Which statement best describes the action of the zygomaticus major muscle?

• A. It elevates and draws the corner of the mouth laterally (as in smiling).
• B. It compresses the cheeks against the teeth during chewing.
• C. It closes the eyelids by pulling them medially.
• D. It depresses the mandible to open the mouth.

Answer: (A)

Verified step by step guidance

1. Identify the primary function of the zygomaticus major muscle by recalling its anatomical location and role in facial expression. The zygomaticus major extends from the zygomatic bone (cheekbone) to the corner of the mouth.
2. Understand that muscles attached to the corner of the mouth typically influence movements such as smiling, frowning, or other expressions involving the lips.
3. Recall that the zygomaticus major muscle's main action is to pull the corner of the mouth upward and laterally, which creates a smile.
4. Compare this action with the other options: compressing cheeks (buccinator), closing eyelids (orbicularis oculi), and depressing the mandible (digastric or other muscles). These are functions of different muscles.
5. Conclude that the statement 'It elevates and draws the corner of the mouth laterally (as in smiling)' best describes the action of the zygomaticus major muscle.