Dictionary

lockjaw See tetanus.

locomotion 1 Movement from one place to another. 2 The ability to get from one place to the next. See also locomotive system.

locomotive system The bones, the joints, and the muscles that contract and relax to move the joints and bones.

locus In genetics, the place a gene occupies on a chromosome. The plural is loci.

Loeys-Dietz syndrome An inherited syndrome characterized by aortic aneurysms and other blood vessel abnormalities in children. The condition is often associated with other birth defects. The aortic aneurysms of Loeys-Dietz syndrome are prone to rupture at a smaller size than other aneurysms, with early identification of the condition and surgical intervention critical for survival.

loin The portion of the lower back from just below the ribs to the pelvis.

long QT syndrome A disorder of the heart’s electrical system that predisposes individuals to irregular heartbeats, fainting spells, and sudden death. The irregular heartbeats are typically brought on by stress or vigorous activity. Abbreviated LQTS. LQTS is often symptomless and undiagnosed, but it is well known as a cause of sudden cardiac death in young,…

long-chain-3-hydroxyacyl-CoA dehydrogenease deficiency See deficiency, LCHAD.

longevity Lifespan. Increased longevity means a longer life.

longitudinal Along the length of something; running lengthwise or, by extension, over the course of time.

longitudinal section A section that is cut along the long axis of a structure. Longitudinal section is the opposite of cross-section.

longitudinal study A study done over the passage of time. For example, a longitudinal study of children with Down syndrome might involve the study of 100 children with this condition from birth to 10 years of age. Longitudinal study is the opposite of cross-sectional (synchronic) study. Also known as diachronic study.