| OPLL | ossification of posterior longitudinal ligament |
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| PLL | peripheral light loss; phase-locked loop; poly-L-lysine; pressure length loop; posterior longitudina... |
| riMLF | rostral interstitial median longitudinal fasciculus |
| T1 | longitudinal relaxation time |
| T1 | spin-lattice or longitudinal relaxation time; tricuspid first sound |
| longitudinal lie | That relationship in which the long axis of the foetus is longitudinal and roughly parallel to the long axis of the mother; the presenting part may be either the head or the breech. (05 Mar 2000) |
|---|---|
| longitudinal ligament | <anatomy> One of two extensive fibrous bands running the length of the vertebral column: the anterior longitudinal ligament and the posterior longitudinal ligament. Synonym: ligamentum longitudinale. (05 Mar 2000) |
| longitudinal ligaments | Two extensive fibrous bands running the length of the vertebral column. The anterior longitudinal ligament (ligamentum longitudinale anterius; lacertus medius) interconnects the anterior surfaces of the vertebral bodies; the posterior longitudinal ligament (ligamentum longitudinale posterius) interconnects the posterior surfaces. The commonest clinical consideration is ossification of posterior longitudinal ligament. (12 Dec 1998) |
| longitudinal magnification | <microscopy> A certain distance, measured axially, in the object space as referred to the respective distance in the image space. The ratio of the distance D' in the image space to the distance D in the object space equated to the square of the linear magnification M of the system. Thus: M exp2 =D'/D. (05 Aug 1998) |
| longitudinal method | In developmental psychology, the study of the life span of one individual involving comparisons of different age levels. Compare: cross-sectional method. (05 Mar 2000) |
| longitudinal oval pelvis | A pelvis in which the anteroposterior diameter is longer than the transverse. Synonym: longitudinal oval pelvis. (05 Mar 2000) |
| longitudinal pontine bundles | The massive bundles of corticofugal fibres passing longitudinally through the ventral part of pons; they are composed of corticopontine, corticobulbar, and corticospinal fibres. Synonym: fasciculi longitudinales pontis, longitudinal pontine bundles. (05 Mar 2000) |
| longitudinal pontine fasciculi | The massive bundles of corticofugal fibres passing longitudinally through the ventral part of pons; they are composed of corticopontine, corticobulbar, and corticospinal fibres. Synonym: fasciculi longitudinales pontis, longitudinal pontine bundles. (05 Mar 2000) |
| longitudinal relaxation | In nuclear magnetic resonance, the return of the magnetic dipoles of the hydrogen nuclei (magnetization vector) to equilibrium parallel to the magnetic field, after they have been flipped 90 |
| longitudinal section | A section that is cut along the long axis of a structure. The opposite is a cross-section. (12 Dec 1998) |
| longitudinal sinus | See: inferior sagittal sinus, superior sagittal sinus. Longitudinal vertebral venous sinus, large, plexiform veins forming portions of the anterior internal vertebral venous plexus lying on the posterior surfaces of the vertebral bodies on either side of the posterior longitudinal ligament. Synonym: sinus vertebrales longitudinales. Luschka's sinus, venous sinus in the petrosquamous suture. (05 Mar 2000) |
| longitudinal studies | Studies in which variables relating to an individual or group of individuals are assessed over a period of time. (12 Dec 1998) |
| longitudinal study | <epidemiology> A study taking place over time. If individuals are followed, this is a longitudinal cohort study. If individuals are not followed, but classes (usually age classes) are restudied, this is a longitudinal cross-sectional study. The converse of a horizontal study. (05 Dec 1998) |
| longitudinal sulcus of heart | See: anterior interventricular groove, posterior interventricular groove. (05 Mar 2000) |
| longitudinal wave | <physics> Waves where the variation of the field is partially or totally in the direction of propagation (parallel to wavennumber, k [a vector]). Examples include sound waves and Langmuir waves. Contrasted with transverse waves, where the variation is perpendicular to the direction of propagation, such as light waves. (13 Nov 1997) |