“Or ever the silver chord be loosed, or the golden bowl be broken.”
The loosed silver cord is believed to denote the spinal column and therefore the physical infirmities (stooped back) of age. The golden bowl is believed to denote the brain and the gradual decline of mental powers, which in dotage is described as senility.
“Or the pitcher be broken at the fountain.”
Having a desire to urinate, but being unable to do so.
“Or the wheel broken at the cistern.”
The body contains all its blood, (the cistern is full), but the heart’s pumping action (the wheel) ceases.