| pyramid of light | A triangular area at the anterior inferior part of the tympanic membrane, running from the umbo to the periphery, where there is seen a bright reflection of light. Synonym: cone of light, light reflex, Politzer's luminous cone, red reflex, Wilde's triangle. Malacarne's pyramid, a lobule on the undersurface of the cerebellum, the posterior portion of the vermis. (05 Mar 2000) |
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| pyramid of medulla oblongata | An elongated, white prominence on the ventral surface of the medulla oblongata on either side along the anterior median fissure, corresponding to the pyramidal tract. Synonym: pyramis medullae oblongatae, anterior column of medulla oblongata, anterior pyramid. (05 Mar 2000) |
| pyramid of thyroid | <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) |
| pyramid of tympanum | 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) |
| pyramid of vermis | A subdivision of the inferior vermis of the cerebellum between the tuber and the uvula. Synonym: pyramis vermis, cerebellar pyramid. Pyramid of vestibule, the upper triangular extremity of the crista vestibuli. Synonym: pyramis vestibuli. (05 Mar 2000) |
| pyramid sign | <clinical sign> Any of the symptoms indicating a morbid condition of the pyramidal tracts, such as the Babinski or Gordon sign, spastic spinal paralysis, foot clonus, etc. (05 Mar 2000) |
| 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) |
| 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) |