The attachments of the corrugator. The corrugator is actually two separate muscles, the procerus and the corrugator. They always contract together. The fan-shaped procerus attaches to the bone at the base of the nose (A), and to the skin at (B) between the eyebrows. The paired corrugators rise diagonally from their anchorage in the inner corner of the orbit (C) to their insertion in the skin above the middle of the eyebrow (D).
The corrugator pulls the brows down and together. It's active in most moods of distress and central to the expression of fear, sadness, and anger. It's also used unconsciously in talking or concentrating. The consequences of these uses is the eventual development of frown lines on the face. In the action of the corrugator, the eyebrow lowers, especially the inner third. It drops below the top of the upper lid. The eyebrows move closer together. A cashew-shaped lump appears at the inner end of the eyebrow, with a curved, vertical crease along its inside edge (A), the "frown line." A small, crescent-shaped dimple appears (B) above the middle of the eyebrow. This is where the muscle attaches to the skin and so becomes a low spot when the muscle contracts. A new, nearly horizontal fold appears above the eyelid (C). As the skin folds, it hides part of the upper lid, particularly the inner half. The inner end of the skin fold runs right into the descended inner corner of the eyebrow. The hollow created under it, at the inner corner, is in deep shadow (D). The downward pressure of the brow shoves the upper lid a bit lower, hiding more pf the iris.
The side view shows clearly the pulling downward and forward of the brow. Note also the lengthened and straightened skin fold (E) above the eye and the narrowing of the eye itself.
The frontalis muscle and corrugator muscle act directly on the brow and indirectly on the eye and its surroundings. Now well look at the two muscles, levator palpebrae and orbicularis oculi, that act directly on the eye and upper cheek and, sometimes, indirectly on the brow
The Eyelid Lifter: Levator Palpebrae
The upper lid is the more movable of our two eyelids because it has its own muscle: the levator palpebrae. It attaches to the skin of the upper lid on one end and to the roof of the eye socket on the other. When it contracts, the upper lid is lifted; the more contraction, the more lift—the more lift, the more wide open the eye.
Normally, the levator is slightly contracted, holding the upper lid in its awake position. When the levator begins to relax, the upper lid, pulled by
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