- 1. One of the subdivisions of an organ or other part, bounded by fissures, sulci, connective tissue septa, or other structural demarcations. 2. A rounded projecting part, as the l. of the ear. SEE ALSO: lobule. 3. One of the larger divisions of the crown of a tooth, formed from a distinct point of calcification. SYN: lobus [TA]. [G. lobos, l.]- azygos l. of right lung a small accessory l. sometimes formed above the hilum of the right lung; separated from the rest of the upper l. by a deep groove lodging the azygos vein. SYN: lobus azygos pulmonis dextri.- cerebral lobes SYN: lobi cerebri, under lobus.- ear l. SYN: lobule of auricle.- flocculonodular l. [TA] the small posterior and inferior subdivision of the cerebellar cortex that borders the line of attachment of the choroid roof of the rhomboid fossa, and consists of the left and right flocculus together with the unpaired nodulus (the most posterior of the folia composing the vermis cerebelli). Its major afferent connections come from the vestibular nuclei and directly from the vestibular nerve; it projects largely to the vestibular nuclei, directly and by way of the fastigial nucleus. SYN: lobus flocculonodularis [TA].- frontal l. of cerebrum [TA] the portion of each cerebral hemisphere anterior to the central sulcus. SYN: frontal l. [TA], lobus frontalis [TA].- inferior l. of (left / right) lung it is located below and behind the oblique fissure and contains five bronchopulmonary segments: superior (S VI), medial basal (S VII), anterior basal (S VIII), lateral basal (S IX), and posterior basal (S X). SYN: lobus inferior pulmonis dextri et sinistri [TA], lower l. of lung.- kidney lobes [TA] one of the subdivisions of the kidney, consisting of a renal pyramid and the cortical tissue associated with it. SYN: lobus renalis [TA], renal l..- left l. [TA] the left subdivision of several glands, e.g., prostate, thyroid, thymus. SYN: lobus sinister [TA].- left l. of liver [TA] it is separated from the much larger right l. anterior and superior to the falciform and coronary ligaments, and from the quadrate and caudate lobes by the fissure for the ligamentum teres and the fissure for the ligamentum venosum. The lobes of the liver are not functional units, being defined by external structures; the distribution of the portal vein, hepatic artery, and bile ducts does not correspond to the gross lobar divisions of the liver. SYN: lobus hepatis sinister [TA], divisio lateralis sinistra, lateral division of left liver.- limbic l. [TA] as originally defined by P. Broca : the nearly closed ring of the brain structures surrounding the hilus, or margin, of the cerebral hemisphere of mammals; it is composed of the fornicate gyrus (cingulate gyrus, fasciolar gyrus, parahippocampal gyrus, and uncus), and the hippocampus. See limbic system. SYN: lobus limbicus [TA].- lobes of mammary gland [TA] the 15–20 separate portions of the mammary gland that radiate from the central area deep to the nipplelike wheel spokes and make up the body of the mammary gland; each is drained by a single lactiferous duct. SYN: lobi glandulae mammariae [TA].- middle l. of prostate [TA] the portion of the prostate lying between the urethra and the ejaculatory ducts; indistinct unless hypertrophied. SYN: lobus medius prostatae [TA], Morgagni caruncle.- middle l. of right lung [TA] it is located anteriorly between the horizontal and oblique fissures and includes lateral (S IV) and medial (S V) bronchopulmonary segments. SYN: lobus medius pulmonis dextri [TA].- neural l. of hypophysis the bulbous part of the neurohypophysis attached to the hypothalamus by the infundibulum. It is composed of pituicytes, blood vessel s, and terminals of nerve fibers from the supraoptic and paraventricular nuclei.- occipital l. of cerebrum [TA] the posterior, somewhat pyramid-shaped part of each cerebral hemisphere, demarcated by no distinct surface markings on the lateral convexity of the hemisphere from the parietal and temporal lobes, but sharply delineated from the parietal l. by the parieto-occipital sulcus on the medial surface. SYN: lobus occipitalis [TA], occipital l. [TA].- parietal l. of cerebrum [TA] the middle portion of each cerebral hemisphere, separated from the frontal l. by the central sulcus, from the temporal l. by the lateral sulcus in front and an imaginary line projected posteriorly, and from the occipital l. only partially by the parieto-occipital sulcus on its medial aspect. SYN: lobus parietalis [TA], parietal l. [TA].- placental lobes cotyledons of the human placenta, viewed on the maternal surface as irregularly shaped elevations or lobes.- polyalveolar l. a type of congenital anomaly where a severalfold increase in the total alveolar number leads to congenital lobar emphysema.- l. of prostate [TA] one of the lateral lobes (right or left) or the middle l. or isthmus of the prostate; in the adult the lobes are ill-defined. SYN: lobus prostatae [TA].- pyramidal l. of thyroid gland [TA] an inconstant narrow l. of the thyroid gland that arises from the upper border of the isthmus and extends upward, sometimes as far as the hyoid bone; it marks the point of continuity with the thyroglossal duct. SYN: lobus pyramidalis glandulae thyroideae [TA], Lallouette pyramid, Morgagni appendix, pyramid of thyroid.- quadrate l. 1. a l. on the inferior surface of the liver located between the fossa for the gallbladder and the fissure for the ligamentum teres; 2. SYN: quadrangular lobule. 3. SYN: precuneus.- Riedel l. an occasional tonguelike process extending downward from the right l. of the liver lateral to the gallbladder; a similar process may, though rarely, extend from the left l.. SYN: lobus appendicularis, lobus linguiformis.- right l. [TA] the right subdivision of several glands, e.g., prostate, thyroid, thymus. SYN: lobus dexter [TA].- right l. of liver [TA] the largest l. of the liver, separated from the left l. anteriorly and superiorly by the falciform and coronary ligaments and from the caudate and quadrate lobes by the sulcus for the vena cava and the fossa for the gallbladder. SYN: lobus hepatis dexter [TA].- superior l. of (right/left) lung the l. of the right lung that lies above the oblique and horizontal fissures and includes the apical (S I), posterior (S II), and anterior (S III) bronchopulmonary segments; in the left lung, the l. lies above the oblique fissure and contains the apicoposterior (S I + II), anterior (S III), superior lingular (S IV), and inferior lingular (S V) segments. SYN: lobus superior pulmonis (dextri et sinistri) [TA], upper l. of lung.- supplemental l. in dental anatomy, an extra l.; one that is not included in the typical formation of a tooth.- temporal l. [TA] a long l., the lowest of the major subdivisions of the cortical mantle, forming the posterior two-thirds of the ventral surface of the cerebral hemisphere, separated from the frontal and parietal lobes above it by the lateral sulcus arbitrarily delineated by an imaginary plane from the occipital l. with which it is continuous posteriorly. The temporal l. has a heterogeneous composition : in addition to a large neocortical component consisting of the superior, middle, and inferior temporal gyri and the lateral and medial occipitotemporal gyri, it includes the largely juxtallocortical parahippocampal gyrus with its paleocortical (olfactory) uncus and, beneath the latter, the amygdala. SYN: lobus temporalis [TA], temporal cortex.- lobes of thyroid gland [TA] the two major divisions of the gland lying on the right and left side of the trachea and connected by the isthmus. A smaller pyramidal l. is frequently present as an upward extension from the isthmus. SYN: lobi glandulae thyroideae [TA].
* * *a) a more or less rounded projection of a body organ or part <the \lobe of the ear>b) a division of a body organ (as the brain, lungs, or liver) marked off by a fissure on the surface
* * *n.a major division of an organ or part of an organ, especially one having a rounded form and often separated from other lobes by fissures or bands of connective tissue. For example, the brain, liver, and lung are divided into lobes.• lobar adj.
* * *(lōb) [L. lobus, q.v.] 1. a more or less well-defined portion of any organ, especially of the brain, the lungs, or a gland. Lobes are demarcated by fissures, sulci, connective tissue, and shape. Called lobus in official anatomical nomenclature. 2. one of the main divisions of the crown of a tooth, developmentally representing a center of calcification.
Medical dictionary. 2011.