What are bunny lines and how are they formed according to the chapter?

Bunny lines are wrinkles formed on the lateral and dorsal aspects of the nose due to the contraction of the nasalis muscle. They are part of facial expressions like frowning, squinting, or smiling and can be accentuated by botulinum toxin treatments in the upper face.

Bunny lines, also known as nasalis rhytids, are wrinkles that appear on the lateral and dorsal aspects of the nose. They typically run diagonally over the nasal sidewalls and nasal bridge. These lines are formed due to the contraction of the nasalis muscle, which draws the nasal sidewalls superiorly and medially. Bunny lines can become more pronounced with facial expressions such as frowning, squinting, or smiling and may be accentuated by botulinum toxin treatments targeting other areas of the upper face, like frown lines and crow's feet. Treatment with botulinum toxin can reduce these lines by inhibiting the contraction of the nasalis muscle, thereby smoothing the overlying skin.