Figure 6. Sympathetic pathway to the head. Note the descending connection from the hypothalamus through the brain stem and cervical spinal cord to the pregangilionic neuron in the upper thoracic cord. The axon from the preganglionic neuron exits the cord and joins the sympathetic gangliated chain. Those destined for the head ascend the cervical sympathetic chain to reach the superior cervical ganglion, where they synapse with postganglionic neurons. The axons from the postganglionic neurons join blood vessels to the head (those to the orbit are depicted in the figure as following the internal carotid to the ophthalmic artery. With permission from A.G. Reeves, "Disorders of the Nervous System."