"Nerviosa" refers to the wood's dimensional stability (or lack thereof). It’s related to the shrinkage (specifically, the ratio between the radial and tangential shrinkage).

1.Densidad (peso de la madera por metro cúbico). Una curiosidad: a partir de 1000 KG no flotan.
***2- Coeficiente de contracción volumétrico: define la madera como nerviosa o estable***
3- Dureza (Monnin).
4- Durabilidad: una clasificación en base a pruebas de laboratorio.
http://www.facilisimo.com/foro/facildehacer/?id=9483

COEFICIENTE DE CONTRACCIÓN VOLUMÉTRICA
Dicho coeficiente mide la variación del volumen de la madera cuando su humedad varía un 1%.
Este coeficiente V% (casi constante entre los estados anhídro y de saturación de las fibras) caracteriza las maderas:
****- Maderas de débil contracción 0,15% < V < 0,35% (poca nerviosa) maderas de carpintería y ebanistería.
- Maderas de contracción media: 0,35% < V < 0,55% (maderas de construcción).
- Maderas de fuerte contracción: 0,55% < V < 1% (nerviosa) Emplear en medios de humedad constante.****
http://www.geocities.com/cokevilchez/madera.htm

Volumetric Shrinkage- Answers the question, "How stable is the wood?". Table values are percent shrinkage from green to ovendry. This value is useful for comparisons to other species. As an example, a ponderosa pine board will shrink, on the average, 9.7% in total volume from green to oven dry. Western juniper will only shrink 82% as much as ponderosa pine. Actual inches of shrinkage in the radial and the tangential direction may be calculated using published shrinkage coefficients.
http://juniper.oregonstate.edu/primary.php

Stability: Dimensional stability in service associated with changes in humidity levels. Rankings based on average seasonal movement of kiln dried wood: low (not stable); medium (fairly stable); high (very stable).
http://www.woodbin.com/calcs/wdpick.htm

Stability is anticipation of how much effect temperature and humidity will have upon the wood. All wood continues to absorb and lose water, depending on the humidity of its environment. Putting on a finish just slows down the exchange. Wood expands as it absorbs water. Unfortunately wood expands a different amount in each of its three different directions, longitudinally (up and down the tree) radially (in and out from the core of the tree) and tangentially (around the tree). A wood that has high stability has little difference in expansion in the various directions. A wood that has low stability has a larger difference.
http://www.davidreedsmith.com/WoodTerm.htm


So, the more “nerviosa” the wood is, the lower the stability. Yours would be medium.


White Oak is a pale yellow brown and has straight grain and medium to coarse texture. It has medium strength and is springy. It has ***medium stability.***
http://www.davidreedsmith.com/Shuttles/Whiteoak.htm

Movement in Service - Black maple is reported to have ***medium dimensional stability*** after seasoning, and tends to move moderately in use.
http://www.badgerwood.com/desc/hmdesc.htm