The eyebrows have an important protective function for our eyes. They prevent sweat from running into the eyes and protect against dust and dirt. Additionally, the eyebrows have a supporting function of the eyelashes. The eyebrows are also important for facial expressions, as they underline or complete some facial expressions.
Anatomy of the eyebrows
The eyebrows themselves are two strips of hairs above the orbit. These hairs grow very quickly and fall out again after about eight weeks. They are more pigmented and thicker than the hair on the head and other parts of the body hair.
The terminal hair consists of three characteristic layers. The hair medulla is located inside the hair and consists largely of fats (lipids). The hair cortex makes up the main part of the hair and consists mainly of keratin fibres, which guarantee the tear resistance of the hair and give the hair its structure.
The last layer of the hair is called the cuticle layer. Here the cells are arranged overlapping like roof tiles. This layer is the protective layer.
There are four facial muscles that guarantee the movement of the eyebrows. These are mainly the frontal muscle of the skull (Musculus occipitofrontalis), the eyebrow furrow (Musculus corrugator supercilii), the eyebrow lowering muscle (Musculus depressor supercilii) and the nose root furrow (Musculus procerus). Each of these muscles has a specific function, which is especially important for facial expression and non-verbal communication. The frontal muscle of the skull raises the eyebrows, the eyebrow frowner pulls the eyebrows inwards and downwards, the eyebrow dropper pulls the eyebrows downwards and the nose root frowner creates the frown line between the eyebrows.
The colour of the eyebrows, like all colours, is caused by the absorption and reflection of light of different wavelengths. The light that is emitted and reaches our retina triggers signals there that are interpreted by our brain as colour. Which wavelength is absorbed and which colour is created by it is determined in the eyebrows mainly by the content of an organic pigment, melanin.
Eumelanin tends to produce dark, brown-black colours. Pheomelanin is responsible for lighter, blonde-red colours. Often both types of melanin are present at the same time, but in different amounts.
The colour of the eyebrows is often similar to the colour of the head hair, but can also differ from it. Eyebrows can also turn grey with age. The eyebrows can also be tinted, whereby special attention should be paid to the compatibility of the tint. Do you have further interest in this topic?