An investigation of the medial branches of the cervical and thoracic sympathetic chain.
The number of peripheral segmental branches of the cervical and thoracic sympathetic chains are more variable and larger than assumed by textbooks and literature (Groen et al., 1987). This investigation aims to clarify and update the variable patterns of the cervical sympathetic chain, the incidence of fused thoracic ganglia and the contributions of the cervical and thoracic sympathetic chain to the cardiac plexus. The study involved the macro and micro-dissection of 89 cadaveric sides (foetal, 60 and adult, 29). The gross anatomy of the cervical sympathetic chain and variations is documented. This study confirms previous reports that the number of ganglia in the cervical region ranged from 2 (absent MCG) to four (double MCG) ganglia. A double MCG was found in 25.9%. This study reports the higher incidence of the normal/typical MCG (as per textbook definition) i.e. Type II MCG (46.6%) than the Type I MCG (27.6%) and Type III (32.8%). The number of thoracic ganglia in this study is 8-11. Fusion of ganglia was found to be more common in the lower thoracic chain than in the upper thoracic chain. This study reports the origin of cardiac rami from the thoracic sympathetic chain up to the interganglionic segment between T5 and T6 ganglia. The incidence if TCR5 was 60.4%. In 15/58 sides (25.9 %) TCR5 arose from the interganglionic segment of the chain, either above or below the ganglion. An accurate knowledge of the anatomy of the sympathetic nervous system and the adjacent structures is, inescapably a definite asset to the procedures used in interrupting the neural mechanism (Jamieson et al.) 1952). Successful sympathetic denervation of the heart, a field often beset with failure, is dependant on adequate morphological knowledge. It is hoped that this study using human foetuses as well as adult cadaveric specimens will draw the attention to important variations that are relevant to the surgeon. The intricate anatomical relations presented in this study attest the complex anatomy of the sympathetic nervous system.