| orbicular process | A knob at the tip of the long limb of the incus which articulates with the stapes. Synonym: processus lenticularis incudis, lenticular apophysis, lenticular bone, orbicular bone, orbicular process, orbiculare, os orbiculare, os sylvii. (05 Mar 2000) |
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| cochleo-orbicular reflex | A form of the wink reflex in which there is a contraction, sometimes very slight, of the orbicularis palpebrarum muscle when a sudden noise is made close to the ear; it is absent in labyrinthine disease with total deafness. Synonym: acousticopalpebral reflex, auropalpebral reflex, cochleo-orbicular reflex, startle reflex. (05 Mar 2000) |
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| orbicular | Circular or nearly so. (09 Oct 1997) |
| orbicular bone | A knob at the tip of the long limb of the incus which articulates with the stapes. Synonym: processus lenticularis incudis, lenticular apophysis, lenticular bone, orbicular bone, orbicular process, orbiculare, os orbiculare, os sylvii. (05 Mar 2000) |
| orbicular ligament | <anatomy> One of a number of ligament's encircling various parts; the principal annular ligament's are those of the stapes, radius, and trachea. See: annular ligament of the radius, annular ligament of the stapes, annular ligaments of the trachea. Synonym: ligamentum annulare, orbicular ligament. (05 Mar 2000) |
| orbicular ligament of radius | The ligament that encircles and holds the head of the radius in the radial notch of the ulna, forming the proximal radioulnar joint and enabling pronation/supination of forearm; receives the radial collateral ligament of the elbow. Synonym: ligamentum annulare radii, ligamentum orbiculare radii, orbicular ligament of radius. (05 Mar 2000) |
| orbicular muscle | <anatomy> A sphincter-like sheet of muscle that encircles an orifice such as the mouth or the palpebral fissures. Synonym: musculus orbicularis, orbicular muscle, orbicularis. (05 Mar 2000) |
| orbicular muscle of eye | <anatomy> Consists of three portions: orbital part, or external portion, which arises from frontal process of maxilla and nasal process of frontal bone, encircles aperture of orbit, and is inserted near origin; palpebral part, or internal portion, which arises from medial palpebral ligament, passes through each eyelid, and is inserted into lateral palpebral raphe; lacrimal part (tensor tarsi muscle, Duverney's or Horner's muscle) arises from posterior lacrimal crest and passes across lacrimal sac to join palpebral portion; action, closes eye, wrinkles forehead vertically; nerve supply, facial. Synonym: musculus orbicularis oculi, musculus orbicularis palpebrarum, orbicular muscle of eye, sphincter oculi. (05 Mar 2000) |
| orbicular muscle of mouth | <anatomy, muscle> Origin, by nasolabial band from septum of the nose, by superior incisive bundle from incisor fossa of maxilla, by inferior incisive bundle from lower jaw each side of symphysis; insertion, fibres surround mouth between skin and mucous membrane of lips and cheeks, and are blended with other muscles; action, closes lips; nerve supply, facial. Synonym: musculus orbicularis oris, musculus sphincter oris, orbicular muscle of mouth, sphincter oris. (05 Mar 2000) |
| orbicular zone | Fibres of the articular capsule of the hip joint encircling the neck of the femur. Synonym: orbicular zone, ring ligament, zonular band. (05 Mar 2000) |
| ABC process | Purification of water or deodorization of sewage by a mixture of alum, blood, and charcoal. (05 Mar 2000) |
| accessory process | A small apophysis at the posterior part of the base of the transverse process of each of the lumbar vertebrae. Synonym: processus accessorius, accessory tubercle. (05 Mar 2000) |
| acromial process | <anatomy> The lateral triangular projection of the spine of the scapula that forms the point of the shoulder and articulates with the clavicle. (27 Sep 1997) |
| activated sludge process | <procedure> A method of treating sewage and wastewater through microbial oxidation. Sewage previously treated in settling tanks is aerated to encourage the growth of nonpathogenic aerobic microorganisms (bacteria, yeasts, moulds and protozoans) which break the organic matter down into carbon dioxide, water and simple salts. After this activated sludge is produced, the wastewater undergoes further processing through anaerobic digestion, filtering and chlorination. (29 Dec 1997) |
| adiabatic process | <chemistry> A process in which the system does not exchange heat with the surroundings. (15 Jan 1998) |
| agene process | Bleaching of flour with nitrogen trichloride (prohibited in the United States). (05 Mar 2000) |