| margin of fossa ovalis | A muscular ring surrounding the fossa ovalis in the wall of the right atrium of the heart. Synonym: annulus ovalis, margin of fossa ovalis, Vieussens' annulus, Vieussens' isthmus, Vieussens' limbus, Vieussens' ring. (05 Mar 2000) |
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| margin of orbit | The mostly sharp edge of the orbital opening which is the peripheral border of the base of the pyramid-shaped orbit. The superior half of the orbital rim is the supraorbital margin; the inferior half is the infraorbital margin. The frontal, maxillary, and zygomatic bones contribute to the orbital rim, which is generally strong to protect the orbital contents. Weak, potential fracture sites of the rim coincide with the sutures between the participating bones. Synonym: margin of orbit. (05 Mar 2000) |
| margin of safety | The margin between the minimal therapeutic dose and the minimal toxic dose of a drug. (05 Mar 2000) |
| margin of the tongue | The lateral border that separates the dorsum from the inferior surface of the tongue on each side, the two borders meeting anteriorly at the apex. Synonym: margo linguae. (05 Mar 2000) |
| parietal margin | Edge of a bone which articulates with the parietal bone. See: parietal border of frontal bone, parietal border of sphenoid bone, parietal border of temporal bone. Synonym: margo parietalis, parietal margin. (05 Mar 2000) |
| mastoid margin of occipital bone | The margin of the occipital squama that articulates with the temporal bone. Synonym: margo mastoideus squamae occipitalis, mastoid margin of occipital bone. (05 Mar 2000) |
| gingival margin | The most coronal portion of the gingiva surrounding the tooth, the edge of the free gingiva. Synonym: cervical margin, gingival crest. (05 Mar 2000) |
| cavity margin | The periphery of a filling, the line of junction between a restoration and the external surface of a tooth. (05 Mar 2000) |
| medial margin | The border of a structure closest to the medial plane. Synonym: margo medialis, medial margin. (05 Mar 2000) |
| reserve margin | The amount by which the utility's total electric power capacity exceeds maximum electric demand. (05 Dec 1998) |
| cervical margin | Termination of a restoration in the gingival area. (05 Mar 2000) |
| cervical margin of tooth | The slightly constricted part of a tooth, between the crown and the root. Synonym: cervix dentis, cervical margin of tooth, cervical zone of tooth, collum dentis, dental neck. (05 Mar 2000) |
| mesovarian margin of ovary | The border of the ovary to which the mesovarium is attached. Synonym: margo mesovaricus ovarii, mesovarian margin of ovary. (05 Mar 2000) |
| right margin of heart | The border between the sternocostal and diaphragmatic surfaces of the heart; it is fairly well defined in fixed hearts but is rounded and indefinite in the living heart. Synonym: margo dexter cordis, right margin of heart. (05 Mar 2000) |
| ciliary margin of iris | The peripheral border of the iris attached to the ciliary body. Synonym: margo ciliaris iridis, ciliary margin of iris. (05 Mar 2000) |