When Solomon wrote of "the silver cord be loosed," he was, in context, writing very figuratively of the degeneration of the physical body over time and its termination.
Ecclesiastes 12:1-8
1 Remember also your Creator in the days of your youth, before the evil days come and the years draw near when you will say, "I have no delight in them";
Here, Solomon contrasts "the days of your youth" with the "evil days" when his reader no longer delights in them as he did in his youth. Why doesn't the reader delight any longer in the passing days? Because the days of youth are well in the past, before the afflictions of old age, which Solomon goes on to describe in a very figurative and amusing way.
2 before the sun and the light, the moon and the stars are darkened, and clouds return after the rain;
This is a reference to the eyes that "darken" in their capacity to see, growing cloudy and dim, as aging eyes often do.
3 in the day that the watchmen of the house tremble, and mighty men stoop, the grinding ones stand idle because they are few, and those who look through windows grow dim;
Here, Solomon describes the legs as "the watchmen of the house" that tremble, the "mighty men that stoop" represent the shoulders, a perennial symbol of manly strength, and "the grinding ones that are idle because they are few" picture the decayed and absent teeth of an elderly person.
4 and the doors on the street are shut as the sound of the grinding mill is low, and one will arise at the sound of the bird, and all the daughters of song will sing softly.
Since the teeth are few, and eating is not as enjoyable, "the doors on the street are shut," which are the lips. Seniors often grow jumpy, too, as Solomon points out here, starting at the sudden trill of a bird, and so those caring for them "sing softly" around them.
5 Furthermore, men are afraid of a high place and of terrors on the road; the almond tree blossoms, the grasshopper drags himself along, and the caperberry is ineffective. For man goes to his eternal home while mourners go about in the street.
The elderly cease to find excitement in risk and so avoid "high places" from which they might fall and "terrors on the road," which are occasions of confrontation and aggression. Their hair "blossoms as an almond tree" turning white with age, and they go about like an injured or dying grasshopper, stiff and heavy, dragging itself along. As well, upon the elderly, the caperberry, an ancient eating stimulant, no longer works to produce hungriness.
6 Remember Him before the silver cord is broken and the golden bowl is crushed, the pitcher by the well is shattered and the wheel at the cistern is crushed;
In keeping with his figurative description of the aged person, Solomon continues to render their condition in an artful way, the "silver cord," "golden bowl," the shattered "pitcher," etc., all referring to the termination of life, the physical body no longer fit for purpose, returning to the dust of the earth.
7 then the dust will return to the earth as it was, and the spirit will return to God who gave it.
8 "Vanity of vanities," says the Preacher, "all is vanity!"
Does Solomon mean to indicate that there is a literal "silver cord" within a person that at death actually breaks? No, in context, he is just offering a figurative description of aging and death, nothing more.
