In an UMN lesion, called central seven, only the lower part of the face on the contralateral side will be affected, due to the bilateral control to the upper facial muscles ( frontalis and orbicularis oculi ).
42.
Outside the latter is a layer of striped muscle, continuous with the lacrimal part of the Orbicularis oculi; at the base of each lacrimal papilla, the muscular fibers are circularly arranged and form a kind of sphincter.
43.
Its superficial surface is covered by a fibrous expansion derived from the medial palpebral ligament, and its deep surface is crossed by the lacrimal part of the Orbicularis oculi, which is attached to the crest on the lacrimal bone.
44.
Ptosis associated with CPEO may be corrected with surgery to raise the lids, however due to weakness of the orbicularis oculi muscles, care must be taken not to raise the lids in excess causing an inability to close the lids.
45.
The orbicularis oris ( the sphincter muscle around the mouth ) is used in the playing of brass and woodwind instruments; as a result, players of these instruments tend to have a larger muscle around the mouth and may experience more discomfort during the piercing process.
46.
It arises from the medial end of the superciliary arch; and its fibers pass upward and laterally, between the palpebral and orbital portions of the orbicularis oculi muscle, and are inserted into the deep surface of the skin, above the middle of the orbital arch.
47.
The lacrimal part of the Orbicularis oculi draws the eyelids and the ends of the lacrimal canals medialward and compresses them against the surface of the globe of the eye, thus placing them in the most favorable situation for receiving the tears; it also compresses the lacrimal sac.
48.
Its medial fibers are continuous with those of the procerus; its immediate fibers blend with the corrugator and orbicularis oculi muscles, thus attached to the skin of the eyebrows; and its lateral fibers are also blended with the latter muscle over the zygomatic process of the frontal bone.
49.
Each time the eyelids are closed through the action of the Orbicularis, the medial palpebral ligament is tightened, the wall of the lacrimal sac is thus drawn lateralward and forward, so that a vacuum is made in it and the tears are sucked along the lacrimal canals into it.
50.
The fibers converge toward the angle of the mouth, where the central fibers intersect each other, those from below being continuous with the upper segment of the orbicularis oris, and those from above with the lower segment; the upper and lower fibers are continued forward into the corresponding lip without decussation.
