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.
- superciliary r. SYN: superciliary arch.
- supraorbital r. SYN: supraorbital margin.
- 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].
- triangular r. [TA] SYN: crista triangularis.
- 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..
- wolffian r. SYN: urogenital r..
* * *
a) the projecting or elevated part of the back along the line of the backbone
b) an elevated body part projecting from a surface
* * *
n.
* * *
(rij) a projection or projecting structure; see also carina, crest, and crista.Medical dictionary. 2011.