øyelokkmuskler

The øyelokkmuskler, or eyelid muscles, are a group of muscles responsible for controlling the movement of the eyelids. These muscles are essential for various functions, including protecting the eye, blinking, and regulating the amount of light entering the eye.

The primary muscles involved are the orbicularis oculi and the levator palpebrae superioris. The orbicularis oculi is a sphincter muscle that encircles the eye and is responsible for closing the eyelid. It is divided into two parts: the palpebral part, which causes gentle closure for blinking, and the orbital part, which causes forceful closure, such as when squinting.

The levator palpebrae superioris is a muscle located in the upper orbit that acts to lift the upper eyelid, thus opening the eye. Its antagonist is the orbicularis oculi. Innervation for these muscles comes from cranial nerves. The orbicularis oculi is innervated by the facial nerve (cranial nerve VII), while the levator palpebrae superioris is innervated by the oculomotor nerve (cranial nerve III).

Disorders affecting these muscles can lead to various conditions. For instance, weakness or paralysis of the levator palpebrae superioris can result in ptosis, or drooping of the upper eyelid. Spasms of the orbicularis oculi can cause blepharospasm, characterized by involuntary forceful blinking or closure of the eyelids. These muscles work in coordination to ensure proper eye function and protection.