What is known as "Long Arm"? Plainly put, it just means having long arms.
Liu Bei, Zhang Bolun, Lu Fei... You must know of these characters, all quite capable.
But their "long arms" are due to physical stature, whereas in Martial Arts, "Long Arm" can have another meaning.
Huang Baijia once ranked Long Arm Skill at the pinnacle of Internal Boxing in his book on the subject, saying, "Blessed with divine Long Arm, the best indeed, It locks deep the fighting door and turns men into heroes of breed. As immortals stand reaching for the sky, Withdrawing to embrace the moon, never shy. Whipping left and right, beyond peers' reach, Blasting hammers charge, with wings they beseech."
Please note that the mentioned "Long Arm" isn't the same as "Long Spine"; they're actually two different concepts, but they often get confused in later generations.
