Each person has four pairs of recti muscles:
- Superior rectus muscle (Read more!)
- Inferior rectus muscle (Read more!)
- Medial rectus muscle (Read more!)
- Lateral rectus muscle (Read more!)
They all share a common origin, arising from a fibrous common tendinous ring known as the annulus of Zinn. It is located posteriorly at the apex of the orbit anterior to the optic canal.
From the ring, these muscles pass anteriorly in various directions along the walls of the bony orbit until they reach their insertion sites. The recti muscles end by attaching to the sclera of the eyeball at varying distances from the limbus. Overall, these muscles move the eyeball around its vertical and horizontal axis.
The name of these muscles is derived from Latin, and it means straight. The recti muscles have an entirely direct course from their origin to their attachment sites, and they do not show any turns or angles.