Pneumatic artificial muscles Pneumatic artificial muscles Pneumatic artificial muscles (PAMs) are contractile or extensional devices operated by pressurized air filling a pneumatic bladder. In an approximation of human muscles, PAMs are usually grouped in pairs: one agonist and one antagonist. PAMs were first developed (under the name of "McKibben Artificial Muscles") in the 1950s for use in artificial limbs. The Bridgestone rubber company (Japan) commercialized the idea in the 1980s under the name of Rubbertuators. The retraction strength of the PAM is limited by the sum total strength of individual fibers in the woven shell. The exertion distance is limited by the tightness
The King of Limbs made Donwood think of "immense multicoloured cathedrals of trees, with music echoing from the branches whilst strange fauna lurked in the fog". Donwood and Yorke drew trees with eyes, limbs, mouths, and familiars, creating "strange, multi-limbed creatures that are neither malevolent or benevolent", inspired by Northern European fairy tales. For the special "newspaper" edition of "The King of Limbs", Donwood wanted to create something "in a state of flux". He chose newspaper, which fades in sunlight, for "its ephemeral nature"; this reflected the album's nature themes, mirroring the natural decay of living things. To design the newspaper, Donwood took inspiration