Eyebrow Anatomy and Shape
The eyebrow is an important part of facial symmetry and contributes to the aesthetic appearance of men and women. Eyebrows frame the face and draw attention to the eyes and represent the first facial structures we look at as a society and thus have a significant impact on a person’s appearance. It has an important role in human communication and facial expression for this reason, many women feel distressed if they experience the loss of their eyebrows. It is common in human over history to change their eyebrow shape and thickness by removal, make up or tattoo according to their tribe, culture or the fashion at their time.
The eyebrow is an area of thick, delicate hairs on the brow ridge above the eyes and its follows the shape of the lower margin of the brow ridges in human. Main function is to prevent sweat, water, dandruff and other debris from falling down from scalp and forehead into the eye besides, they help shield the eyes from sun.
Average Growth Rate
On average, it takes about 6-8 weeks for eyebrow to grow in, for the average pre-puberty and post-pubescent child, hair grows in at about 0.14 mm each day. For an adult and an elder, hair grows at a rate of about 0.16 mm. daily. Eyebrows have the slowest rate of regrowth on the body compared with hair on the scalp and body hair as its growth cycle can last 12-15 weeks
Each phase has specific characteristic that determine the length and fullness of the hair.
Phase I (Anagen Phase): hair follicle active growth phase. During this phase root of the hair divides rapidly adding hair to the shaft. this phase determines the length of the hair. It can last between 30-45 days.
Phase II (Catagen Phase): is a short transition stage that occurs at the end of the Anagen phase. Catagen phase cuts the hair off from its blood supply and from the cells that produce new hair. The growth stops, and the hair follicle shrinks. this when some hair will shed and all out. as soon as the follicle is complete in the catagen phase then it will move on to the last phase.
Phase III (Telogen): is the resting phase and lasts for 2-4 months. Approx. 14% of the hair is in the resting phase. During this time the hair does not grow and remans inactive. The hair stays attached to the follicle while the dermal papilla stays in the resting phase below.
At the end of the telogen phase the hair follicle re-enters the Anagen (growing) phase. The dermal papilla and the base of the follicle join together again, and a new hair begins to form. Medications (certain drugs) and certain diseases such as cancer drugs and thyroid disease can cause eyebrow to take longer growth cycle than the initial 12-15 weeks to grow.
Eyebrow hair that is plucked or threaded begins regrowing after about 2-3 weeks. Plucking involves using tweezers to remove the hair by its root from the hair follicle. Threading involves dragging a piece of cotton thread across the surface skin and removing hair in it is path. As with tweezing, hairs are removed by the root.
Consistent eyebrow removal can eventually lead to diminish growth, thinning eyebrow and dormant follicles, especially after the age of 40s.
Anatomy of the Eyebrows
Can be divided into 3 parts: head, body and tail. The head is the most medial portion of the eyebrow, measuring 5-10 mm in length, and is usually below the orbital margin, with the hairs oriented vertically. The body is approximately 25-30 mm long and is usually the densest, widest, and most prominent portion of the eyebrow. The hairs in this part is directed obliquely or horizontally. The tail is approximately 10 mm long, is the narrowest portion of the eyebrow with the least density especially end part of it and lies above the orbital margin.
Eyebrow hair can vary according to ethnicity, with Asians possessing thinner, very straight-growing hairs and African possessing thicker hair with an extensive curt.
Men and women have distinguishing differences in their eyebrow. Men typically have thicker eyebrows that are horizontal. Whereas women have a more delicate and more elegant defined shape.
Proper angulation of the hair follicle is the most important feature of any eyebrow transplant. The hair in the supper part of the central edge of the eyebrow usually points upward to the hairline, while the hair on the lateral aspects points horizontally, towards the ears. The hair in the upper part of the eyebrow should pointed slightly downward and the lower portion slightly upward, so that they will coverage in the middle, forming a slight ridge and resembling the pattern of a feather.
Eyebrow Shape Types
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