Which muscle runs along the mid-line from the chin to the lower lip and pulls the lower lip straight downward?

• A. Procerus Muscle
• B. Nasalis
• C. Depressor Anguli Oris
• D. Depressor Labii Inferioris

Answer: (D)

The movement described is produced by a muscle that starts on the lower jaw near the chin and inserts into the lower lip, pulling it straight downward. That muscle is the depressor labii inferioris. When it contracts, it draws the lower lip downward and slightly outward, giving a pout or downturned mouth.

The other muscles mentioned don’t run along that midline to the lower lip: the procerus sits between the eyebrows and wrinkles the skin of the nose/forehead; the nasalis covers the nose and helps with nostril movement; the depressor anguli oris attaches at the corners of the mouth and pulls those corners downward, not the entire length of the lower lip.