Final answer:
The corrugator supercilii is the muscle deep to the orbicularis oculi and is involved in moving the eyebrows, contributing to facial expressions.
Step-by-step explanation:
The muscle that is deep to the orbicularis oculi and involved in facial expression, specifically the movement of the eyebrows, is the corrugator supercilii. The orbicularis oculi acts to close the eye, but the corrugator supercilii draws the eyebrows medially and downward, creating a frown or a 'concerned' expression. This muscle plays a crucial role in non-verbal communication by contributing to facial expressions that convey various emotions.