Silmälihakset

Silmälihakset, also known as extraocular muscles, are a group of seven muscles located within and around the eyeball. Their primary function is to control the movement of the eye and maintain its position within the orbit. These muscles are responsible for the precise and rapid movements that allow us to scan our surroundings, focus on objects, and maintain binocular vision.

The six extrinsic eye muscles are responsible for moving the eyeball itself. These include the four rectus muscles: the superior rectus, inferior rectus, medial rectus, and lateral rectus. The superior rectus primarily elevates the eye, while the inferior rectus depresses it. The medial rectus adducts the eye (moves it inward), and the lateral rectus abducts it (moves it outward). Additionally, there are two oblique muscles: the superior oblique and the inferior oblique. The superior oblique depresses and externally rotates the eye, while the inferior oblique elevates and externally rotates it. Together, these six muscles allow for a wide range of eye movements in all directions.

The seventh muscle, the levator palpebrae superioris, is responsible for lifting the upper eyelid, allowing us to open our eyes. While not directly moving the eyeball, its function is crucial for vision by ensuring the field of vision is unobstructed.

All of these muscles are innervated by cranial nerves, primarily the oculomotor nerve (CN III), but also the trochlear nerve (CN IV) for the superior oblique and the abducens nerve (CN VI) for the lateral rectus. The coordinated action of these muscles, under precise neural control, is essential for clear and comfortable vision. Disruptions to the function of these muscles can lead to strabismus (crossed eyes), double vision, or difficulties with eye tracking.