Oculosympathetic Motor System Dysfunction
During the active awake state, the muscle of Müller helps to keep the upper and lower eyelids apart. This muscle is innervated by the oculosympathetic system. The oculosympathetic system is a 3-neuron system. The first group of neurons are in the posterior hypothalamus (Figure 186.1 [1]). The first group of neurons are in the posterior hypothalamus (Figure 186.1[1]). The second group of neurons are at the Budge ciliospinal center (Figure 186.1 [2]). The third group of neurons, those that innervate the muscle of Müller, are at the superior cervical ganglion (Figure 186.1 [3]). The fibers from the sympathetic neurons in the posterior hypothalamus form the central sympathetic tract. This tract travels caudally in the brainstem and the rostral cervical spinal cord until it reaches the spinal cord segments C8 and T1.

Figure 186.1.— Oculosympathetic pathway. MM: muscle of Müller; CS: cavernous sinus; ECA: external carotid artery; ICA: internal carotid artery; CCA: common carotid artery; BP: brachial plexus; T1: thoracic 1 spinal segment; C8: cervical 8 spinal segment; BCSC: Budge ciliospinal center; CST: central sympathetic tract; A: common site of injury.