| pyramid | 1. A solid body standing on a triangular, square, or polygonal base, and terminating in a point at the top; especially, a structure or edifice of this shape. 2. <geometry> A solid figure contained by a plane rectilineal figure as base and several triangles which have a common vertex and whose bases are sides of the base. 3. The game of pool in which the balls are placed in the form of a triangle at spot. <geometry> Altitude of a pyramid a pyramid whose axis is perpendicular to the base. Origin: L. Pyramis, -idis, fr. Gr, of Egyptian origin: cf. F. Pyramide. Source: Websters Dictionary (01 Mar 1998) |
|---|---|
| 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) |
| 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) |
| anterior pyramid | 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) |
|---|---|
| base of renal pyramid | The outer broad part of a renal pyramid that lies next to the cortex. Synonym: basis pyramidis renis. (05 Mar 2000) |
| malpighian pyramid | One of a number of pyramidal masses seen on longitudinal section of the kidney; collectively, they constitute the renal medulla, and contain part of the secreting tubules and the collecting tubules. Synonym: pyramis renalis, malpighian pyramid, medullary pyramid. (05 Mar 2000) |
| renal pyramid | One of a number of pyramidal masses seen on longitudinal section of the kidney; collectively, they constitute the renal medulla, and contain part of the secreting tubules and the collecting tubules. Synonym: pyramis renalis, malpighian pyramid, medullary pyramid. (05 Mar 2000) |
| medullary pyramid | One of a number of pyramidal masses seen on longitudinal section of the kidney; collectively, they constitute the renal medulla, and contain part of the secreting tubules and the collecting tubules. Synonym: pyramis renalis, malpighian pyramid, medullary pyramid. (05 Mar 2000) |
| cerebellar pyramid | 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) |
| petrous pyramid | The part of the temporal bone that contains the structures of the inner ear and the second part of the internal carotid artery; in antenatal life it appears as a separate ossification centre. Synonym: pars petrosa ossis temporalis, periotic bone, petrosal bone, petrous pyramid. (05 Mar 2000) |
| population pyramid | <epidemiology> Graphical representation of the age and sex composition of a population, constructed by computing the percentage distribution of the population in each age and sex class. (05 Mar 2000) |
| posterior pyramid of the medulla | gracile fasciculus |
| olfactory pyramid | A small area of gray matter situated between the roots of the olfactory tracts; it is continuous caudally with the anterior perforated substance. (05 Mar 2000) |
| Ferrein's pyramid | The centre of the renal lobule, which has the shape of a small, steep pyramid, consisting of straight tubular parts; these may be either ascending or descending limbs of the nephronic loop or collecting tubules. Synonym: pars radiata lobuli corticalis renis, Ferrein's pyramid, processus ferreini. (05 Mar 2000) |
| Lallouette's pyramid | <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) |