The interior of the church has three naves, with the central nave being the widest. Their ribbed vaults are supported by octagonal columns that are 20 meters high. The Royal Chapel has walnut seats in the Plateresque style and a Renaissance pulpit from the 16th century, a work of J. Salas.

http://www.tripadvisor.co.uk/Travel-g187463-c143988/Palma-De...

Nervio o nervadura es un elemento constructivo formado por un segmento de arco saliente del intradós de una bóveda.

Se utilizó a partir del siglo XII al desarrollarse la bóveda nervada o de crucería.

http://es.wikipedia.org/wiki/Nervio_(arquitectura)

La bóveda de crucería, también llamada bóveda nervada, es un tipo de bóveda característica de la arquitectura gótica que recibe este nombre porque está conformada por el cruce, o intersección, de dos bóvedas de cañón apuntado. A diferencia de la bóveda de arista, la de crucería se caracteriza por estar reforzada por dos o más nervios diagonales que se cruzan en la clave, generalmente. La bóveda de crucería se considera uno de los tres elementos distintivos de la arquitectura gótica, junto con el arco apuntado y el arbotante.

http://es.wikipedia.org/wiki/Bóveda_de_crucería

The intersection of two or three barrel vaults produces a rib vault or ribbed vault when they are edged with an armature of piped masonry often carved in decorative patterns; compare groin vault, an older form of vault construction. While the mechanics of the weight of a groin vault and its transmission outwards to the supporting pillars remained as it had been, the new use of rib vaults demonstrates the skill of the masons and the grandeur of the new ideas circulating at the introduction of Gothic architecture in the end of the eleventh century.

http://en.wikipedia.org/wiki/Rib_vault

The use of stone ‘ribs’ forming pointed arches to support the ceiling of the nave was an important achievement, and Durham Cathedral is the earliest known example.

http://www.durhamworldheritagesite.com/architecture/cathedra...

The development of the pointed Gothic arch allowed church builders to span wide areas, and in the process helped develop new forms of vaulting based on stone or brick ribs. Gothic vaults were light and more flexible than barrel vaults. The first forms of ribbed vaults were quadripartite (four-part), with four ribs dividing each bay at a diagonal. The point at which the ribs met was the boss, a solid block of stone or wood which might be highly carved and painted. A further development was the sexpartite (six-part) vault, where each bay was divided by six ribs.

http://www.britainexpress.com/church-history.htm?term=Vaulti...