Final answer:
While intrinsic muscles of the eye usually refer to the ciliary muscles and the iris sphincter and dilator muscles, this question may be requesting information about the extrinsic eye muscles which control eye movements. These extrinsic muscles include the superior, medial, inferior, and lateral rectus muscles as well as the superior and inferior oblique muscles.
Step-by-step explanation:
Intrinsic Eye Muscles
The question seems to refer to the intrinsic muscles of the eye, but from a biological perspective, the term usually refers to the extrinsic muscles of the eye, which are responsible for moving the eyeball. However, if we talk about intrinsic muscles, we should consider the muscles that are located within the structure of the eyeball itself, such as the ciliary muscles (which control lens shape for focusing) and the iris sphincter and dilator muscles (which control pupil size). For clarity, let's detail the functions of the extrinsic muscles, which are six in total.
The extrinsic eye muscles include the superior rectus, medial rectus, inferior rectus, lateral rectus, superior oblique, and inferior oblique. They control the movement of the eye up, down, medially, and laterally. For instance, the medial rectus muscle moves the eye inward towards the nose, while the lateral rectus muscle moves it outward. The superior and inferior rectus muscles are involved in moving the eye up and down. The superior and inferior oblique muscles provide rotational movement, allowing the eyeball to tilt and align properly with the visual axis when looking up or down.
The intrinsic muscles, particularly the ciliary muscle, play a crucial role in adjusting the shape of the lens for accommodation, allowing us to focus on objects at varying distances. Similarly, the iris sphincter and dilator muscles regulate the size of the pupil, dictating how much light enters the eye, essential for vision in different lighting conditions.