RESEARCH.
ORBICULARIS OCULI.
To squint and squeeze the eye shut is when we use the Orbicularis Oculi.
When it contracts, the eye, and often a much larger area of the face, including
the cheeks and the mouth, is affected. The orbicularis oculi is a
large oval-shaped muscle, encircling the eye and spreading into the cheek
beyond. The orbicularis oculi is very much like a large circle.
Made up of concentric circles, each one smaller than the last. The
outer circle represents the boundaries of the muscle, the lines within
it trace the paths of it's fibers. ( see fig 11 )
The fibers travel in upward and downward arcs from one end of the eye to
the other. All the fibers are fixed to the side of the bony nasal
bridge; their free ends are attached to the skin of the cheeks and at the
outer corner of the eye.
When the orbicularis contracts, the skin around the eye is pulled in toward
the nasal bridge. ( see fig 10 )
The eye begins to close, and the familiar 'crows feet' appear at the outer
eye corner. The more the fibers of the muscle shorten, the stronger
the contraction, and the smaller the oval around the eye gets. The
smaller it gets, the tighter the eye is closed and the more the skin wrinkles.
When the orbicularis is strongly contracted it also bulges up the cheeks,
the nasal folds, pulls on the corners of the mouth, and sometimes lowers
the brow.
Fig . 11 - The Orbicularis Oculi Muscle Fibers.
Fig . 10 - The Orbicularis Oculi in action.