Facial lines and wrinkles (rhytides) form because of the following factors:

• Ageing processes, Sun damage, Muscle movement, Gravity, Injury Smoking

There is often a degree of asymmetry to the lines, as people tend to smile or frown more on one side than the other, or consistently sleep on the right or the left cheek.

Fine lines

Fine lines and wrinkles arise because of irregular thickening of the dermis and because of a decrease in the amount of water held by the epidermis. This is mainly caused by sun damage and exposure to environmental toxins particularly tobacco smoke.

Furrows

Deeper lines or furrows are classified as dynamic or static. Dynamic lines appear with movement i.e. the activity of facial muscles. Static lines are unchanged with muscle movement. Eventually dynamic lines become static.

• Crow’s feet around the eyes are due to smiling and activity of the eyelid muscles (orbicularis oculi). 
• Worry lines on the forehead are due to contraction of the frontalis muscle when raising the eyebrows
• Frown lines between the eyebrows are due to contraction of corrugator supercilii muscles and procerus muscle when concentrating or angry