Tabs and accordions are created using jQuery UI and include aria labels and other helps to make them keyboard and screen-reader accessible.

From theĀ jQuery UI Website:

Deep accessibility support

Widgets should also be accessible to JavaScript-capable users who have disabilities such as blindness or deafness (should we ever venture into the arena of audio/video integration, for instance). We attempt to make components accessible through the use of semantic HTML elements within components and following the guidelines specified in the WAI-ARIA spec.