1. a stripe, streak, mark, or narrow ridge; often an imaginary line connecting different landmarks. See also linea.
2. conversion of a broad beam of x-rays to a pencil beam.
3. a single consignment of livestock from one farm. Said of a group of cattle or sheep notable for their homogeneity.
- absorption l's — dark lines in the spectrum due to absorption of light by the substance through which the light has passed.
- l. block — a nerve block of local anesthesia produced by infiltrating the anesthetic along a line that the incision is to take.
- blue l. — lead line (below).
- cell l. — see cell culture.
- cement l. — a line visible in microscopic examination of bone in cross section, marking the boundary of an osteon (haversian system).
- cervical l. — see cemento-enamel junction.
- cleavage l's — linear clefts in the skin indicative of direction of the fibers.
- l. dressing — a system of handling carcasses in an abattoir. The carcasses move along an overhead chain line past a series of stations where the dressing and meat inspection is done.
- l. focus — utilization of a broad beam of electrons for the generation of x-rays by a rotating anode so that the area of the target on which the electrons fall is spread over a line instead of a point.
- gingival l. — 1. a line determined by the level to which the gingiva extends on a tooth; called also gum line. — 2. any linear mark visible on the surface of the gingiva.
- gum l. — gingival line (1).
- iliopectineal l. — the ridge on the ilium and pubes showing the brim of the true pelvis.
- incremental l's — lines supposedly showing the successive layers deposited in a tissue, as in the tooth enamel.
- intertrochanteric l. — one running obliquely from the greater to the lesser trochanter.
- lead l. — a bluish line at the edge of the gums in lead poisoning. Rarely seen in animals.
- median l. — an imaginary vertical line dividing the body equally into right and left parts.
- milk l. — 1. the line of thickened epithelium in the embryo along which the mammary glands are developed. — 2. the metal tube in a milking machine along which the milk, after extraction from the cow, passes to the storage vat.
- mylohyoid l. — a ridge on the inner surface of the lower jaw from the base of the symphysis to the ascending rami behind the last molar tooth.
- pectinate l. — one marking the junction of the zone of the anal canal lined with stratified squamous epithelium and the zone lined with columnar epithelium.
- physeal l. — one on the surface of an adult long bone, marking the junction of the epiphysis and diaphysis.
- pleural reflection l. — line of the junction between costal and diaphragmatic pleurae.
- semilunar l. — a curved line along the lateral border of each rectus abdominis muscle, marking the meeting of the aponeuroses of the internal oblique and transverse abdominal muscles.
- temporal l. — a curved ridge on the external surface of the cranium that marks the origin of the temporal muscle.
- terminal l. — one on the inner surface of each pelvic bone, from the sacroiliac joint to the iliopubic eminence cranially, separating the false from the true pelvis, and marking the pelvic inlet.
- l. transects — a technique for estimating the density of a population, e.g. the number of deer per hectare in a gamepark.
- visual l. — a line from the point of vision of the retina to the object of vision; called also visual axis.
