Dominic Stone
The orbicularis oculi muscle, situated just beneath the skin of the eyelids, is responsible for closing the eyes. It is a sphincter-like muscle that extends from the medial to the lateral canthal region, enhancing the structural integrity of the eyelids. The muscle has three parts: palpebral, lacrimal, and orbital. The palpebral portion is responsible for the gentle closure of the eyelids, while the orbital part is involved in tight eyelid closure. The orbicularis oculi muscle is also associated with tear drainage and facial expressions.
| Characteristics | Values |
|---|---|
| Name of the muscle that closes the eyelids | Orbicularis oculi |
| Location | Just beneath the eyelid skin |
| Shape | Sphincter-like |
| Parts | Palpebral, lacrimal, orbital |
| Function | Closes the eyelids |
| Innervation | Cranial nerve VII (the facial nerve) |
| Blood supply | Branches of the internal and external carotid arteries |
| Pathology | Bell's palsy, blepharospasm |
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What You'll Learn
- The orbicularis oculi muscle is the primary muscle responsible for closing the eyelids
- The palpebral portion of the orbicularis oculi is involved in involuntary blinking and gentle eyelid closure
- The orbital portion of the orbicularis oculi facilitates voluntary forceful eyelid closure
- The levator palpebrae superioris muscle is responsible for opening the eyes
- The corrugator supercilii muscle works with the orbicularis oculi to shield the eyes from bright sunlight
The orbicularis oculi muscle is the primary muscle responsible for closing the eyelids
The orbicularis oculi muscle is a sphincter-like muscle that encircles the eyes and is located just under the eyelid skin. It is the primary muscle responsible for closing the eyelids. This muscle extends from the medial to the lateral canthal region, enhancing the eyelid's structural integrity and functionality. The orbicularis oculi muscle has three distinct parts: the palpebral, lacrimal, and orbital. The palpebral portion is further subdivided into the preseptal and pretarsal components. The orbital component forms a ring over the bony orbital margin and is recruited during forceful eye closure, as well as brow depression. The palpebral portion acts involuntarily, closing the eyelids gently during sleep or blinking. The orbital portion is subject to conscious control and is responsible for the voluntary closure of the eyelids.
The orbicularis oculi muscle is innervated by cranial nerve VII, also known as the facial nerve. The contraction of the palpebral portion closes the eyelid gently, and the palpebral orbicularis is the muscle of action in an involuntary blink and a voluntary wink. When the entire muscle is brought into action, the skin of the forehead, temple, and cheek is drawn toward the medial angle of the orbit, and the eyelids are firmly closed, as in photophobia. The skin thus drawn upon is thrown into folds, especially radiating from the lateral angle of the eyelids, forming the so-called "crow's feet".
The orbicularis oculi muscle is also involved in tear drainage. The lacrimal part of the muscle 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 favourable situation for receiving tears. It also compresses the lacrimal sac. This part is composed of two pieces: Horner's muscle and the muscle of Riolan, the latter of which helps hold the eyelids together to keep the lacrimal passage waterproof.
The orbicularis oculi muscle is the only muscle capable of closing the eye. Loss of function for any reason results in an inability to close the eye, requiring eye drops or, in extreme cases, surgical closure of the eye. The orbicularis oculi muscle is also important in ptosis and blepharoplasty surgery, as maintaining its function is critical to lid closure, blink, and corneal integrity.
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The palpebral portion of the orbicularis oculi is involved in involuntary blinking and gentle eyelid closure
The orbicularis oculi muscle is a sphincter-like muscle that is situated just beneath the skin of the eyelids. It is crucial in eyelid movement and extends from the medial to the lateral canthal region. The muscle is divided into orbital and palpebral sections, with the latter further subdivided into preseptal, pretarsal, and ciliary sections. The palpebral portion of the orbicularis oculi is responsible for involuntary blinking and gentle eyelid closure during sleep. This is because the palpebral portion acts involuntarily, closing the eyelids gently and involuntarily, as when we sleep or blink.
The preseptal and pretarsal parts of the palpebral orbicularis oculi contract during blinking or eyelid closure. This action also pulls the lacrimal sac laterally and forward, creating a vacuum that draws tears into the sac. The lacrimal part of the orbicularis oculi draws the eyelids and the ends of the lacrimal canals medialward, compressing them against the surface of the eye to receive tears. This part is made up of two pieces: Horner's muscle and the muscle of Riolan, which helps to hold the eyelids together to keep the lacrimal passage waterproof.
The palpebral portion of the orbicularis oculi is also involved in voluntary winking, with the relaxation of the levator muscle following the contraction of the palpebral portion. Involuntary blinking renews the precorneal tear film. A reflex blink is protective and may be triggered by a loud noise, corneal touch, or the sudden approach of an object. The orbital portion of the orbicularis oculi, on the other hand, is subject to conscious control and facilitates the voluntary, forceful closure of the eyelids.
The orbicularis oculi muscle is a facial expression muscle that aids in tear drainage and lymphatic drainage. It is also involved in various ocular reflexes such as frowning, squinting, and eye closure. The corrugator supercilii muscle works in combination with the orbicularis oculi to draw the eyebrows medially and downward to shield the eyes in bright sunlight when squinting. The lateral portion of the orbicularis oculi acts as a depressor to the lateral tail of the eyebrow, contributing to eye closure and the creation of "crow's feet" or lateral canthal lines.
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The orbital portion of the orbicularis oculi facilitates voluntary forceful eyelid closure
The eyelids are closed by the orbicularis oculi muscle, a sphincter-like muscle in the face that surrounds the orbit and extends into nearby regions of the head, including the eyelids, eyebrows, temporal and infraorbital regions. This muscle is critical to eyelid movement and is the only muscle capable of closing the eyelids. It also assists with tear drainage.
The orbicularis oculi muscle is divided into two sections: the orbital and palpebral sections, each further subdivided based on function. The orbital portion of the orbicularis oculi is subject to conscious control and facilitates the voluntary, forceful closure of the eyelids. This portion of the muscle is thicker and reddish in colour, with fibres that form a complete ellipse without interruption at the lateral palpebral commissure. The upper fibres of this portion blend with the frontalis and corrugator muscles.
The palpebral portion, on the other hand, acts involuntarily, closing the eyelids gently during sleep or when blinking. The palpebral portion can also be contracted actively and passively, and it is the muscle of action in an involuntary blink and a voluntary wink. The upper and lower sections of the palpebral fibres act as a depressor and an elevator, respectively.
The orbital and palpebral portions can work independently of each other, such as when the brows are furrowed by contraction of the orbital portion to reduce glare while the eyes are kept open by the relaxation of the palpebral portion. The contraction of the orbital portion of the orbicularis oculi results in a tight closure of the eye, with the areas surrounding the lids—the forehead, temple, and cheek—also involved in the contraction. This type of eyelid closure often serves as a protective mechanism against ocular pain or injury, known as reflex blepharospasm.
The orbicularis oculi muscle is innervated by cranial nerve VII (the facial nerve), and its function is essential for maintaining ocular health.
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The levator palpebrae superioris muscle is responsible for opening the eyes
The levator palpebrae superioris is innervated by the oculomotor nerve (cranial nerve III) and receives sympathetic nervous system innervation. It is supplied by the central caudal nucleus of the oculomotor complex. The oculomotor nerve projects crossed axons to the levator palpebrae superioris, allowing synchronous upper eyelid elevation during upward gaze.
The levator palpebrae superioris muscle is located in the superior eyelid and is responsible for maintaining the normal position of the upper eyelid. It is attached to the upper eyelid skin and the upper tarsal plate, with indirect extensions reaching the superior conjunctival fornix. The levator palpebrae superioris is associated with the Whitnall ligament and levator aponeurosis, which are important for the orbital pulley system.
The primary function of the levator palpebrae superioris muscle is to elevate the upper eyelid. This muscle is the only one capable of opening the eye. When this muscle is functioning properly, it is impossible to open a patient's eyelids when they resist. Injury or dysfunction of the levator palpebrae superioris or the oculomotor nerve can result in ptosis, or marked drooping of the upper eyelid.
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The corrugator supercilii muscle works with the orbicularis oculi to shield the eyes from bright sunlight
The orbicularis oculi muscle is responsible for closing the eyes. This muscle is located just beneath the skin of the eyelids and extends from the medial to the lateral canthal region. It has three distinct parts: the palpebral, lacrimal, and orbital. The palpebral portion is responsible for the gentle closure of the eyelids during sleep or blinking, while the orbital portion is subject to conscious control and facilitates the tight closure of the eyelids.
The corrugator supercilii muscle works in combination with the orbicularis oculi muscle to shield the eyes from bright sunlight. When an individual squints, these muscles draw the eyebrows medially and downward to create a roof over the middle of the forehead, protecting the eyes from excess sunlight. The action of squinting or frowning by the corrugator supercilii muscle is directly related to the development of static vertical wrinkles on the forehead.
The orbicularis oculi muscle is a sphincter-like muscle that surrounds the upper and lower eyelids. It is innervated by cranial nerve VII, also known as the facial nerve. The contraction of the palpebral portion leads to the gentle closure of the eyelids, while the contraction of the orbital portion results in a tight closure, often as a protective mechanism against ocular pain or injury.
In addition to its role in eyelid closure, the orbicularis oculi muscle assists in tear drainage. The lacrimal part of this muscle draws the eyelids and the ends of the lacrimal canals together, compressing them against the surface of the eye to facilitate tear drainage. The orbicularis oculi muscle is also involved in facial expressions and ocular reflexes, such as frowning, squinting, and winking.
The levator palpebrae superioris muscle, on the other hand, is responsible for opening the eye. It is part of the elevator muscle group and aids in elevating and lowering the upper eyelid. The superior tarsal muscle is also involved in the process of opening the eyelid, working in conjunction with the levator palpebrae superioris muscle.
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Frequently asked questions
The orbicularis oculi muscle.
It is a flat, broad, thin and wide muscle that encircles the eyes and is located just under the eyelid skin.
The muscle has three distinct parts: palpebral, lacrimal and orbital.
The palpebral part is responsible for gently closing the eyelids.
The orbital part is responsible for tightly closing the eyelids.
