| superior nuchal line | The ridge that extends laterally from the external occipital protuberance toward the lateral angle of the occipital bone; it gives attachment to the trapezius, sternocleidomastoid, and splenius capitis muscles. Synonym: linea nuchae superior. (05 Mar 2000) |
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| superior temporal line | The upper of two curved lines on the parietal bone; the temporal fascia is attached to it. Synonym: linea temporalis superior, temporal ridge. (05 Mar 2000) |
| supracrestal line | A transverse line transecting the high point of both iliac crests, indicating the supracristal plane. See: supracristal plane. Synonym: linea supracristalis. (05 Mar 2000) |
| survey line | A line scribed on an abutment tooth of a dental cast by means of a dental surveyor indicating the height of contour of the tooth according to a specific path of insertion, a line which serves as a guide in the proper location of various parts of a clasp assembly for a removable partial denture. Synonym: clasp guideline, Cummer's guideline. (05 Mar 2000) |
| demarcation line of retina | Junction of avascular and vascular retina in retinopathy of prematurity; line marking the limits of an old retinal detachment. (05 Mar 2000) |
| Dennie's line | An accentuated line or fold below the margin of the lower eyelid; characteristic in atopic dermatitis. Synonym: Dennie's infraorbital fold. (05 Mar 2000) |
| Sydney line | A variation of the proximal transverse palmar flexion crease that reaches the ulnar side of the palm; associated with acute lymphocytic anaemia in early childhood, rubella embryopathy, and Down's syndrome. Synonym: Sydney line. (05 Mar 2000) |
| sylvian line | The line of the posterior limb of the lateral sulcus (sylvian fissure) of the cerebral cortex. (05 Mar 2000) |
| dentate line | The line between the simple columnar epithelium of the rectum and the stratified epithelium of the anal canal. Synonym: linea anocutanea, anocutaneous line, dentate line. (05 Mar 2000) |
| Douglas' line | A crescentic line, not always clearly defined, which marks the lower limit of the posterior layer of the sheath of the rectus abdominis muscle. Synonym: linea arcuata vaginae musculi recti abdominis, Douglas' line, linea saemicircularis, saemicircular line. (05 Mar 2000) |
| drift line | An accumulation of water-carried debris along a contour or at the base of vegetation that provides direct evidence of prior inundation and often indicates the directional flow of flood waters. (09 Oct 1997) |
| iliopectineal line | An oblique ridge on the inner surface of the ilium and continued on the pubis, which forms the lower boundary of the iliac fossa; it separates the true from the false pelvis. Synonym: iliopectineal line, terminal line. (05 Mar 2000) |
| inferior nuchal line | A ridge that extends laterally from the external occipital crest toward the jugular process of the occipital bone. Synonym: linea nuchae inferior. (05 Mar 2000) |
| inferior temporal line | The lower of two curved lines on the parietal bone; it marks the outer limit of attachment of the temporalis muscle. Synonym: linea temporalis inferior, temporal ridge. (05 Mar 2000) |
| infracostal line | A horizontal plane passing through the inferior limits of the costal margin, i.e., the tenth costal cartilages; it marks the boundary between the hypochondriac and epigastric regions superiorly and the lateral and umbilical regions inferiorly. Synonym: planum subcostale, infracostal line. (05 Mar 2000) |