Webster's New World Medical Dictionary

part of food digestion, although Lactobacillus can
also contribute to cavities in the teeth if allowed to
remain too long within the mouth.
Lactobacillus acidophilus
See 
acidophilus.
lactose intolerance
The inability to digest lac-
tose, a component of milk and some other dairy
products. The basis for lactose intolerance is the
lack of an enzyme called lactase in the small intes-
tine. The most common symptoms of lactose intol-
erance are diarrhea, bloating, and gas. The
diagnosis may be made via a trial of a lactose-free
diet or by special testing. Treatment involves avoid-
ance of products that contain lactose or use of lac-
tase enzyme supplements before eating. See also
deficiency, lactase.
lacuna
A small pit, cavity, defect, or gap. For
example, a lacunar infarct in the brain is an area
where a stroke has left a tiny pit in the brain.
lamella
A thin leaf, plate, disk, or wafer, such as
in bone tissue.
lamina
Plates or layers. For example, the lamina
arcus vertebrae are plates of bone within each ver-
tebral body.
laminaria
A thin piece of sterile seaweed that can
be used to gradually dilate the cervix.
laminectomy
A surgical procedure in which the
posterior arch of a vertebra is removed.
Laminectomy is done to relieve pressure on the
spinal cord or on the nerve roots that emerge from
the spinal canal. The procedure may be used to
treat a slipped or herniated disc or to treat spinal
stenosis.
lancet
A small, pointed knife that is used to prick
a finger for a blood test.
Lancet, The
A well-known medical journal pub-
lished in England. Founded in 1823, 
The Lancet
is
the longest-running medical journal in the world.