Thomas Aquinas Commentary Lamentations 3:7-9

"He hath walled me about, that I cannot go forth; he hath made my chain heavy. Yea, when I cry, and call for help, he shutteth out my prayer. He hath walled up my ways with hewn stone; he hath made my paths crooked." — Lamentations 3:7-9 (ASV)

Here he excludes any means of escape.

1. Because of the enemy's siege. The text says, he has built against me all around, which refers to an army of besiegers. The word fetters signifies the same thing, just as those thrown into prison are unable to flee. As it is written, I was delivered up and could not get out (Psalms 87:9), and, You have put my feet in the stocks and have observed all my paths (Job 13:27).
2. Because their prayer is shut out: Yes, and when I cry and plead, he has shut out my prayer. As the psalmist says, I will cry by day, and you will not hear (Psalms 21:3).
3. Because their plans are obstructed. The text says, He has shut up my ways—their plans for escape—with hewn stones, which are serious obstacles. As God says elsewhere, I will hedge up your way with thorns (Hosea 2:6).