Nervous control of eyelid function. A review of clinical, experimental and pathological data

This review of the clinical and experimental literature on pre-motor eyelid control, including an analysis of available clinico-pathological reports, suggests support for the following hypotheses: (1) cortex, extrapyramidal motor systems and rostral brainstem structures contribute to the control of the levator palpebrae muscle (LP) in various eyelid functions; (2) though the LP motor nucleus is unpaired, the pre-motor control of LP is at least in part lateralized; (3) signals of the rostral interstitial nucleus of the medial longitudinal fasciculus (MLF) are involved in the control of coordinated lid movements with saccadic up- and downgaze movements; (4) lesions of the medial and/or principal portion of the nuclear complex of the posterior commissure are essential for the production of lid retraction. These structures are assumed to be involved in lid-eye coordination by providing inhibitory modulation of LP motor neuronal activity; (5) the ventral periaqueductal grey is assumed to play a role in the generation of tonic LP motor neuronal activity; (6) neurons of the caudal supraoculomotor area could play a role in the mediation of converging inhibitory inputs onto LP motor neurons.