Gently simmer all ingredients except noodles in a 6-quart heavy pot, covered, skimming as needed, until pork is very tender, 1 1/2 to 2 hours.
Transfer pork to a bowl. Discard bones, spices, and garlic. Coarsely shred meat. Skim fat from broth, then return meat and bring to a simmer. Add noodles, then stir into broth and simmer, uncovered, stirring occasionally, until noodles are tender, about 6 minutes.