The oculosympathetic pathway is a neural pathway that controls the sympathetic nervous system's influence on the eye. It originates in the hypothalamus and travels down through the brainstem, then to the upper cervical spinal cord. From there, it ascends back up to the eye, influencing functions such as pupil dilation and eyelid elevation. This pathway is crucial for the body's response to stress and environmental changes. Damage or disruption to the oculosympathetic pathway can lead to conditions like Horner's syndrome, characterized by a constricted pupil, drooping eyelid, and lack of sweating on one side of the face.