Orbicularis oculi muscle

Orbicularis Oculi Muscle

Anatomy of the orbicularis oculi muscle

The orbicularis oculi muscle is a complex, circular muscle located in the face, primarily responsible for the movement of the eyelids. It plays a crucial role in facial expression and the protection of the eyes.

Anatomy

The orbicularis oculi muscle is a sphincter muscle that encircles the eye. It is divided into three distinct parts:

• Orbital part: This portion surrounds the bony orbit and is responsible for the forceful closure of the eyelids.
• Palpebral part: Located within the eyelids, this part facilitates gentle closure, such as blinking.
• Lacrimal part: Also known as the tensor tarsi, this part is involved in the drainage of tears by compressing the lacrimal sac.

Function

The primary function of the orbicularis oculi muscle is to close the eyelids. It is essential for:

• Blinking: Protects the eye from foreign bodies and helps spread tears across the surface of the eye.
• Winking: A voluntary action that involves the contraction of the muscle.
• Tear drainage: Assists in the movement of tears through the lacrimal apparatus.

Innervation

The orbicularis oculi muscle is innervated by the facial nerve (cranial nerve VII). The temporal and zygomatic branches of the facial nerve supply the muscle, allowing for its various functions.

Clinical Significance

Dysfunction of the orbicularis oculi muscle can lead to several clinical conditions, including:

• Lagophthalmos: Inability to close the eyelids completely, often due to facial nerve paralysis.
• Blepharospasm: Involuntary, forceful closure of the eyelids, which can be a symptom of various neurological disorders.

Related Muscles

The orbicularis oculi muscle works in conjunction with other facial muscles, such as the levator palpebrae superioris and the corrugator supercilii, to facilitate complex facial expressions and eye movements.

Related Pages

• Facial nerve
• Facial muscles
• Eyelid
• Tear film