Let me see if I can help:

From L1-L5 there are rear disc bulges.

At L4-5 "Ligamentum Flavum" hypertrophy ~ The ligamentum flavum is a series of ligaments of yellow elastic tissue connecting the laminae of adjacent vertebrae from the axis to the sacrum. You have an overgrowth of this tissue.

L5-S1 The herniation is decreased in size but it touches the L5-S1 nerve root.
You also have ligamentum flavum hypertrophy here too. There is facet joint degeneration. The facets are those "wing-like" structures on each side of your spine - you can see them if you hunch your back. They stick out down the middle of your back on each side of the spine. You mention dessication at L5-S1, and you're fortunate it's not the whole spine. Dessication is drying out of the discs, and we get that with age, although some of us get it earlier than others. When the discs dry out, they tend to "squish" down & flatten, causing them to bulge/herniate.

I hope this helped a little. If you have more questions, let me know. Hugs, Lee