Variations in the formation of the cardiac plexus--a study in human foetuses

The origin and distribution of nerves forming the cardiac plexus and the subdivision of this plexus were studied in six human foetuses (2 male, 4 female) of gestational ages 30 to 40 weeks. The cardiac plexus was not divided into superficial and deep parts in any foetus. True plexiform arrangement of nerves forming the cardiac plexus was seen only after the nerves reached the walls of the heart. The sympathetic trunks, vagi, recurrent laryngeal nerves and phrenic nerves of both sides contributed to the cardiac plexus. The cervical sympathetic trunk showed only two ganglia bilaterally in one foetus; this has not been reported before. In one foetus on the right side, the middle cervical sympathetic cardiac branch joined the recurrent laryngeal and the phrenic nerves which has not been reported earlier. The sympathetic pathways to the heart were found to be very variable; no two foetuses showed the same arrangement. Awareness of these variations in the nerves forming the cardiac plexus would enhance the success of sympathectomy to augment cardiac blood flow or to relieve the severity of cardiac pain.