上顎

1. Origins, structure, and basic meaning

• Structure: 上顎 is read じょうがく and means the upper jaw.
• Basic usage: It is used when comparing its position with the lower jaw on a model or observing teeth on a fish's upper jaw.

2. Common pitfalls and similar expressions

• Contrast with the lower jaw
  • 上顎と下顎 refers to the upper and lower jaws together.
• Possessive relation
  • 魚の上顎 identifies the upper jaw of a fish.