| lower lip | The muscular fold bounding the opening of the mouth inferiorly. Synonym: labium inferius oris. (05 Mar 2000) |
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| low lip line | The lowest position of the lower lip during the act of smiling or voluntary retraction, the lowest position of the upper lip at rest. (05 Mar 2000) |
| alveolobuccal sulcus | The upper and lower half of the buccal vestibule on each side. Synonym: alveolobuccal sulcus, gingivobuccal groove, gingivobuccal sulcus. (05 Mar 2000) |
| alveololabial sulcus | The upper and lower half of the labial vestibule, in the embryo, the groove formed by the deepening of the labial sulcus; its inner wall becomes incorporated with the alveolar process of the mandible or the maxilla, and its outer wall with the lips and cheeks. Synonym: alveololabial sulcus, gingivolabial groove, gingivolabial sulcus. (05 Mar 2000) |
| alveololingual sulcus | That part of the oral cavity proper, on each side of the frenulum linguae, between the tongue and the mandibular alveolar process or ridge, in the embryo, the groove on each side between the lingual primordium and the alveolar elevations of the mandible. Synonym: alveololingual sulcus, gingivolingual groove, gingivolingual sulcus. (05 Mar 2000) |
| ampullary sulcus | The groove on the external surface of the ampulla of each saemicircular duct where the nerve enters the crista ampullaris. Synonym: sulcus ampullaris. (05 Mar 2000) |
| anterior intermediate sulcus | A furrow occasionally seen in the adult between the anterior median fissure and the anterior lateral sulcus of the spinal cord but usually present only in the foetus. It indicates the lateral border of the anterior corticospinal fasciculus. Synonym: anterior intermediate groove, sulcus intermedius anterior. (05 Mar 2000) |
| anterior parolfactory sulcus | A fissure marking the anterior border of the parolfactory area. Synonym: sulcus parolfactorius anterior. (05 Mar 2000) |
| anterolateral sulcus | An indistinct furrow on the ventral surface of the spinal cord and medulla oblongata, on either side marking the line of exit of the anterior nerve roots. Synonym: sulcus lateralis anterior, anterolateral groove. (05 Mar 2000) |
| aortic sulcus | 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. Synonym: sulcus aorticus. (05 Mar 2000) |
| artery of central sulcus | <anatomy, artery> A branch of the terminal part of the middle cerebral artery distributed to the cortex on either side of the central sulcus. Synonym: arteria sulci centralis, artery of central sulcus, central artery, Rolandic artery. (05 Mar 2000) |
| artery of postcentral sulcus | <anatomy, artery> A branch of the terminal part of the middle cerebral artery distributing to the cortex on either side of the postcentral sulcus. Synonym: arteria sulci postcentralis, artery of postcentral sulcus, postcentral artery. (05 Mar 2000) |
| artery of precentral sulcus | <anatomy, artery> A branch of the terminal part of the middle cerebral artery distributed to the cortex on either side of the precentral sulcus. Synonym: arteria sulci precentralis, artery of precentral sulcus, pre-Rolandic artery, precentral artery. (05 Mar 2000) |
| atrioventricular sulcus | A groove on the outer surface of the heart marking the division between the atria and the ventricles. Synonym: sulcus coronarius, atrioventricular groove, atrioventricular sulcus, auriculoventricular groove, coronary sulcus. (05 Mar 2000) |
| basilar pontine sulcus | A median groove on the ventral surface of the pons varolii in which lies the basilar artery. Synonym: sulcus basilaris pontis, basilar sulcus. (05 Mar 2000) |