babinski response - Extension (instead of flexion) of the toes on stimulation of the sole of the foot, occurring in persons with lesions of the pyramidal tract.
bacterial infection - Infection by minute, one-celled organisms which multiply by dividing in one or more directions.
basal ganglia - The site of the brain where the extrapyramidal system originates. Includes caudate nucleus, globus pallidus, and putamen; thalamus, subthalamus, substantia nigra, and red nucleus sometimes included.
basilar artery - An artery formed by the right and left vertebral arteries which supplies blood to parts of the cerebrum and cerebellum. It supplies blood to many brainstem structures and leads to the right and left posterior cerebral arteries.
basophil - A granular leukocyte with an irregularly shaped, relatively pale-staining nucleus with cytoplasm that contains coarse bluish-black granules of variable size. Basophils contain vasoactive amines, such as histamine and serotonin, which are released on appropriate stimulation.
bell's palsy - Unilateral facial paralysis of sudden onset, caused by a lesion of the facial nerve.
beta rhythm - Rhythmic waves in the electroencephalogram that have a smaller amplitude than alpha waves and have an average frequency of about 25 cps.
bilateral - Refers to using both sides of the body or extremities on both sides.
bilateral sensory stimulation - Stimulation of both sides of the body simultaneously, using touch, hearing, or vision, in order to determine whether an individual imperceives the stimulus on one side or the other.
bilateral transfer - Facilitation of performance of a task by one hand as a result of having practiced the task with the other hand.
biofeedback - The use of sensory feedback to help provide some self-control over autonomic functions, such as blood pressure.
biotechnology - In the most general terms, biotechnology describes guiding natural occurrences to develop useful products. More specifically, it involves using living organism to make products and solve problems.
bipolar disorder - A genetically determined condition characterized by extremes of moods, often to psychotic (cf) proportions. Mania may alternate with depression.
blepharospasm - Spasmodic and frequent blinking of the eyes (tonic spasm of the orbicularis oculi muscle).
blood-brain barrier - A process whereby certain substances fail to leave the blood circulation and enter the gray and white matter of the brain. The "barrier" is more of a physiological concept than a defined anatomic structure. In addition, the barrier does not exist at certain sites in the brain, including the pituitary gland, the pineal gland, and choroid plexus.
blood dyscrasia - A disorder characterized by an abnormal composition of the blood.
body dysgnosia - A deficit, associated with aphasia, in which the subject is impaired in ability to identify body parts.
bone - The hard form of connective tissue that makes up most of the skeleton. The organic component is comprised of cells and matrix, and the inorganic is mineral. The framework of the matrix is collagenous fibers, into which is integrated the mineral component of 85 percent calcium phosphate and 10 percent calcium carbonate, giving bone its firmness. Bone is also called osseous tissue.
bone scan - Radionuclide test usually performed in the radiology department. It can detect fractures, stress fractures, areas of infection in bone, abnormal bone growth, and bone cancer, and also spread of cancer to the bones.
bone window - Used for viewing bone structure and joints in CT scanning, it measures the spinal canal, detects fractures, and shows whether the fracture is displaced inside or outside the spinal canal.
bony end plate - One of the components of the vertebral discs. They are composed of two layers of cartilage that cover the top and the bottom surfaces of the disc. They are also called vertebral end plates.
bony union - Final stage of the bodyﾒs repair of a bone fracture.
bow string sign - Test similar to the Lasegueﾒs sign done in the following way: The patient is lying in bed. The examiner sits on the edge of the bed, flexes the patientﾒs thigh, and puts the patientﾒs legs over the examinerﾒs shoulder in an angulation in such a way that the patient is free of pain. Then, with a finger, the doctor presses the patientﾒs sciatic nerve behind the knee (popliteal area). If the patient complains that the pain radiates up to the back or down to the foot, the test is positive.
brachia pontis - A pair of peduncles which attach the pons to the overlying cerebellum.
brachial - Refers to the arm.
brachial plexus - Network or tangle of nerves originating from the ventral branches of the last four cervical spinal nerves and most of the ventral branch of the first thoracic spinal nerves. It situates partly in the neck and partly in the armpit area.
bradykinesis - A motor disorder, frequently seen in Parkinson's disease,resulting from rigidity of muscles and manifested by slow finger movements and difficulty in fine motor performance, such as writing.
bradykinin - Chain of nine amino acids; it is a powerful vasodilator that causes increased permeability. It constricts smooth muscle and stimulates pain receptors.
brain - That part of the central nervous system contained within the cranium, comprising the prosencephalon, mesencephalon, and rhombencephalon. It is developed from the frontal part of the embryonic neural tube. Also called encephalon from the Greek enkephalos, brain.
brain abscess - A localized collection of pus in a cavity in the brain, formed by the disintegration of tissues.
brain contusion - A bruise of brain tissue in which there is capillary bleeding.
brain death - A state of irreversible coma in which cerebral and brain stem functions are absent.
brain electrical activity mapping (BEAM) - A computerized interpretation of brain currents incorporating (usually) sound and visual evoked potentials to produce a colored map of brain electrical functioning.
brain infection - An invasion of brain tissues by pathogenic organisms in such a way that injury of brain tissue follows with symptoms of illness.
brain lesion - Any pathological or traumatic damage of brain tissue.
brain scan - Any A radionuclide test for measuring blood circulation through the brain, or for detecting tumors, infection, or evidence of stroke.
brain stem - Composed of midbrain, pons and medulla.
Broca's (motor or expressive) aphasia - A disturbance of speech or reading caused by a defect in the motor (afferent or affector) apparatus of the brain. Comprehension of speech is usually not affected.
Brown-Sequard syndrome - An incomplete cord injury that is difficult to diagnose and is characterized by paralysis and lack of sensation below the spinal cord injury. The paralysis of the extremity, with loss of discriminatory and joint sensation, is on the side where the spinal cord has been injured. Loss of sensation of pain and temperature is on the opposite side.
bruit - A sound or murmur, especially of an abnormal nature, that is heard in auscultation.
bruxism - Tooth grinding, often associated with emotional tension or a temporomandibular joint disorder.
bulging disc - Delineation abnormality in the intervertebral disc as seen in X-rays. It is subject to various interpretations, and sometimes causes communication difficulties. In simple terms, it refers to a diffuse protrusion of disc material beyond the back margins of the vertebral endplates without significant irregularity or degree of focus. The outer fibers of the annulus fibrosus are intact.
burst fracture - A fracture of the interior and middle vertebral bodies.
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