Cephalic Sympathetic Nerves

The cephalic sympathetic nerves have been adequately described anatomically. They are derived chiefly through the internal and external carotid and the vertebral nerves and plexuses. According to current concepts, the preganglionic fibers concerned are included in the thoracolumbar outflow and make synaptic connections predominantly in the cervical sympathetic trunk. Ganglia occur frequently in the internal carotid plexus.2,5,11A single small ganglion in the external carotid plexus near the origin of the facial artery has also been reported.10It has been assumed quite generally that preganglionic fibers reach these ganglia through rami that extend cephalad from the superior cervical sympathetic trunk ganglion and through the plexus on the common carotid artery. Adequate data relative to the frequency, size, and distribution of ganglia in the internal carotid nerve and plexus are wanting. According to Mitchell,12macroscopic ganglia occur only infrequently. He has observed microscopic ganglia at various levels along