| frontal suture | The suture between the two halves of the frontal bone, usually obliterated by about the sixth year; if persistent it is called a metropic suture. Synonym: sutura frontalis. (05 Mar 2000) |
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| frontal triangle | A triangle bounded above by the maximum frontal diameter and laterally by lines joining the extremities of this diameter with the glabella. (05 Mar 2000) |
| frontal tuber | The most prominent portion of the frontal bone on either side. Synonym: tuber frontale, eminentia frontalis, frontal tuber. (05 Mar 2000) |
| frontal veins | The superficial veins draining the frontal cortex and emptying into the superior sagittal sinus. Synonym: supratrochlear veins. (05 Mar 2000) |
| frontal zone contraction theory | Model proposed to account for the movement of giant amoebae in which cytoplasmic contraction at the front of the leading pseudopod (fountain zone) pulls viscoelastic cytoplasm forward in the centre of the cell and forms a tube of more rigid cytoplasm immediately below the plasma membrane behind the active region. The peripheral contracted cytoplasm relaxes into a weaker gel at the rear and is pulled forward in its turn. Contrasts with the ectoplasmic tube contraction model. (18 Nov 1997) |
| alveolar border | The most occlusal edge of the alveolar bone. Synonym: alveolar process. (05 Mar 2000) |
| anterior border | The ventral or most forward margin of a structure. Synonym: anterior margin, ventral border. (05 Mar 2000) |
| anterior border of eyelids | The anterior edge of the free margin of each eyelid, along close to which the eyelashes are embedded. Synonym: limbus palpebrales anteriores. (05 Mar 2000) |
| anterior border of fibula | A ridge on the shaft of the fibula to which is attached the anterior intermuscular septum of the leg. Synonym: margo anterior fibulae. (05 Mar 2000) |
| anterior border of lung | The thin anteromedial or sternal edge of the lung which overlaps the pericardial sac anteriorly and forms the boundary between the mediastinal and costal surfaces. Synonym: margo anterior pulmonis. (05 Mar 2000) |
| anterior border of pancreas | The sharp margin between the anterior and inferior surfaces of the pancreas. Synonym: margo anterior pancreatis. (05 Mar 2000) |
| anterior border of radius | The ridge on the shaft of the radius extending from the radial tuberosity to the anterior part of the styloid process. Synonym: margo anterior radii. (05 Mar 2000) |
| anterior border of testis | An imaginary convex line demarcating the lateral and medial surfaces. Synonym: margo anterior testis. (05 Mar 2000) |
| anterior border of tibia | The sharp subcutaneous ridge of the tibia that extends from the tuberosity to the anterior part of the medial malleolus. Synonym: margo anterior tibiae, anticnemion, shin, tibial crest. (05 Mar 2000) |
| anterior border of ulna | The ridge on the body of the ulna that extends from the tuberosity to the anterior part of the styloid process. Synonym: margo anterior ulnae. (05 Mar 2000) |