| atlas | 1. One who sustains a great burden. 2. <anatomy> The first vertebra of the neck, articulating immediately with the skull, thus sustaining the globe of the head, whence the name. 3. A collection of maps in a volume. Supposed to be so called from a picture of Atlas supporting the world, prefixed to some collections. This name is said to have been first used by Mercator, the celebrated geographer, in the 16th century. 4. <chemistry> Atlas powder, a nitroglycerin blasting compound of pasty consistency and great explosive power. Origin: L. Atlas, -antis, Gr, one of the older family of gods, who bears up the pillars of heaven; also Mt. Atlas, in W. Africa, regarded as the pillar of heaven. It is from the root of to bear. See Tolerate. Source: Websters Dictionary (01 Mar 1998) |
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| atlas fracture | <radiology> Incidence: 4% of cervical spine injuries, site: posterior arch, anterior arch, massa lateralis, Jefferson fracture associated with: fractures of C7 (25%), fractures of C2 pedicle (15%), extraspinal fractures (58%) (12 Dec 1998) |
| posterior arch of atlas | The posterior arch of the atlas that connects the lateral masses of the atlas posteriorly, forming the posterior wall of the vertebral canal at this level. Synonym: arcus posterior atlantis. (05 Mar 2000) |
| cruciate ligament of the atlas | The strong ligament that lies posterior to the dens of the axis holding it against the anterior arch of the atlas; it consists primarily of the transverse ligament of the atlas that forms the cross-bar of the cross and is most important functionally, and longitudinal bands of the cruciform ligament, forming the upright or vertical beams of the cross. Synonym: ligamentum cruciforme atlantis, crucial ligament, cruciate ligament of the atlas, ligamentum cruciatum atlantis. (05 Mar 2000) |
| cruciform ligament of atlas | The strong ligament that lies posterior to the dens of the axis holding it against the anterior arch of the atlas; it consists primarily of the transverse ligament of the atlas that forms the cross-bar of the cross and is most important functionally, and longitudinal bands of the cruciform ligament, forming the upright or vertical beams of the cross. Synonym: ligamentum cruciforme atlantis, crucial ligament, cruciate ligament of the atlas, ligamentum cruciatum atlantis. (05 Mar 2000) |
| posterior tubercle of atlas | A protuberance of the posterior extremity of the arch of the atlas, a rudiment of the spinous process giving attachment to the musculus rectus capitis posterior minor muscle. Synonym: tuberculum posterius atlantis. (05 Mar 2000) |
| superior articular pit of atlas | One of two concave articular surfaces on the superior aspect of the lateral masses of the atlas that articulate with the occipital condyles. Synonym: facies articularis superior atlantis, fovea articularis superior atlantis, superior articular pit of atlas. (05 Mar 2000) |
| inferior articular pit of atlas | One of two concave surfaces on the lateral masses of the atlas that articulate with corresponding surfaces on the axis. Synonym: facies articularis inferior atlantis, fovea articularis inferior atlantis, inferior articular pit of atlas. (05 Mar 2000) |
| transverse ligament of the atlas | Thick, strong, centrally flattened band spanning the vertebral foramen of the atlas as it extends from the medial aspect of one lateral mass to the other, passing dorsal to the dens with which it articulates; it forms the dorsal portion of the opening for the dens, tightly embracing its neck. It forms a part of the "cross-bar" of the cruciform ligament of the atlas. See: cruciform ligament of atlas. Synonym: ligamentum transversum atlantis, Lauth's ligament, transverse atlantal ligament. (05 Mar 2000) |
| lateral mass of atlas | The thick lateral part of the atlas on each side that articulates above with the occipital condyle and below with the axis. Synonym: massa lateralis atlantis. (05 Mar 2000) |
| apex of dens | The tip of the dens of the axis to which is attached the apical ligament of the dens. Synonym: apex dentis. (05 Mar 2000) |
| apical ligament of dens | A ligament that extends from the apex of the dens of the axis to the anterior margin of the foramen magnum; includes vestiges of notochord. Synonym: ligamentum apicis dentis. (05 Mar 2000) |
| posterior articular surface of dens | The facet on the posterior surface of the dens of the axis that articulates with the transverse ligament of the atlas. Synonym: facies articularis posterior dentis. (05 Mar 2000) |
| dens | Synonym: Tooth. 2. A strong toothlike process projecting upward from the body of the axis, or epistropheus, around which the atlas rotates. Synonym: odontoid process of epistropheus, odontoid process. Origin: L. (05 Mar 2000) |
| dens angularis | <dentistry> A tooth having a crown of thick conical shape and a long, slightly flattened conical root; there are two canine teeth in each jaw, one on either side adjacent to the distal surface of the lateral incisors, in both the deciduous and the permanent dentition. Synonym: dens caninus, canine, cuspid tooth, cuspidate tooth, cuspid, dens angularis, dens cuspidatus, eye tooth. (05 Mar 2000) |