Dyspnea: Labored or difficult breathing resulting in air hunger.
Ectopia: Malposition or displacement of any organ or structure, congenital or acquired.
Edema: An excessive accumulation of fluid within tissues.
Elongated: To make or to grow longer.
Enuresis: Involuntary passage of urine, usually during sleep.
Epidural space: Space between the dura and the bone of the vertebral canal.
Esophagus: Muscular tube extending from the pharynx at the back of the throat to the
stomach.
Excision: To cut away a portion.
Extremity: A limb; an arm or leg.
Fascia lata graft: A graft-covering or repair of tissue with fascia, the fibrous membrane that
covers muscle over the lateral thigh.
Fasciculations: Involuntary contractions or twitching of groups of muscle fibers; a coarser form
of muscle contractions than fibrillation.
Filum terminale: A long, slender filament at the end of the spinal cord.
Foramen: An opening, usually in bone or organ or membrane (plural is foramina).
Foramen magnum: Large opening in the base of the skull through which the spinal cord
becomes continuous with the medulla oblongata.
Foramina of Luschka: Openings or passages for CSF on the lateral sides of the fourth ventricle.
Fossa: A depression or cavity within bone or surrounded by bone.
Fourth ventricle: Ventricle (a normal cavity) of the rhombencephalon of the brain; a cavity of
irregular tent-like shape extending from the obex upward to its communication with the sylvian
aqueduct, enclosed between the cerebellum and the rhombencephalic tegmentum. The
ventricle of the brain that lies between the cerebellum and the brainstem, it expresses CSF into
the subarachnoid space via the two lateral foramina of Luschka and the single medial foramen
of Magendie.
Gait: Manner of walking.
Gliogenous: Of the nature of neuroglia, glia – the tissue that forms the support element of cells
and fibers of the nervous system.
Gliosis: Proliferation (growth by reproduction) of the neuroglial tissue in the central nervous
system.
Greenstick fracture: A bone break in which the bone is bent but cracked only on the outside of
the bend.
Gyrus: One of the convolutions of the cerebral hemispheres of the brain. The upraised ridges of
the cerebrum.
Hemiplegia: Paralysis or severe weakness (paresis) of one side of the body, usually due to
injury or disease of the brain or spinal cord.
Hemivertebrae: A congenital absence of half of a vertebra.
Horner syndrome: A condition with constriction of the pupil, partial drooping of the eyelid,
recession of eyeball back into the socket, and sometimes loss of sweating over the affected side
of the face, due to paralysis of the cervical sympathetic nerve trunk. It is often incomplete, i.e.
not all the listed manifestations are present in one patient.
Hydro: Water, or collection of watery fluid.
Hydrocephalus: Enlargement of the normal cavities (ventricles) present in the brain. It may
result from impairment in outflow of CSF normally produced within the brain ventricles. It may
also result from developmental anomalies, infection, injury or brain tumors.
Hydromyelia: Accumulation of fluid in the enlarged central canal of the spinal cord.
Hyper: Prefix meaning above, excessive or beyond.
Hyperreflexia: Increase in action of the reflexes.
Hypo: Prefix meaning less than, below or under.
Hypoplasia: Defective development of tissue.
Hyporeflexia: Decrease in the action of the reflexes.
Hypotonia: Reduced tension, relaxation of arteries; loss of muscle tone.
ICP: See intracranial pressure.
Idiopathic: Pertaining to conditions without clear cause, as of spontaneous origins.
Impulse: A wave of depolarization conducted along a nerve fiber or muscle fiber.
Increased intracranial pressure: An increase in CSF production or blockage of CSF pathways
resulting in pressure on the brain. The skull cannot expand to accommodate the pressure, which
leads to symptoms such as headache.
Inferior: Situated below something else, pertaining to the lower surface of a part.
Insidious: A disease that develops without recognized symptoms so that the patient is
unaware of the onset of the disease.
Interpedicular spaces: Space between the pedicles of the vertebrae.
Invasive procedures: A medical procedure that necessitates entrance into the body as part of
the action required. Examples include needles introduced for injections and for lumbar
puncture, as well as all surgical procedures.
Ipsilateral: On the same side; affecting the same side of the body. Said of findings (paralysis)
appearing on the same side of the body as the brain or spinal cord lesion producing them.
Ischemia: A deficiency of blood in a part of the body.
Klippel Feil syndrome: Congenital anomaly characterized by a short wide neck, low hairline
and fusion of two or more cervical vertebrae. The central nervous system may be affected.
Kyphosis: One form of abnormal curvature of the spine. The condition of kyphosis of the
thoracic spine commonly called hunchback is an extreme form.
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CHIARI MALFORMATION AND SYRINGOMYELIA 37
Laminectomy: The surgical removal of the posterior arch (lamina) of a vertebra.
Larynx: Structure located between the pharynx and trachea that houses the vocal cords.
Lateral: Pertaining to the side of the body.
Magnetic resonance imaging: A scanner using magnetic energy that interacts with tissue to
yield clear black and white pictures, for example of the brain and spinal cord.
Medial: Toward or near the middle of the body.
Medulla oblongata: Portion of the brainstem located between the pons and the spinal cord.
Meninges: A group of three membranes that covers the brain and spinal cord. Closest to the
brain and spinal cord is the pia, then the arachnoid and the outermost covering is the dura.
Meningitis: Infection or swelling of the membranes (meninges) that cover the brain and spinal
cord.
Meningo: Refers to the meninges, membranes covering the brain and spinal cord.
Mesencephalon: The midbrain, one of three primitive cerebral sacs from which develop the
corpora quadrigemina, the crura cerebri and the aqueduct of Sylvius.
Microgyri: Abnormally small cerebral convolutions.
Morvans chorea type: A condition with irregular uncontrollable movements.
MRI: See Magnetic resonance imaging
Myelo: Refers to the spinal cord.
Myelodysplasia: Defective formation of the spinal cord.
Myelogram: Imaging technique of the spinal cord and nerve roots by use of a radiopaque
medium injected into the subarachnoid space, the fluid space surrounding the spinal cord.
Myelomeningocele: Form of spina bifida in which portions of the spinal cord and its
membranes protrude through the open space in the vertebral column.
Myelotomy: Surgical incision into the spinal cord.
Necrosis: Death of cells or areas of tissue surrounded by healthy tissue.
Neurovascular bundle: Structure consisting of a group of nerves and blood vessels lying in
direct contact with each other.
Nissen fundoplication: An operation of the fundus of the stomach which sutures the fundus of
the stomach to the esophagus as a treatment for gastric reflux.
Nuchal rigidity: Muscle stiffness in the back of the neck.
Nystagmus: Constant, involuntary, cyclical movement of the eyeball. Movement may be in any
direction; i.e. sideways, up, down or rotatory. May be present continually or only with looking in
a certain direction. May be due to congenital conditions, labyrinithine irritability or neurological
disease.
Obex: A thin, crescent-shaped band of tissue covering the Calamus scriptorius at the point of
convergence of the nervous tissue at the lower end of the fourth ventricle. The point on the
midline of the top surface of the medulla oblongata that marks the tail end of the fourth
ventricle.
Occipital: The back of the head.
Occipital bone: The cup-like bone at the back of the skull. It houses the occipital lobes of the
brain and the cerebellum; its lower edge makes up the back rim of the foramen magnum.
Opisthotonos: Involuntary backward arching of the head, neck or back with stiffening of the
entire body.
Papilledema: Swelling of the optic nerve at the point of entrace into the eyeball. Choked disk.
In general, considered a sign of increased ICP.
Paraparesis: Partial paralysis affecting the lower limbs.
Paraspinous muscles: Muscles on either side of the spine.
Paresthesia: Abnormal sensation such as numbness, prickling and tingling.
Paucity: Smallness or lower in number.
Peduncle: Stalk-like structures in the brain connecting different functioning areas.
Percutaneous aspiration: Drawing out through the skin.
Peritoneum: The membrane covering the visceral organs and lining the abdominal cavity.
Permeable: Capable of allowing passage of fluid or substances in solution.
Pia mater: The inner membrane of the meninges that encloses the brain and spinal cord.
Platybasia: A developmental anomaly of the skull or an acquired softening of the skull bones
so that the floor of the posterior cranial fossa bulges upward in the region adjacent to the
foramen magnum.
Pleura: The membranes covering the lungs and lining the inside of the chest cavity.
Pleural space: Space between the lungs and the inside lining of the chest cavity.
Polygyria: Excess of the normal number of convulutions of the brain.
Posterior: Toward the back of the body.
Posterior fossa: Concavity at the back of the skull wherein the cerebellum lies.
Posterior fossa angiogram: A study of the blood vessels of the back of the brain: cerebellum
and brainstem.
Prone: Lying horizontal with face down.
Proprioception: The sensory modality allowing awareness of posture, movement and changes
in equilibrium and the knowledge of position, weight, and resistance of an object in relation to
the body.
Proximal: Closer to the midline or origin; opposite of distal.
Pseudomeningocele: A pocket of cerebrospinal fluid that has formed in an area of previous
surgery as a result of an opening in the covering membranes of the spinal cord.
Ptosis: Drooping of the eyelid, often related to the third cranial nerve function; also applied to
the drooping of the cerebellum through a large skull opening.
Queckenstedt: A sign or maneuver used for diagnostic purposes. Upon compression of the
veins of the neck, unilaterally or bilaterally, CSF pressure measured by lumbar puncture rises
rapidly in healthy persons, and falls rapidly when pressure is released. In spinal canal block, the
pressure is scarcely affected by this procedure.
Reflex: A rapid automatic response mediated by the nervous system.
Reflux: A return or backwards flow. Regurgitation.
Respiratory distress: Difficulty breathing of any cause, including cardiac, pulmonary and
neurological problems.
Reticular formation: Groups of cells and fibers arranged in a diffuse network throughout the
brainstem. They fill and connect the tracts that ascend and descend through this area. They are
important in controlling or influencing alertness, wakefulness, sleeping and some other reflexes.
Rhomboencephalon: Primary division of the embryonic brain that gives rise to the
metencephalon and myelencephalon. It includes the pons, cerebellum and medulla oblongata.
Sometimes called the hindbrain.
Sagittal: A plane or section that divides a structure into right and left portions.
Scoliosis: A side-to-side curvature of the vertebral column.
Sensory: Pertaining to or conveying sensation (i.e. pain, touch, temperature).
Sheath: A covering structure, usually elongated.
Shunt: Passage constructed to divert flow of fluid when the normal pathways for the fluid are
either blocked or inadequate.
Skull series: A group of x-rays taken of the skull from various positions.
Sleep apnea: To stop breathing for brief periods while sleeping.
SM: See syringomyelia.
Somatosensory evoked potentials: An electrophysiological test often used during spinal cord
surgery to help determine whether conduction of electrical signals through the sensory
pathways of the spinal cord are impaired.
Spasticity: Stiffness or position that is difficult to release voluntarily.
Spina bifida: Failure of the spine to close properly during the first month of pregnancy. In severe
cases, the spinal cord protrudes through the back and may be covered by only skin or a thin
membrane. When there is no externally evident abnormality, referred to as spina bifida occulta.
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CHIARI MALFORMATION AND SYRINGOMYELIA 39
Stenosis: A constriction or narrowing of a passage.
Stent: A device used to maintain an opening into a cavity or to hold tissues in place during
healing.
Strabismus: Disorder in which the two eyes cannot be directed at the same object; when one
eye fixes upon a point (sees an object), the other eye deviates to some other point; vision in the
deviated eye is usually suppressed; if not, diplopia results; squint.
Stridor: A harsh sound made during respiration. It is high-pitched and sounds like the howling
of the wind. It is due to constriction of the air passages.
Subarachnoid space: The space within the meninges between the arachnoid mater and the pia
mater; it is normally filled with CSF.
Subcutaneous tissue: Tissue beneath the skin.
Suboccipital: Area beneath the back of the head; below the occipital bone.
Subperiosteal: Beneath the periosteum (the membrane covering of the bones).
Sulcus: A furrow, fissure or depression, especially of the brain. Many brain sulci have specific
names.
Supine: Lying on the back; a position.
Sylvian aqueduct: A narrow canal connecting the third to the fourth ventricle.
Syncope: Fainting, most often the result of inadequate circulation of blood to the brain.
Characterized by sudden pallor, coldness of the skin and partial or complete unconsciousness.
Syringo: Prefix used to denote a procedure or process originating in a syrinx cavity (example:
syringoperitoneal shunt).
Syringocoele or Syringocele: The central cavity or canal of the spinal cord continuous with the
fourth ventricle of the brain stem; used synonymously with central canal; also used for the
cavity in the ectopic cord in a myelomeningocele.
Syringomyelia: Chronic progressive disease of the spinal cord characterized by the
development of a fluid-filled cavity or cavities within the spinal cord. Cavitation can occur in any
area of the spinal cord. It can involve pathways of the cord that carry impulses of pain and
temperature sensations resulting in sensory losses. Pain and paresthesias also occur. Destruction
of lateral and anterior gray matter in the cord causes muscular atrophy, spastic paralysis and
weakness. Scoliosis is often found in association with syringomyelia.
Syringotomy: An operation to create an opening into a syrinx cavity.
Syrinx: A hollow cavity or tube. In medicine it refers to a fluid-filled cavity within the spinal
cord.
Telencephalon: The embryonic endbrain or the anterior division of the prosencephalon from
which the cerebral hemispheres, corpora striata and the rhinencephalon develop.
Tentorium: A tent-like structure or part. In the brain the tentorium cerebelli is the fold of the
dura mater that lies between the cerebellum and the cerebrum.
Tethered cord: Abnormal attachment and scarring of the spinal cord or its coverings
(meninges) can occur as the result of a developmental disorder such as a small mass of fatty
tissue, a tight filum terminale or a midline bone spur. Tethering results in loss of normal tiny
movements of the spinal cord inside its linings, and may place tension on the cord resulting in
cord injury. The spinal cord can also become adherent, i.e. tethered, by scar tissue that results
from injury, surgery or disease process.
Thoracic: The area of the back between the cervical and lumbar region comprised of
12 vertebrae.
Tinnitus: A ringing, tinkling or buzzing sound in the ear.
Torticollis: A stiff neck caused by spasms of the neck muscles drawing the head to one side
with the chin pointed to the other side. It may be congenital or acquired.
Trachea: Tubular organ that leads from the larynx to the bronchi.
Trachea malacia: Softening of the cartilage of the trachea.
Trophic: Concerning nourishment; applied to a type of nerve believed to control the growth
and nourishment of the parts they innervate (supply).
Unilateral: Pertaining to one side.
Ventral: Pertaining to the front of the body or its parts; the belly.
Ventricle: A cavity such as those normally present in the brain that are filled with
cerebrospinal fluid.
Ventriculography: An x-ray process used to visualize the size and shape of the brain’s
ventricles by injecting air or contrast to replace the CSF that normally fills this space.
Ventriculo-peritoneal Shunt: A shunt or tube inserted into the ventricles of the brain attached
to tubing that is placed into the abdominal (peritoneal) cavity to drain excess spinal fluid from
the brain.
Ventriculostomy: Establishment of an opening performed in the third ventricle to relieve
hydrocephalus.
Vermis: The normal midline portion of the cerebellum lying between the two cerebellar
hemispheres. Its outer surface appearance reminded early anatomists of a worm.
Visceral: Pertaining to one of the organs found in the skull, chest, abdomen or pelvis (brain,
lung, liver, etc.).
Weakness: Inability of muscles to perform their normal function. Weakness of the hands may
result in difficulty grasping objects; weakness of the legs may result in difficulty walking;
weakness of certain muscles in the pharynx may cause difficulty swallowing.