In yoga, Indian medicine and Indian martial arts, prana (प्राण, prāṇa; the Sanskrit word for breath, "life force", or "vital principle") permeates reality on all levels including inanimate objects. In Hindu literature, prāṇa is sometimes described as originating from the Sun and connecting the elements. Five types of prāṇa, collectively known as the five vāyus ("winds"), are described in Hindu texts. Ayurveda, tantra and Tibetan medicine all describe prāṇa vāyu as the basic vāyu from which the other vāyus arise. Prana is divided into ten main functions: The five Pranas – Prana, Apana, Udana, Vyana and Samana – and the five Upa-Pranas – Naga, Kurma, Devadatta, Krikala and Dhananjaya. Pranayama, one of the eight limbs of yoga, is intended to expand prana.