| pyramidal | 1. Of or pertaining to a pyramid; in the form of a a pyramid; pyramidical; as, pyramidal cleavage. "The mystic obelisks stand up Triangular, pyramidal." (Mrs. Browning) 2. <chemistry> Same as Tetragonal. <mathematics> Pyramidal numbers, certain series of figurate numbers expressing the number of balls or points that may be arranged in the form of pyramids. Thus 1, 4, 10, 20, 35, etc, are trangular pyramidal numbers; and 1, 5, 14, 30, 55, etc, are square pyramidal numbers. Origin: Cf. F. Pyramidal. <anatomy> One of the carpal bones. See Cuneiform, 2 . Source: Websters Dictionary (01 Mar 1998) |
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| pyramidal auricular muscle | <anatomy> An occasional prolongation of the fibres of the tragicus to the spina helicis. Synonym: musculus pyramidalis auriculae, Jung's muscle, pyramidal muscle of auricle. (05 Mar 2000) |
| pyramidal bone | A bone on the medial (ulnar) side of the proximal row of the carpus, articulating with the lunate, pisiform, and hamate. Synonym: os triquetrum, cubital bone, os pyramidale, os triangulare, pyramidal bone, pyramidale, three-cornered bone, triquetrum. (05 Mar 2000) |
| pyramidal cataract | A cone-shaped, anterior polar cataract. (05 Mar 2000) |
| pyramidal cell | <anatomy, neurology> Commonest nerve cells of the cerebral cortex. (18 Nov 1997) |
| pyramidal cell layer | Layer 3 of the cortex cerebri. Synonym: Meynert's layer. (05 Mar 2000) |
| pyramidal cells | Projection neurons in the cerebral cortex and the hippocampus. Pyramidal cells have a pyramid-shaped soma with the apex and an apical dendrite pointed toward the pial surface and other dendrites and an axon emerging from the base. The axons may have local collaterals but also project outside their cortical region. (12 Dec 1998) |
| pyramidal decussation | The intercrossing of the bundles of the pyramidal tracts at the lower border region of the medulla oblongata. Synonym: decussatio pyramidum, decussatio motoria, motor decussation. (05 Mar 2000) |
| pyramidal disease | A condition of the horse's foot in which there is exostosis of the extensor process of the third phalanx, with swelling and chronic inflammation at the coronary band on the anterior surface of the foot. Synonym: pyramidal disease. (05 Mar 2000) |
| pyramidal eminence | A conical projection posterior to the vestibular window in the middle ear; it is hollow and contains the stapedius muscle. Synonym: pyramid of tympanum, pyramidal eminence, pyramis tympani. (05 Mar 2000) |
| pyramidal fibres | The fibres that compose the pyramidal tract (corticospinalis). Synonym: fibrae corticospinales, corticospinal fibres, fibrae pyramidales. (05 Mar 2000) |
| pyramidal fracture | A fracture of the midfacial skeleton with the principal fracture lines meeting at an apex at or near the superior aspect of the nasal bones. Synonym: Le Fort II fracture. (05 Mar 2000) |
| pyramidal lobe of thyroid gland | <anatomy> An inconstant narrow lobe of the thyroid gland that arises from the upper border of the isthmus and extends upward, sometimes as far as the hyoid bone; it marks the point of continuity with the thyroglossal duct. Synonym: lobus pyramidalis glandulae thyroideae, Lallouette's pyramid, Morgagni's appendix, pyramid of thyroid. (05 Mar 2000) |
| pyramidal muscle | <anatomy, muscle> Origin, crest of pubis; insertion, lower portion of linea alba; action, makes linea alba tense; nerve supply, subcostal. Synonym: musculus pyramidalis, pyramidal muscle. (05 Mar 2000) |
| pyramidal muscle of auricle | <anatomy> An occasional prolongation of the fibres of the tragicus to the spina helicis. Synonym: musculus pyramidalis auriculae, Jung's muscle, pyramidal muscle of auricle. (05 Mar 2000) |
| anterior pyramidal fasciculus | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
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| anterior pyramidal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| crossed pyramidal tract | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| direct pyramidal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| lateral pyramidal fasciculus | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| lateral pyramidal tract | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |