thalamus (redirected from thalami)

thalamus /thal·a·mus/ (thal´ah-mus) pl. thal´ami   [L.] either of two large ovoid masses, consisting chiefly of gray substance, situated one on either side of and forming part of the lateral wall of the third ventricle. Each is divided into dorsal and ventral parts; the term thalamus without a modifier usually refers to the dorsal thalamus, which functions as a relay center for sensory impulses to the cerebral cortex.

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optic thalamus  lateral geniculate body.

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thal·a·mus (thl-ms)

n. pl. thal·a·mi (-m)

A large ovoid mass of gray matter that forms the larger dorsal subdivision of the diencephalon and is located medial to the internal capsule and to the body and tail of the caudate nucleus. It functions in the relay of sensory impulses to the cerebral cortex.

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tha·lamic (th-lmk) adj.

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Thalamus

A large oval area of gray matter within the brain that relays nerve impulses from the basal ganglia to the cerebellum, both parts of the brain that control and regulate muscle movement.

Mentioned in: Neurologic Exam, Tremors

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thalamus

[thal′əməs] pl. thalami

Etymology: Gk, thalamos, chamber

one of a pair of large oval nervous structures made of gray matter and forming most of the lateral walls of the third ventricle of the brain and part of the diencephalon. It relays sensory information, excluding smell, to the cerebral cortex. It is composed mainly of gray substance and translates impulses from appropriate receptors into crude sensations of pain, temperature, and touch. It also participates in associating sensory impulses with pleasant and unpleasant feelings, in the arousal mechanisms of the body, and in the mechanisms that produce complex reflex movements. Compare epithalamus, hypothalamus, subthalamus. thalamic, adj.

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thalamus [thal´ah-mus] (L.)

either of two large ovoid structures (the dorsal thalamus or simply thalamus and the ventral thalamus) composed of gray matter and located at the base of the cerebrum. (See also brain.) adj., adj thalam´ic. The thalamus functions as a relay station in which sensory pathways of the spinal cord and brainstem form synapses on their way to the cerebral cortex. Specific locations in the thalamus are related to specific areas on the body surface and in the cerebral cortex. A sensory impulse from the body surface travels upward to the thalamus, where it is received as a primitive sensation and then is sent on to the cerebral cortex for interpretation as to location, character, and duration. The thalamus has numerous connections to other areas of the brain as well, and these are thought to be important in the integration of cerebral, cerebellar, and brainstem activity.

ventral thalamus the subthalamic tegmental region, a transitional region of the diencephalon interposed between the (dorsal) thalamus, the hypothalamus, and the tegmentum of the mesencephalon; it includes the subthalamic nucleus, Forel's fields, and the zona incerta. Called also subthalamus.

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thalamus (thal´mus),

n an ovoid mass in the brain immediately lateral to the third ventricle that serves as the principal relay and integration station for the sensory systems in the body.

thalassemia

n a hereditary, chronic, hemolytic anemia with erythroblastosis. A complex of hereditary disorders characterized by microcytosis and increased red blood cell destruction and often associated with abnormal hemoglobins and increased normal trace hemoglobins. These disorders are prevalent in people of Mediterranean, African, and Asian ancestry. Disorders include Cooley's anemia, Cooley's trait, hemoglobin H disease, Hb S-thalassemia, Hb Cthalassemia, and Hb E-thalassemia.

thalassemia major (Cooley's anemia, erythroblastic anemia, famil-ial erythroblastic anemia, hereditary microcytosis, Mediterranean anemia, Mediterranean disease),

n the severe homozygous form of thalassemia characterized by a marked microcytic hypochromic anemia, atypical nucleated red blood cells, marked increase in hemoglobin F, and skeletal changes (underdevelopment, mongoloid facies, anterior open bite).

thalassemia minor (Cooley's trait),

n a heterozygous form of thalassemia that is a carried state with relatively mild manifestations; α₂ hemoglobin is elevated.

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thalamus

pl. thalami [L.] either of two large ovoid structures composed of gray matter and situated at the base of the cerebrum.

The thalamus functions as a relay station in which sensory pathways of the spinal cord and brainstem form synapses on their way to the cerebral cortex. Specific locations in the thalamus are related to specific areas on the body surface and in the cerebral cortex. A sensory impulse from the body surface travels upward to the thalamus, where it is received as a primitive sensation and then is sent on to the cerebral cortex for interpretation as to location, character and duration.

The thalamus has numerous connections to other areas of the brain as well, and these are thought to be important in the integration of cerebral, cerebellar and brainstem activity.

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thalamus 

One of a pair of ovoid masses of grey substance that serves as a relay station for sensory stimuli to the cerebral cortex. It contains the lateral geniculate body, which is a continuation of the pulvinar and which is situated at the posterior end of the thalamus. See lateral geniculate bodies.