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Muscles surrounding the fissure
Last reviewed: 23.04.2024
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The eye slit is surrounded by bundles of the circular eye muscle, in which several parts are prominent.
The circular muscle of the eye (m.orbicularis oculi) is flat, occupies the periphery of the orbit circumference, is located in the thickness of the eyelids, partially enters the temporal region. Lower tufts of muscle continue into the cheek area. The musculature consists of 3 parts: age-old, ocular and lachrymal.
The secular part (pars palpebralis) is represented by a thin layer of muscle bundles, which begin on the medial ligament of the eyelid and adjacent areas of the orbital wall of the orbit. Muscular bundles of the secular part pass along the front surface of the cartilages of the upper and lower eyelids to the lateral corner of the eye; here the fibers intertwine, forming the lateral seam of the century. Part of the fibers is attached to the periosteum of the orbital wall of the orbit.
The glabellar part (pars orbitalis) is much thicker and wider than the age-old part. It starts on the forehead of the frontal bone, on the frontal process of the upper jaw and the medial ligament of the eyelid. The tufts of this muscle go to the outside until the lateral wall of the orbit where the upper and lower parts continue into each other. In the upper part weave the bunches of the frontal abdomen of the occipital-frontal muscle and the muscle wrinkling the eyebrow.
The lacrimal part (pars lacrimalis) begins on the tear ridge and the adjacent part of the lateral surface of the tear bone. The lacrimal fibers pass laterally behind the lacrimal sac and are weaved into the wall of this sac and into the age-old part of the circular muscle of the eye.
Function: the circular muscle of the eye is the sphincter of the eye gap. The secular part closes the eyelids. With the reduction of the ophthalmic part on the skin in the eye area, folds are formed. The greatest amount of fan-shaped divergent folds is observed from the outer corner of the eye. This same part of the muscle shifts the eyebrow down, while simultaneously pulling the cheek skin upward. The lacrimal part expands the lacrimal sac, regulating the outflow of tear fluid through the nasolacrimal duct.
Innervation: facial nerve (VII).
Blood supply: facial, superficial temporal, supraorbital and infraorbital arteries.
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