Article iii of the constitution establishes a single . article iii also givesthe power to create "inferior," or lower courts.

1. For the first one here the missing part would be Supreme Court. Article II of the Constitution  establishes a single Supreme Court. In the Constitution it says :"The Judicial Power of the United States shall be vested in one supreme Court". To power to interpret the laws lays within the Supreme Court and the inferior courts.
2. The power to create lower courts, that is "inferior" courts is vested to the Congress of the United States. As it says in Article III: " and in such inferior Courts as the Congress may from time to time ordain and establish." The lower courts that the Congress establishes are inferior to the Supreme Court and thus are termed "inferior", the rulings of the Supreme Court apply to all lower courts.