Muscle · Head

Medial rectus

Musculus rectus medialis

The thickest and strongest of the four straight eye muscles, running along the inner wall of the socket to turn the eye toward the nose. It is one of only two extraocular muscles with a single pure action — the other is the lateral rectus opposite it — because its line of pull lies in the same plane as the movement it produces, so everything it does is adduction, with no vertical or rotational component. That makes it the workhorse of convergence: the two medial recti acting together are what aim both eyes at something close to your face when you read or thread a needle.