The correct answer is A. Raising his eyebrows
Correct Answer Explanation
Temporal nerve injury may cause permanent paralysis of the ipsilateral frontalis muscle, causing loss of horizontal forehead rhytides and descent of the brow on the affected side. The temporal branch of the facial nerve courses between the superficial and deep temporalis fascia, penetrating the underside of the frontalis muscle from its lateral edges. It lies in the subcutaneous fat overlying the SMAS of the temple and lateral forehead region. The greatest potential for nerve damage lies in the lateral regions of the face. In 15% of patients, there is a cross-innervation to the frontalis muscle by the more inferior zygomatic branch of the facial nerve. In the other 85% of patients, violating the temporal nerve results in motor denervation and the inability to raise a “droopy” eyebrow. Flattening of the forehead with diminished visibility of wrinkles and skin tension lines on the ipsilateral side is easily noticed. Over time, the inability to raise the eyebrow can lead to eyebrow and lid ptosis and upper visual field compromise as muscular disuse atrophy progresses.
Incorrect Answers Explanation
B – The marginal mandibular branch of the facial nerve innervates the lip depressors. Injury can cause asymmetry when smiling or grimacing.
C – The marginal mandibular branch of the facial nerve innervates the lip depressors. Injury can cause asymmetry when smiling or grimacing.
D – The zygomatic branch of the facial nerve innervates the orbicularis oculi muscles. An injury can lead to inability to completely appose the upper and lower eyelids and subsequent corneal desiccation. 5 – The marginal mandibular branch of the facial nerve innervates the lip depressors. Injury can cause a compromise in mouth function, resulting in drooling.