Pathways of sympathetic innervation to the superior and inferior (Müller's) tarsal muscles.

Fluorescent staining and fluorescent microscopy were used to evaluate the pathways which the sympathetic nerves followed to reach the smooth muscles of the eyelids. Selected structures from fresh orbits were removed, sectioned, and fluorescently stained utilizing glyoxylic acid. Photographic results from the fresh orbits showed fluorescence accompanying the oculomotor, trochlear, and abducent nerves and branches of the ophthalmic division of the trigeminal (lacrimal, supraorbital, and nasociliary) nerves. The eyelids exhibited intense fluorescence within the tarsus and throughout adjacent connective tissue. The principal paths of the sympathetic nerves are the sensory (first dimension of the trigeminal) and the motor nerves to the orbit. The arteries (in contrast to previous descriptions) do not appear to be a major pathway.