L - Glossary of Terms

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L - Glossary of Terms

labial	(la'be-al). Of or pertaining to lips, or labia.
labial frenulum	(la´be-al fren´yuu-lum) A longitudinal fold of mucous membrane that attaches the lips to the gum along the midline of both the upper and lower lip.
labia majora	(la´be-a mu-jor´ua), sing. labium majus A portion of the external genitalia of a female consisting of two longitudinal folds of skin extending downward and backward from the mons pubis.
labia minora	(mi-nor´a), sing. labium minus Two small folds of skin, devoid of hair and sweat glands, lying between the labia major of the external genitalia of a female.
labium	(la'bi-um) A lip; any lip-shaped part.
labyrinth	(lab´i-rinth) An intricate structure consisting of interconnecting passages (e.g., the bony and membranous labyrinths of the inner ear.
lacerated	(las'er-ated). Torn or mangled; not clean-cut; a wound inflicted by tearing.
lacrimal	(lak'ri-mal). Pertaining to or situated near lacrimal, or tear, gland; as lacrimal duct, lacrimal bone.
lacrimal canaliculus	(lak´ri-mal kan´´a-lik´yuu-lus) A drainage duct for tears, located at the medial corner of an eyelid. It conveys the tears medially into the nasolacrimal sac.
lacrimal gland	(A tear-secreting gland, located on the superior lateral portion of the eyeball underneath the upper eyelid.
lactation	(lak-ta´shun) The production and secretion of milk by the mammary glands.
lacteal	(lak´te-al) A small lymphatic duct associated with a villus of the small intestine.
lacuna	(la-koo´na) A small, hollow chamber that houses an osteocyte in mature bone tissue or a chondrocyte in cartilage tissue.
lag	Phosphorescence.
lambda	(lam'dah) Eleventh Greek letter; point of junction of lambdoidal and sagittal sutures of cranium, site of posterior fontanel.
lambdoidal suture	(lam´doid-al soo´chur) The immovable joint in the skull between the parietal bones and the occipital bone.
lamella	(la-mel´a) A concentric ring of matrix surrounding the central canal in an osteon of mature bone tissue.
lamellated corpuscle	(lam´e-la-ted) A sensory receptor for pressure, found in tendons, around joints, and in visceral organs; also called a pacinian corpuscle.
lamina	(lam´i-na) A thin plate of bone that extends superiorly from the body of a vertebra to form either side of the arch of a vertebra.
laminagraphy	(lami-nag'ra-fe). See tomography.
laminated	(lam'i-nated). Separated into or made up of thin, flat plates or layers; arranged in layers.
laminectomy	(lam"i-nek'to-me) Excision of posterior part of neural arch
laminography	See tomography.
lanugo	(la-noo´go) Short, silky fetal hair, which may be present for a short time on a premature infant.
laparo-	(lap'a-ro) Prefix signifying relation to flank, side of body extending between ribs and ilium or, more loosely, to abdominal wall; as laparotomy, surgical incision into abdominal wall.
large intestine	The last major portion of the GI tract, consisting of the cecum, colon, rectum, and anal canal.
laryngo-	(lar-in'go) Prefix denoting relation to larynx; as laryngotracheal laryngitis.
laryngogram	(Ia-rin'go-gram) Radiograph of larynx.
larynogography	(Iarin-gog-ra-fe). Radiographic examination of larynx with aid of contrast medium.
laryngopharynx	(la-ring´´go-far´ingks) The inferior or lower portion of the pharynx in contact with the larynx. 686
larynx	(lar´ingks) The structure located between the pharynx and trachea that houses the vocal cords; commonly called the voice box.
laser disk	A removable disk that uses laser technology to write and read data.
late effect	A radiation response that is not observed for 6 months or more after the exposure.
latent	(la'tent). Not apparent or manifest: dormant.
latent image	The information contained by the sensitised “specks” in the film emulsion where some of the silver ions in the silver halide crystal have been converted to neutral silver atoms by the action of the incident radiation. The information cannot be visualised at this stage and must be “developed” in order to provide a visible image.
latent image center	A sensitivity center that has many silver ions attracted to it.
latent period	The period after the prodromal stage of the acute radiation syndrome during which there is no visible sign of radiation sickness.
laterad	(later-ad). Directed toward side.
lateral	(lat´er-al) Pertaining to the side; farther from the midplane.
lateral decentering	The improper positioning of the grid that results in cutoff.
lateral ventricle	(ven´tri-k'l) A cavity within the cerebral hemisphere of the brain that is filled with cerebrospinal fluid.
latitude	The range of exposure levels to a film/screen combination that provides useful optical densities. The wider the range of useful exposures the higher the latitude. Film latitude and contrast are inversely related.
lavage	(lah"vahzh'). Washing out of an organ, especially irrigation of stomach.
law of Bergonie and Tribondeau	The principle stating that the radiosensitivity of cells is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation.
law of conservation of energy	The principle stating that energy may be transformed from one form to another but cannot be created or destroyed; the total amount of energy is constant.
law of conservation of matter	The principle stating that matter can be neither created nor destroyed.
law of inertia	The principle stating that a body will remain at rest or continue to move with a constant velocity in a straight line unless acted on by an external force.
laxative	(laks'a-tiv) Mild cathartic.
LD (50/60)	Dose of radiation expected to cause death within 60 days to 50% of those exposed.
leakage radiation	Secondary radiation emitted through the tube housing.
leg	(The portion of the lower extremity between the knee and ankle (see thigh)
lens	(lenz) A transparent refractive organ of the eye positioned posterior to the pupil and iris.
lesion	(le´zhun) A wounded or damaged area.
lesser omentum	(o-men´tum) A peritoneal fold of tissue extending from the lesser curvature of the stomach to the liver.
leukocytosis	Abnormal amount of white blood cells in the blood.
lien	(li'en). Latin for spleen.
lienal	(li-e'nal) Of or pertaining to spleen.
lienitis	(li"e-ne'tis) Inflammation of spleen.
lieno-	(Ii-e'no-) Prefix signifying relation to spleen; as lienorenal, pertaining to spleen and kidney.
lienography	(Li"en-og'ra-fe). Radiographic examination of spleen after injection of contrast medium.
ligament	(lig´a-ment) A tough cord or fibrous band of connective tissue that binds bone to bone to strengthen and provide flexibility to a joint. It also may support viscera.
ligamentous	(not to be confused with other uses of ligament) synonymous with omental, epiploic and mesenteric.
ligamentum flavum	connecting adjacent laminae. (see lamina, lumbar puncture
light localizer	A light source in most X-ray units to indicate the size and location of the primary beam.
limbic system	(lim´bik) A portion of the brain concerned with emotions and autonomic activity.
limbus	Latin = a margin, edge, usually curved
limiting resolution	The spatial frequency at a modulation transfer function equal to 0.1.
linea	(lin'e-ah) Latin for line; any normal strip, mark, or narrow ridge.
linea alba	(lin´e-a al´ba) A vertical fibrous band extending down the anterior medial portion of the abdominal wall.
linear energy transfer (LET)	A measure of the rate at which energy is transferred from ionising radiation to soft tissue. Expressed in kiloelectron volts per micrometer of soft tissue.
linear - nonthreshold	Referring to the dose-response relationship that intersects the dose axis at or below zero.
linear opacity	A shadow resembling a line; an elongated opacity of uniform width, qualified with regard to length, width, orientation, and anatomic location.
linear - threshold	Referring to the dose-response relationship that intercepts the dose axis at a value greater than zero.
linear tomography	The imaging modality in which the x-ray tube is mechanically attached to the image re¬ceptor and moves in one direction as the image receptor moves in the opposite direction.
line focus	The projection of an inclined line into a surface, resulting in a smaller size.
line focus principle	A design incorporated into X-ray tube targets to allow a large area for heating while maintaining a small focal spot.
linear grid	A grid in which the lead strips are all lined up in one direction. Linear grids may be focused or unfocused.
line pair	A unit of spatial resolution; defined as one opaque line and one adjacent space. A resolution of one line pair per millimeter means that lines ½ mm wide and ½ mm apart can be resolved. This measurement corresponds roughly to the maximum detected spatial frequency of the modulation transfer function.
lingua	(ling'gwah) Latin for tongue.
lingual	(ling-gwal) Of or pertaining to tongue; glossal.
lingual frenulum	(ling´gwal fren´yuu-lum) A longitudinal fold of mucous membrane that attaches the tongue to the floor of the oral cavity.
lipo-	(lip'o-) Prefix meaning fat, fatty: a, lipomyoma, a tumor composed of muscular and fatty elements.
lipoma	(Ii-po'mah) Tumor of fat.
-lith	(-lith) Suffix meaning a concretion or calculus; as phlebolith, a concretion or calculus in a vein.
lithiasis	(Ii-thi'a-sis) Formation of concretions or calculi in body, especially in urinary passages and gallbladder.
litho-	(lith'o-) Prefix meaning calculu' or concretion; as lithonephritis, inflammation of kidney caused by presence of calculi.
lithotomy position	(lith-ot'o-me) Position in which body is supine, legs flexed on thighs, and thighs flexed on abdomen and abducted; also called dorsosacral position (lying on the back, with the lower limbs elevated and the feet in stirrups).
liver	A large visceral organ inferior to the diaphragm in the right hypochondriac region. The liver detoxifies the blood and modifies the blood plasma concentration of glucose, triglycerides, ketone bodies, and proteins.
localize	(lo-kal-iz) To restrict or limit to one area or part.
localized	(lo'kal-izd) Restricted to a limited area; not general.
locular	(lok'u-lar) Divided into small cormpartments or loculi; pertaining to a loculus or loculi.
loculus	(lok'u-lus) Small cavity, compartment, or chamber; a recess or cell, as cells of ethmoidal sinuses.
lodestone	A leading stone.
logic function	A computer-recognised command that evaluates an intermediate result and performs subsequent computations depending on that result.
log relative exposure (LRE)	The change in optical density over each exposure interval.
loin	(loin) The portion of the body located between the ribs and crests of ilia and lateral to spine.
long gray scale	A low-contrast radiograph that has many shades of gray.
longitudinal	(lon"ji-tu'di-nal). Extending lengthwise, as distinguished from traverse; axial, as longitudinal plane of posterior teeth extends anteroposteriorly with long axis of mandible.
lordosis	(lor-do'sis) Curvature of spine with forward convexity.
low contrast resolution	The ability to image objects with similar subject contrast.
lower extremity	A lower appendage, including the hip, thigh, knee, leg, and foot.
lucency	he ability to transmit light, and thus the ability to transmit X-radiation.
lumbar	(lum´bar) Of or pertaining to the region of the loin: vertebrae situated in region of loin.
lumbar plexus	(plek´sus) A network of nerves formed by the anterior branches of spinal nerves L1 through L4.
lumbar puncture	insertion of hollow needle through the skin of the back, the ligamentum flavum, and the dura mater. In the Adult the needle should be inserted between the vertebtal laminae of L3/4. in a child one or two intervertebral spaces below. (see epidural)
lumbar region	A region of the abdomen (see hypochondriac, epigastric, umbilical, inguinal and hypogastric)
lumen	(loo´men) The space within a tubular structure through which a substance passes eg an artery, a bronchus, or intestine.
luminescence	The emission of visible light.
lung	One of the two major organs of respiration positioned within the thoracic cavity on either side of the mediastinum.
lunula	(loo´nyoo-la) The half-moon-shaped whitish area at the proximal portion of a nail.
luxation	(luks-a'shun). Act or condition of being dislocated or luxated; dislocation.
lymph	(limf) A clear, plasma like fluid that flows through lymphatic vessels.
lymph node	A small, ovoid mass of reticular tissue located along the course of lymph vessels.
lymphadenopathy	Any abnormality of lymph nodes, usually restricted to enlargement.
lymphangitic	Spread by means of the lymphatic system.
lymphatic system	(lim-fat´ik) The lymphatic vessels and lymph nodes.
lymphatics	(lim-fat'iks). Lymphatic system; lymphatic glands and lymphatic vessels, which pervade body and which collect and convey lymph.
lymphocyte	The white blood cell that plays an active role in providing immunity for the body by producing antibodies; it is the most radiosensitive blood cell.
lymphoma	Neoplastic disorder of lymphoid tissue.
lysosome	Cell that contains enzymes capable of digesting cellular fragments.
lytic	Destructive.

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