- 1. A mark seemingly made by pressure of one structure or organ on another, seen especially in cadaveric dissections. See also groove for the various impressions of the lungs, e.g., descending aorta, subclavian artery, and vena cavae. 2. An effect produced upon the mind by some external object acting through the organs of sense. SYN: mental i.. 3. An imprint or negative likeness; especially, the negative form of the teeth and/or other tissues of the oral cavity, made in a plastic material that becomes relatively hard or set while in contact with these tissues, made in order to reproduce a positive form or cast of the recorded tissues; classified, according to the materials of that they are made, as reversible and irreversible hydrocolloid i., modeling plastic i., plaster i., and wax i.. SYN: impressio [TA]. [L. impressio, fr. im- primo, pp. -pressus, to press upon]- aortic i. of left lung a broad deep groove on the medial aspect of the left lung above and behind the hilum receiving the arch of the aorta and the thoracic aorta. SYN: aortic sulcus, impressio aortica pulmonis sinistri, sulcus aorticus.- basilar i. an invagination of the base of the skull into the posterior fossa with compression of the brainstem and cerebellar structures into the foramen magnum. Cf.:platybasia.- cardiac i. of diaphragmatic surface of liver [TA] a depression on the superior area of the diaphragmatic surface of the liver corresponding to the position of the heart. SYN: impressio cardiaca faciei diaphragmaticae hepatis [TA].- cardiac i. on lung [TA] the depression on the medial surface of each lung produced by the presence of the heart. It is more pronounced on the left lung. SYN: impressio cardiaca pulmonis.- impressions of cerebral gyri [TA] the depressions on the inner surface of the skull which correspond to the convolutions of the brain. SYN: impressiones gyrorum [TA], impressiones digitatae, juga cerebralia, digitate impressions.- colic i. on liver [TA] a hollow on the visceral surface of the right lobe of the liver anteriorly, corresponding to the situation of the right flexure and beginning of the transverse colon. SYN: impressio colica hepatis [TA].- colic i. of spleen [TA] the part of the visceral surface of the spleen in contact with the colon. SYN: facies colica splenis [TA], colic surface of spleen.- complete denture i. 1. an i. of an edentulous arch made for the purpose of constructing a complete denture; 2. a negative registration of the entire denture-bearing, stabilizing area of either the maxillae or mandible; 3. a negative registration of the entire denture foundation and border seal areas present in the edentulous mouth.- i. for costoclavicular ligament [TA] an irregular pitted area on the inferior surface of the clavicle at its sternal end, giving attachment to the costoclavicular ligament. SYN: impressio ligamenti costoclavicularis [TA], costal tuberosity, rhomboid i., tuberositas costalis.- duodenal i. on liver [TA] a hollow on the visceral surface of the right lobe of the liver alongside the gallbladder, marking the situation of the duodenum. SYN: impressio duodenalis hepatis [TA].- esophageal i. on liver [TA] the marking of the esophagus on the back of the left lobe of the liver. SYN: impressio esophagea hepatis [TA].- gastric i. on liver [TA] a hollow on the visceral surface of the left lobe of the liver corresponding to the location of the stomach. SYN: impressio gastrica hepatis [TA].- gastric i. on spleen [TA] the surface of the spleen in contact with the stomach. SYN: facies gastrica splenis [TA], gastric surface of spleen.- partial denture i. an i. or negative copy of all or a part of the partially edentulous dental arch or area, made for the purpose of designing or constructing a partial denture.- petrosal i. of the pallium a shallow i. on the inferior surface of the cerebral hemisphere made by the superior margin of the petrous part of the temporal bone. SYN: impressio petrosa pallii.- preliminary i. in dentistry, one made for the purpose of diagnosis or the construction of a tray. SYN: primary i..- renal i. on liver [TA] a hollow on the visceral surface of the right lobe of the liver, in which lies the right kidney. SYN: impressio renalis hepatis [TA].- renal i. of spleen [TA] the portion of the visceral surface of the spleen that contacts the left kidney. SYN: facies renalis splenis [TA], facies renalis lienis, renal surface of spleen.- sectional i. an i. that is made in sections.- suprarenal i. on liver [TA] a hollow on the visceral surface of the right lobe of the liver, adjoining the groove for inferior venae cava, in which lies the right suprarenal gland. SYN: impressio suprarenalis hepatis [TA].- trigeminal i. [TA] a depression on the anterior surface of the petrous portion of the temporal bone, near the apex, formed in relationship to the trigeminal ganglion. SYN: impressio trigeminalis [TA].
* * *im·pres·sion im-'presh-ən n1) an imprint in plastic material of the surfaces of the teeth and adjacent portions of the jaw from which a likeness may be produced in dentistry2) an esp. marked influence or effect on the senses or the mind
* * *n.(in dentistry) a mould made of the teeth and surrounding soft tissues or of a toothless jaw. A soft impression material (e.g. silicone or alginate) is placed over the teeth or jaw and sets within several minutes, producing an elastic mould. Impressions may also be taken with hard-setting materials (e.g. plaster or zinc oxide-eugenol cement). After removal from the mouth a plaster model is made; on this are constructed restoration of teeth, denture, or orthodontic appliance.
* * *im·pres·sion (im-preshґən) [L. impressio] 1. a slight indentation or depression; see impressio. 2. a negative copy or the impressed reverse of the surface of an object. 3. an effect produced upon the mind, body, or senses by some external stimulus or agent. 4. dental i.
Medical dictionary. 2011.