Numerical Aberrations of the Extraocular Muscles and the Levator Palpebrae Superioris: An Anatomical and Clinical Insight.

Purpose: To comprehensively review the literature about numerical aberrations of the orbital muscles of ocular motility (here referred to as extraocular muscles [EOMs]) and the levator palpebrae superioris (LPS).

Methods: The authors summarize the embryologic bases and the possible etiopathogenetic causes of numerical aberrations of the EOMs and the LPS and organize these lesions into several broad categories. The clinical and radiologic diagnostic challenges are discussed.