- 1. A (usually rough) linear elevation. SEE ALSO: crest. 2. In dentistry, any linear elevation on the surface of a tooth. 3. The remainder of the alveolar process and its soft tissue covering after the teeth are removed. [A. S. hyrcg, back, spine]- apical ectodermal r. the layer of surface ectodermal cells at the apex of the embryonic limb bud; thought to exert an inductive influence on the condensation of underlying mesenchyme and be necessary for continued outgrowth of the limb.- buccogingival r. a distinct r. on the buccal surface of a deciduous molar tooth, approximately 1.5 mm from the crown-root junction.- bulbar r. one of two spiral subendocardial thickenings in the embryonic bulbus cordis; when they fuse, they divide the bulbus into the aorta and pulmonary artery.- bulboventricular r. an elevation on the inner surface of the embryonic heart at 4–5 weeks; it indicates the division between the developing ventricles and the bulbus cordis.- dermal ridges [TA] surface ridges of the epidermis of the palms and soles, where the sweat pores open. SYN: cristae cutis [TA], epidermal ridges, papillary ridges, skin ridges.- epidermal ridges SYN: dermal ridges.- epipericardial r. an elevation separating the developing pharyngeal region from the embryonic pericardium.- gonadal r. an elevation of thickened mesothelium and underlying mesenchyme on the ventromedial border of the embryonic mesonephros; the primordial germ cells become embedded in it, establishing it as the primordium of the testis or ovary. SYN: genital r..- interpapillary ridges SYN: rete r..- key r. SYN: zygomaxillare.- lateral supraepicondylar r. [TA] the distal sharp portion of the lateral margin of the humerus. SYN: crista supraepicondylaris lateralis [TA], crista supracondylaris lateralis, lateral supracondylar r., lateral epicondylar crest, lateral epicondylar r., lateral supracondylar crest.- linguocervical r. SYN: linguogingival r..- linguogingival r. a r. occurring on the lingual surface, near the cervix, of the incisor and cuspid teeth. SYN: linguocervical r..- mammary r. bandlike thickening of ectoderm in the embryo extending on either side from just below the axilla to the inguinal region; in human embryos, the mammary glands arise from primordia in the thoracic part of the r., the balance of the r. disappearing; in some lower mammals that give birth to a litter of young, several milk glands develop along these lines. SYN: mammary fold, milk line, milk r..- medial supraepicondylar r. [TA] the distal sharp portion of the medial margin of the humerus. SYN: crista supraepicondylaris medialis [TA], crista supracondylaris medialis, medial supracondylar r., medial epicondylar crest, medial epicondylar r., medial supracondylar crest.- mesonephric r. a r. that, in early human embryos, composes the entire urogenital r.; however, later in development a more medial genital r., the potential gonad, is demarcated from it. SEE ALSO: urogenital r.. SYN: mesonephric fold.- nasal r. SYN: agger nasi.- oblique r. a r. on the masticatory surface of an upper molar tooth from the mesiolingual to the distobuccal cusp.- papillary ridges SYN: dermal ridges.- Passavant r. a prominence on the posterior wall of the nasopharynx formed by contraction of the superior constrictor muscle of the pharynx during swallowing. SYN: Passavant bar, Passavant cushion, Passavant pad.- pronator r. an oblique r. on the anterior surface of the ulna, giving attachment to the pronator quadratus muscle.- pulmonary ridges a pair of ridges overlying the common cardinal veins and bulging from the lateral body wall into the embryonic celom; so called because they give early indication of where the pleuropericardial folds will develop.- residual r. that portion of the processus alveolaris remaining in the edentulous mouth following resorption of the section containing the alveoli.- rete r. downward thickening of the epidermis between the dermal papillae; peg is a misnomer because the dermal papillae are cylindric but the epidermal thickening between papillae is not. SYN: interpapillary ridges, rete pegs.- sphenoidal ridges sharp posterior margins of the lesser wings of the sphenoid bone that end medially in the anterior clinoid process; the sphenoidal ridges demarcate the anterior cranial fossa from the lateral part of the middle cranial fossa.- temporal r. SYN: inferior temporal line of parietal bone, superior temporal line of parietal bone.- transverse ridges of sacrum [TA] one of four ridges that cross the pelvic surface of the sacrum; these mark the positions of the intervertebral disks between the bodies of the five sacral vertebrae in the immature bone. SYN: lineae transversae ossis sacri [TA].- urogenital r. one of the paired longitudinal ridges developing in the dorsal body wall of the embryo on either side of the dorsal mesentery; the r. is formed at first by the growing mesonephros and later by the mesonephros and the gonad. SYN: genital fold, wolffian r..
* * *a) the projecting or elevated part of the back along the line of the backboneb) an elevated body part projecting from a surface
* * *n.
* * *(rij) a projection or projecting structure; see also carina, crest, and crista.
Medical dictionary. 2011.