There is a one vertical Procerus muscle and two Corrugator muscles that cause wrinkles and frowning in the area between the eyebrows.
The frotanus muscle runs upwards from the bridge of the nose and inserts into the skin.
Muscle fibres run upwards along the muscle and, when they contract, this produces shortening of the muscle and a cross line transverse (horizontal line at the upper bridge of the nose).
The Corrugate muscles run upwards and sideways from the bone in the frown area to the skin above the inner aspect of the eyebrow.
When these muscles contract they pull the eyebrows inwards, downwards and cause either vertical or slightly slanted lines on either side of the frown areas.
The muscles run in different directions and therefore the contractions cause lines in different orientation. It is important to know which muscle is responsible for which line when treating the frown area with Botox in order to correctly target the right muscle. In future blog posts we’ll talk about variation in muscles between other people and tell-tale signs if someone has had Botox Therapy.