1. A round, flat plate; any approximately flat circular structure. 2. SYN: lamella (2). 3. In dentistry, a circular piece of thin paper or other material, coated with an abrasive substance, used for cutting and polishing teeth and fillings. [L. discus; G. diskos, a quoit, d.]
- A disks SYN: A bands, under band.
- Airy d. the image of a circular blur formed by a distant point source of light on the retina because of diffraction by the edge of the pupillary aperture where the diameter of the image decreases as the aperture increases.
- anisotropic disks SYN: A bands, under band.
- articular d. [TA] a plate or ring of fibrocartilage attached to the joint capsule and separating the articular surfaces of the bones for a varying distance, sometimes completely; it serves to adapt two articular surfaces that are not entirely congruent. SYN: discus articularis [TA], fibrocartilago interarticularis, fibroplate, interarticular fibrocartilage, intraarticular cartilage (1).
- articular d. of acromioclavicular joint [TA] the articular d. of fibrocartilage usually found between the acromial end of the clavicle and the medial border of the acromion. SYN: discus articularis acromioclavicularis [TA], acromioclavicular d., Weitbrecht cartilage.
- articular d. of distal radioulnar joint [TA] the d. that holds together the distal ends of the radius and ulna; it is attached by its apex to a depression between the styloid process and distal surface of the head of the ulna, and by its base to the ridge separating the ulnar notch from the carpal surface of the radius. SYN: discus articularis radioulnaris distalis [TA], radioulnar d., radioulnar articular d., triangular cartilage, triangular d. of wrist, triquetrous cartilage (1).
- articular d. of sternoclavicular joint [TA] the fibrocartilaginous d. that subdivides the sternoclavicular joint into two cavities. SYN: discus articularis sternoclavicularis [TA], sternoclavicular d., sternoclavicular articular d..
- articular d. of temporomandibular joint [TA] the fibrocartilaginous plate that separates the joint into upper and lower cavities. SYN: discus articularis temporomandibularis [TA], mandibular d., temporomandibular articular d..
- blastodermic d. the aggregation of blastomeres of a telolecithal ovum after cleavage has occurred.
- Bowman disks disks resulting from transverse segmentation of striated muscular fiber treated with weak acids, certain alkaline solutions, or freezing.
- Burlew d. an abrasive-impregnated rubber wheel used in dentistry for polishing. SYN: Burlew wheel.
- choked d. SYN: papilledema.
- ciliary d. SYN: orbiculus ciliaris.
- cone disks membranous disks of flattened sacs about 14 nm thick that occur in the outer segment of cones of the retina.
- cuttlefish d. a circle of paper or thin plastic coated with ground cuttlefish bone; used, when attached to a mandrel and rotated by a dental handpiece, for fine smoothing and finishing of dental materials and tooth.
- diamond d. a steel d. with the cutting surface(s) covered with fine diamond chips, for use in a dental handpiece.
- emery disks disks of paper or other materials coated with emery powder used to abrade or smooth the surface of teeth or fillings.
- germinal d., germ d. the point in a telolecithal ovum where the embryo begins to be formed. SYN: embryonic d., germinal area, area germinativa.
- H d. SYN: H band.
- hair d. a richly innervated area of skin around a hair follicle, consisting of a thickened layer of epithelial cells in which ramify unmyelinated terminals of a single axon.
- Hensen d. SYN: H band.
- herniated d. protrusion of a degenerated or fragmented intervertebral d. into the intervertebral foramen with potential compression of a nerve root or into the spinal canal with potential compression of the cauda equina in the lumbar region or the spinal cord at higher levels. SYN: protruded d., ruptured d..
- I d. SYN: I band.
- intercalated d. a specialized intercellular attachment of cardiac muscle comprising gap junctions, fascia adherens, and occasionally desmosomes.
- intermediate d. SYN: Z line.
- interpubic d. SYN: interpubic d..
- intervertebral d. a d. interposed between the bodies of adjacent vertebrae. It is composed of an outer fibrous part (annulus fibrosus) that surrounds a central gelatinous mass (nucleus pulposus). SYN: discus intervertebralis [TA], fibrocartilago intervertebralis, intervertebral cartilage.
- isotropic d. SYN: I band.
- Newton d. a d. on which are seven colored sectors, each occupying proportionally the same space as the corresponding primary color in the spectrum; when the d. is rapidly rotated it appears white.
- optic d. [TA] an oval area of the ocular fundus devoid of light receptors where the axons of the retinal ganglion cell converge to form the optic nerve head; SYN: discus nervi optici [TA], blind spot (3), Mariotte blind spot, optic nerve head, optic papilla, papilla nervi optici, porus opticus.
- Placido da Costa d. SYN: keratoscope.
- proligerous d. SYN: cumulus oöphorus.
- protruded d. SYN: herniated d..
- Q disks SYN: A bands, under band.
- rod disks membranous disks of flattened sacs about 14 nm thick that occur in the outer segment of rods of the retina.
- ruptured d. SYN: herniated d..
- sandpaper disks disks of paper coated with various grits of silica; used to abrade or smooth the surface of teeth or dental materials.
- stenopeic d., stenopaic d. a metallic or other opaque d. with a narrow slit through which one looks; used as a test for astigmatism.
- stroboscopic d. a revolving d. that gives successive views of a moving object.
- transverse d. one of the dark transverse bands seen on examining a striated muscular fiber under the microscope.
- Z d. SYN: Z line.
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a) a mammalian blood cell
b) BLIND SPOT
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(disk) [L. discus quoit, from Gr. diskos] a circular or rounded flat plate; spelled also disc. See also subentries under disc.Medical dictionary. 2011.