Eyebrows Anatomy .

eyebrow

1. Anatomy of Eyebrows by Sunny Biswas Eyebrows are a strip of short hairs located above each eye that follow the shape of the lower margin of the brow ridges. Eyebrows have two main functions i.e. to convey emotions through facial expression and to prevent sweat, water, and other debris from falling down into the eye socket.

2. Location of eyebrow 1 The two eyebrows are horizontally placed over the superciliary ridge of the frontal bone 2 Right and left eyebrows are separated from each other by a smooth hairless prominent area known as the glabella. 3 4 The eyebrows are a significant aspect of an individual's facial configuration as they separate the upper eyelids from the forehead. Each eyebrow is curved with the convexity of the curve directed upwards.

3. Hair of Eyebrows The surface of the eyebrows is covered by hair which forms an important part of the eyebrows. The pattern of hair growth gives the eyebrows a comma-shaped appearance. The head of the comma is directed medially and usually situated somewhat beneath the superior orbital margin. The hair in this area are generally directed upwards and somewhat medially. The body of the comma lies directly over the superior orbital margin; hair in this region are directed laterally, parallel to the plane of eyebrows. Laterally, the tail end of the comma-shaped eyebrow is placed above the lateralmost part of the superior orbital margin with the cilia pointing outwards and somewhat downwards. In some individuals, the two eyebrows meet in the centre above the root of the nose; a condition known as Synophrys . The hair of eyebrows are generally of three types:

4. Structure of the eyebrow

5. Contd. > The frontalis muscle: Origin - The epicranial aponeurosis Insertion - To the posterior surface of the eyebrow skin. Nerve S upply - Temporal branches of the facial nerve Function - Elevation of the eyebrow indirectly causes the upper lid to lift as well. The maximum action of the frontalis muscle results in a 3.5 mm increase in the elevation of the upper eyelid. This muscle is used in extreme upward gaze and when the levator is paralyzed. > The orbicularis oculi: Origin - The superciliary muscle originates on the frontal bone of the skull, just above the eye socket. The orbital part of the orbicularis oculi known as superciliaris muscle is inserted into the skin of the eyebrow. Nerve supply- T he temporal branch of the facial nerve Function- P ulling the entire eyebrow downwards and slightly medially. > The corrugator supercilia: Origin - F rom the medial end of the superciliary ridge and is located beneath the frontalis and orbicularis muscles. Insertion - It is inserted into the deep surface of the skin in the central part of the eyebrow Nerve Supply - T he temporal branches of the facial nerve. Function – Its contraction draws the medial portion of the eyebrow downwards and medially, creating vertical folds in the skin above the root of the nose, expressing frowning. > The pyramidalis: Origin - From the medial part of the frontalis I nsertion - Into the skin of the forehead. Nerve Supply - Branches of facial Nerve Function - Its action is to pull down the medial part of the eyebrow creating horizontal furrows over the bridge of the nose, which creates the expression of frowning.

6. Fig - Muscles of Eyebrow and Eyelid

7. Contd..

8. Fig- Cross-section eyebrow

9. Vessels and Nerves to eyebrows Blood supply - derived from the supraorbital and superficial temporal artery. Venous drainage - by the supraorbital, frontal, angular, and superficial temporal veins. Lymphatics - from the medial part drain into submaxillary lymph nodes, and from the lateral part drain into the parotid lymph nodes. Nerve Supply - Sensory nerve supply comes from the first division of the trigeminal nerve, through the frontal nerve. Motor nerve supply is through the temporal branch and buccal branch of the facial nerve.

10. Functions of eyebrows 1. Role in facial configuration Eyebrows form an important part of facial configuration and ornamentation. 2. Role in facial expression Eyebrows convey emotions - raised for fright, surprise, and pleasure, furrowed for deep thought, anger, or puzzlement. 3. 3. Protective functions of eyebrows Eyebrows and eyelids protect the eyes and surrounding area. Eyebrows shield the eyes from bright sunlight and prevent liquids on the forehead from running into the eyes. Supercilia are very sensitive to touch and help protect the eyes by providing an early warning system.. 4. Role of eyebrows in eyelid movements The eyebrow movements help in activating the upper eyelid in extreme upward gaze and when the levator is paretic. The eyebrows through maximum action of the frontalis help in some 3-5 mm additional elevation of the upper eyelids. The eyebrows also help in the forceful closure of the eyelids, by moving down.

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