The orbicularis oculi is a muscle found in the face and used to close the eyelids. The orbicularis oculi is made up of skeletal muscle fibers, and is receptive to nerve originating from the facial area. It is a significant muscle used for facial expression. It is located directly underneath surface of skin encircling the eyes and aids in closing of eyelid. It can also help in draining and passing of tears through parts such as lacrimal sac, canaliculi, and punctum— constituents of the tear drainage system. That is why you see you are able to control the release of tears. This muscle is made up of mainly three parts and they are the orbital portion, palpebral portion, and lacrimal portion.
Orbicularis Oculi Muscle – Anatomy (Origin and Insertion)
This muscle emerges in the nasal areas of the front bone specially in the nasal process or frontal process of maxilla. After the fibers originate from this part, they take a lateralward direction and form a wide and slender layer of muscles occupying the palpabrae or eyelids. That layer of muscles also surrounds the perimeter or borders of orbit.
The muscles again spread over to temple before they stretch downward on the cheek. The palpebral area of these muscles appears pale and thin, and it originates from the divergence of medial palpebral ligament. It then makes a series of concentric curves before inserting into a tapered fibrous band called the lateral palpebral raphe, which is located at the outer canthus or corner of eye.
Another section of the muscle is orbital part, which appears thicker and reddish in color. The fibers of this muscle tend to form a whole ellipse with no interruptions at lateral palpebral commissure. On the upper areas of orbital parts blend with other parts like the corrugators and the frontalis.
Another part of the fibers is the lacrimal section or the tensor tarsi, which is a tiny emaciated muscle, which has a width of approximately 6 mm and extends 12 mm. This is positioned at the rear of ligaments called medial palpebral, as well as the lacrimal sac.
The lacrimal section starts at posterior crest and passes at the rear of lacrimal sac before dividing into two slips of muscles to form the lower and upper muscles that insert into inferior and superior parts of the tarsi medial.
Orbicularis Oculi – Function
The orbicularis oculi muscle acts to aid in keeping the eye shut. It is the only muscle, which has the ability to close the eye. Where there is loss of function of this muscle for any reason, it may result in inability of one to be able to close their eye, and this may necessitate the use of eye drops to relax the muscles or in major cases, it may lead to removal of the eye.
Damage to orbicularis oculi may cause complications
Examining the function of orbicularis oculi is important because if there is a problem that affects the muscle, and it is left unchecked, it could result in conditions like lagophthalmos where there is complete failure of closing of eyes or a condition like paralytic ectropion, which refers to eversion of lower eyelid. A patient’s ability to close the eyelids is usually examined by doing an instructing procedure to tell the patient to close his or her eyes as the practitioner observes or counters the action.
There is need also for the eyelid position and cornea to be checked whenever there are issues that affect the orbicularis oculi muscles. The doctor may instruct a patient to close their eyes gently and tightly so as to examine the severity of the muscle damage. To tone of the muscles may also be examined this way where the practitioner counters the action of closing the eyes.
When something enters your eyes, you blink immediately. This is because there are nerves, which stimulate the action of blinking or blinking reflux in eyes. The initiation of the blinking usually involves activation of facial nerve motor function, which prompts the orbicularis oculi, especially the palpebral part to be able to contract thereby closing the eyes.
Doctors may also test the functioning of the blink reflex to determine whether the muscle is working properly. They do this by wisping cotton on eyes and if you do not blink, it could mean that there is problem with the facial nerves, which are responsible for sending messages to the muscles to close the eye.
When there is damage to the facial nerve, it may result in paralysis of one side of face since the muscles, which help in facial expression, are affected. This may lead to a condition known as Bell’s palsy where a patient is unable to close the eyes and move the side that is affected. A patient with Bell’s palsy develops drooping of eyelid or ptosis— and the signs may mimic those of stroke.
The closure of eyes prevents damage that could occur to cornea. When a patient has Bell’s palsy, it may result in corneal dehydration as well as ulceration, and therefore, proper care is needed. A disease called myasthenia gravis may affect the neuromuscular junction, whereby it causes the muscles to paralyze. A patient may be able to close the eye but it does not take long, and the orbicularis oculi will get tired and the eye is exposed. Orbicularis oculi exercises can help in relaxing and toning the muscles that close they eyes.