myoneural [mÄ«â²Å-nÅ«â²rÄl] Type:Term. Definitions 1. Relating to both muscle and nerve; denoting specifically the synapse of the motor neuron with striated muscle fibers: myoneural junction or motor endplate. Stedmanâs Medical Dictionary Â© Wolters Kluwer Health.
On 16-Aug-1960, Captain Joseph Kittinger of the US Air Force parachuted from a helium balloon at an altitude of 102,800 ft (19.5 miles / 31,354m) setting three world records; the highest parachute jump, the longest free fall (85,300 ft in 4 mins 36 seconds) and the first person to break the speed of sound without an aircraft (714 mph).
Here I'll assume you're talking about the drogue parachutes, the first ones out. They were deployed at 24,000 feet (7315.2m). The density of the air at that altitude is, according to Wolfram|Alpha, $0.57~\textrm{kg/m}^3$. So now we have all our numbers.