Anteroposterior stability of eyeball is provided by all except:

Suspensory ligament of the eye ball The suspensory ligament (of Lockwood) is a pa of fascial sheath encasing the eye ball. It forms a hammock stretching below the eyeball between the medial and lateral check ligaments and enclosing the inferior rectus and inferior oblique muscles of the eye. The ligament suppos the eye, and prevents downward displacement of it. Gray's 40/e p658 writes- "A continuous fascial band, the suspensory ligament of the eye, is slung like a hammock below the eye, providing sufficient suppo such that, even when the maxilla (forming the floor of the orbit) is removed, the eye will retain its position."