umbo

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Related to umbos: Umbo of tympanic membrane

umbo

 [um´bo] (L.)
1. a rounded elevation.
2. the slight projection at the center of the outer surface of the tympanic membrane.

um·bo

, gen.

um·bo·nis

, pl.

um·bo·nes

(ŭm'bō, -bō-nis, -bō-nēs),
1. A projecting point of a surface.
2. Umbo of tympanic membrane.
[L. boss of a shield, a knob]

umbo

(ŭm′bō)
n. pl. umbos or umbones (ŭm-bō′nēz)
A small anatomical projection on a surface, such as that on the inner surface of the eardrum at the end of the manubrium of the malleus, corresponding to the most elevated point of the eardrum.

um′bo·nal (ŭm′bə-nəl, ŭm-bō′nəl), um·bon′ic (ŭm-bŏn′ĭk) adj.

um·bo

, pl. umbones (ŭm'bō, -nēz) [TA]
1. A projecting point of a surface.
2. [TA]
Synonym(s): umbo of tympanic membrane.
[L. boss of a shield, a knob]

umbo

the pointed centre of a clam shell, being the oldest part around which are many concentric lines of growth.

umbo 

An area (0.15 mm-0.20 mm) in the centre of the foveola. Stimulation of this area results in the highest visual acuity.
References in periodicals archive ?
Morphological larval features of species within the genus Crassostrea include (1) a knobby or beak-shaped umbo directed posteriorly; (2) shell height that is generally greater than shell length; (3) provinculum length that ranges from 68 to 88 [micro]m; (4) the presence of two rectangular teeth on each side of the provinculum; (5) a well-defined central apparatus; and (6) posterior obscured teeth.
Post-larval features of species within the genus Crassostrea include (1) a left valve umbo that is beak shaped and skews backward; (2) two posterior hinge teeth in shells up to 500 [micro]m in length; and (3) a ligament that is 40 [micro]m from the anterior end of the provinculum.
La concha es solida algo alargada y de forma oblicua, los picos son subcentrales y los umbos bajos, el extremo anterior es mas corto y su borde es redondeado; el lado posterior se estrecha hacia el borde ventral terminando en un extremo punteado romo, un lomo anguloso delimita la vertiente posterior; escultura con anchas y bajas costillas redondeadas muy juntas y algo oblicuas en el umbo y en el disco, se suavizan y se convierten en lineas en las vertientes anterior y posterior asi como cerca al borde ventral de la valva; charnela tiene un ligamento interno delgado y en la valva derecha un gran diente cardinal que encaja en el condroforo de la valva izquierda; las inserciones de los musculos aductores y la linea paleal entera nitidamente marcadas, los bordes de las valvas lisos.
Concha solida, subtriangular, umbo cerca del extremo posterior con pico opistogirado, borde anterodorsal suavemente arqueado con extremo redondeado, extremo posterior anguloso y borde ventral arqueado; charnela taxodonta, con 20 dientes anteriores y 10 posteriores, el condroforo es oblicuo y profundo; color externo blanquecino con periostraco pardo olivaceo, brillante y muy adherente, el cual deja ver finas estrias concentricas en la conchilla; interior blanco nacarado y bordes de las valvas lisos.
Even if rarely visible, probably due to the acid waters that dissolve the umbo (Radley and Barker, 1998, and Munt personal communication), the ornamentation was present only on juveniles (Fig.
Mussels initially demonstrate preferential orientation with umbos towards the center of the sock and valve opening towards the outside, presumably to alleviate mechanical stress on valves and allow adequate filtration.
Mussel shells were first sectioned through the umbo and epoxied to a microscope slide or plexiglass plate, depending on size.