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The orbicularis oculi muscle, situated just beneath the skin of the eyelids, is responsible for eyelid movement. This muscle is involved in facial expression, ocular protection and reflexes. It has three parts: palpebral, lacrimal and orbital. The palpebral part is responsible for the gentle closure of the eyelids, while the orbital part is responsible for the forceful closure of the eyelids. The lacrimal part is involved in the drainage of tears. The orbicularis oculi muscle is innervated by cranial nerve VII (the facial nerve).
| Characteristics | Values |
|---|---|
| Name of muscle that closes the eyelid | Orbicularis oculi |
| Location | Beneath the eyelid skin |
| Shape | Broad, flat, sphincter-like |
| Function | Closes the eyelid, drains tears, protects the eyes, aids in ocular reflexes and facial expressions |
| Parts | Orbital, palpebral, lacrimal |
| Innervation | Cranial nerve VII (the facial nerve) |
| Adverse effects | Skin folds at the lateral angle of the eyelids, wrinkles |
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What You'll Learn
The orbicularis oculi muscle is the eyelid closer
The orbicularis oculi muscle is a sphincter muscle of the eyelids, situated just beneath the eyelid skin. It is a broad and flat muscle, extending from the medial to the lateral canthal region. This muscle is divided into orbital and palpebral sections, each further subdivided based on function. The orbital portion of the orbicularis oculi primarily facilitates the voluntary, forceful closure of the eyelids. When the orbital portion contracts, the eye is closed tightly, and the areas surrounding the lids—the forehead, temple, and cheek—are involved in the contraction.
The preseptal and pretarsal parts of the palpebral orbicularis oculi contract during blinking or eyelid closure. Consequently, the small channels draining tears from the eye's surface to the lacrimal sac, called canaliculi, are compressed. The palpebral part can also involuntarily close the eyelids as a reflex mechanism. This protective action wipes the tears produced by the lacrimal gland across the surface of the eyeball, keeping it moist and free of potentially irritating particles. The fine control of the eyelids performed by the palpebral part also facilitates non-verbal communication and expression.
The orbicularis oculi muscle is innervated by cranial nerve VII (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. The levator palpebrae superioris muscle is responsible for elevating the upper eyelid and is part of the elevator muscle group. The orbicularis oculi muscle aids in the lymphatic drainage as well.
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It is a sphincter muscle with three parts
The orbicularis oculi muscle is a sphincter muscle of the eyelids, and it plays a vital role in eyelid movement and various ocular reflexes. This muscle is situated just beneath the eyelid skin and extends from the medial to the lateral canthal region. The orbicularis oculi muscle has three distinct parts: the palpebral, the lacrimal, and the orbital.
The palpebral part of the muscle originates from the superficial surface of the medial palpebral ligament, with muscle fibres composing the eyelids as they travel towards the lateral commissure of the eye. The superior and inferior fibres unite and insert into the lateral palpebral ligament. The palpebral part can be contracted actively and passively, and it is responsible for the gentle closure of the eyelids during blinking or sleeping. It also aids in tear drainage by pulling the lacrimal papillae medially and dilating the lacrimal sac.
The lacrimal part, also known as the deep palpebral part, originates from the lateral surface and lacrimal crest of the lacrimal bone. The fibres of this part course laterally, passing posteriorly to the lacrimal sac. The lacrimal part is involved in the drainage of tears.
The orbital part of the orbicularis oculi muscle is responsible for the forceful closure of the eyelids. Medially, this section attaches to the anterior limb of the medial canthal tendon and the surrounding periosteum. Laterally, it connects to the lateral palpebral raphe. The contraction of the orbital part draws the skin of the forehead and cheek towards the nose, contributing to ocular protection by limiting exposure to potential damaging factors such as bright light or blowing dust.
The orbicularis oculi muscle is innervated by cranial nerve VII, also known as the facial nerve. Understanding the anatomy and function of this muscle is essential in treating various eye and cosmetic conditions.
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The palpebral part is involved in tear drainage
The orbicularis oculi muscle is responsible for closing the eyelids. This muscle is located just beneath the skin and extends from the medial to the lateral canthal region. It is a sphincter muscle, which means it closes circumferentially. The orbicularis oculi muscle is divided into two sections: the orbital and palpebral sections, with the latter further subdivided into upper and lower sections. The upper section acts as a depressor, while the lower section acts as an elevator.
The palpebral part of the orbicularis oculi muscle is involved in tear drainage. This muscle interacts with the nasolacrimal duct system to facilitate tear drainage. The preseptal and pretarsal parts of the palpebral orbicularis oculi contract during blinking or eyelid closure, compressing the small channels that drain tears from the eye's surface to the lacrimal sac (called canaliculi). Simultaneously, the muscle pulls the lacrimal sac laterally and forward, creating a negative pressure that draws tears down the nasolacrimal duct toward the nasal cavity.
The lacrimal gland, or tear gland, is an almond-shaped exocrine gland located above the eyeball in the anterior part of the upper outer aspect of each orbit. It is responsible for secreting lacrimal fluid, or tear fluid, onto the surface of the eyeball. This fluid forms the aqueous portion of a multilayered tear film that lubricates, protects, and provides nutrients to the conjunctiva and cornea. The lacrimal gland consists of two parts: the larger orbital part and the smaller palpebral part. The palpebral part of the lacrimal gland lies below the levator palpebrae superioris aponeurosis and projects into the superolateral aspect of the upper eyelid, attaching to the superior conjunctival fornix.
The parasympathetic innervation to the lacrimal gland is a complex pathway that traverses through numerous structures in the head. This pathway involves both preganglionic and postganglionic parasympathetic neurons, which increase the secretion of lacrimal fluid from the lacrimal gland. The preganglionic parasympathetic neurons are located in the superior salivatory nucleus, with their axons exiting the brainstem as part of the facial nerve (CN VII). The lacrimal gland is drained by the superior ophthalmic vein into the cavernous sinus, with lymphatic drainage provided by the superficial parotid lymph nodes, which drain into the superior deep cervical nodes.
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The orbital part closes the eyelids tightly
The eyelids are controlled by the orbicularis oculi muscle, which is a sphincter muscle of the eyelids. This muscle is situated just beneath the eyelid skin and is critical in eyelid movement. It 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: palpebral, lacrimal, and orbital. The palpebral part can be contracted actively and passively. The upper portion acts as a depressor, and the lower portion acts as an elevator. The palpebral part can also involuntarily close the eyelids as a reflex mechanism. This protective action wipes the tears produced by the lacrimal gland across the surface of the eyeball, keeping it moist and free of potentially irritating particles.
The lacrimal part is involved in the drainage of tears. The preseptal and pretarsal parts of the palpebral orbicularis oculi contract during blinking or eyelid closure. Consequently, the small channels draining tears from the eye's surface to the lacrimal sac are compressed. The muscle's action simultaneously pulls the lacrimal sac laterally and forward, creating a negative pressure that draws tears into the nasal cavity.
The orbital part of the orbicularis oculi muscle closes the eyelids tightly. Contraction of the orbital part draws the skin of the forehead and cheek towards the nose, limiting exposure to potential damaging factors such as bright light or blowing dust. Such eyelid closure is often a protective mechanism against ocular pain or after injury, and is called reflex blepharospasm.
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The muscle is supplied by the facial nerve
The orbicularis oculi muscle is responsible for closing the eyelids. It is a broad, flat muscle that spreads into three regions and is situated just beneath the skin of the eyelids. It is a sphincter muscle, meaning that it closes circumferentially. The upper portion acts as a depressor, and the lower portion acts as an elevator.
The orbicularis oculi muscle is innervated by cranial nerve VII, also known as the facial nerve. This nerve is responsible for supplying motor neurons to the muscles of facial expression. The facial nerve has many functions, including providing special taste sensations to the anterior two-thirds of the tongue via the chorda tympani. It also supplies many of the glands of the head and neck, including the submandibular and sublingual salivary glands, the nasal, palatine, and pharyngeal mucous glands, and the lacrimal glands.
The facial nerve has several branches, including the zygomatic, buccal, and temporal branches, which supply the orbicularis oculi muscle. The zygomatic and buccal branches may also co-innervate the orbicularis and upper facial muscles. The temporal branch becomes superficial as it travels towards the lateral orbit and innervates additional muscles of facial expression. The zygomaticofacial nerve exits the orbit via the zygomaticofacial canal and supplies the lateral cheek and lateral lower eyelid.
The facial nerve plays a crucial role in eyelid function by innervating the orbicularis oculi muscle, which is responsible for eyelid closure. The contraction of the palpebral portion of this muscle leads to gentle eyelid closure, and it is involved in both involuntary blinks and voluntary winks. The orbital portion of the orbicularis oculi facilitates the voluntary, forceful closure of the eyelids. This muscle also aids in tear drainage by interacting with the nasolacrimal duct system.
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Frequently asked questions
The orbicularis oculi muscle, also known as the Horner muscle, is responsible for closing the eyelid.
The orbicularis oculi muscle has three distinct parts: the palpebral, lacrimal, and orbital.
The palpebral part of the orbicularis oculi muscle controls the eyelids, closing them gently and involuntarily as a reflex mechanism.
The orbital part of the orbicularis oculi muscle facilitates the forceful closure of the eyelids.
