umbo


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

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 ?
Effects of SSCD and Its Repair on Movement of the Umbo, Stapes Head, and RWM and the Effects of Location of Dehiscence according to LDV Measurements.
Alternatively, in a functionally relevant approach, the main traits of the shape of shell outline may be synthetically characterised by (i) the shell elongation, that is, the ratio of contour length to contour height, (ii) the valve dissymmetry, namely, the degree of dissymmetry of the position of the umbo versus the anterior and posterior extremities of shell, and (iii) the ventral convexity, that is, the degree of prominence of the ventral side of the shell outline, opposite to umbo.
where v is footplate velocity, PTM is sound pressure at umbo, f is frequency, and D is footplate displacement.
In bivalves, the shell-growth process has frequently been schematised using a set of vectors diverging from the valve umbo and rejoining the valve margin [8-10], the length of each vector thus representing the relative growth progress in the corresponding direction.
Pilsbry (4,7) referred Triassic freshwater mussels from the Newark Supergroup to modern South American families Mycetopodidae based on similarity of shell shape and Hyriidae based on radial umbo sculpture (5).
umbo ug, arks pencer Jumbo Joy mug, PS9.50, Marks & Spencer Scandi drinking glass, PS1 each, Tesco Pine wreath, PS30; vintage glass tabletop trees, from PS15; pre-lit wooden church, from PS12; decorations, from PS2.50; mistletoe and holly fill-your-own crackers, PS5 for six, all John Lewis.
The rounded end near the umbo is the anterior and is the thickest part of the shell while the posterior end is the thinner area.
The lesion had extended from slightly below the level of the pyramidal process to just anterior to the cochleariform process; it did not extend below the level of the umbo.
The police acted after the protesters pelted them with stones in the town of Kom Umbo, the source said.
If the Pentamerus oblongus were still there, the tip, or umbo, of the fossilized shell would protrude from the rock.
They found the umbo - where the eardrum connects to the hammer or malleus - produced the greatest sound vibration, particularly if the incus or anvil bone first was removed surgically.
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.