Type III: MCG lying below ITA-‘low’ MCG
5.6. THORACIC CARDIAC NERVES
173 5.5.5. CERVICOTHORACIC CARDIAC NERVE
The CTCN arose from the CTG in this study from either the ICG or T1G component which concurred with Randall and Armour (1977) who termed the cardiac nerves from the CTG as cervicothoracic cardiac nerves. The CTCN was also found to send branches to the subclavian artery in all the specimens concurring with Standring et al. (2008). The CTCN branches arose by a single branch in this study differing widely with Kalsey et al.
(2000) who depicted the CTCN to give off 2-4 branches. The findings of this study compare favourably with Pather et al. (2006) in that the CTCN arose by a direct ganglionic branch from the CTG (100% vs. 83.7%, respectively). This study disagrees with Pather et al. (2006) in that the CTCN contributed to the DCP only as this study records CTCN contributing to the SCP in 4% of these specimens as well.
174 This study differs widely with Randall and Armour (1977) in that the cardiac plexuses do not receive any contributions from the thoracic sympathetic chain below the CTG as no branches exist below this point; however the findings of this study reflect contributions up to the level of T5 ganglion.
TABLE 26: RECORDED THORACIC LIMITS OF THORACIC CARDIAC NERVES
Author Year Composition Lowest thoracic limit (Ganglia)
Perman 1924 Adults T2
Ionesco and Enachescu 1928 Fetuses and adults T5 Kuntz and Morehouse 1930 Adult, young cadavers
and fetuses
T5
Saccomanno 1943 Adults T6/T7
Mitchell 1953 Adults T4
Ellison and Williams 1969 Fetuses T5
Mizeres 1972 Adults T4
Fukuyama 1982 ? T4-T5
Pather et al. 2003 Adults and fetuses T5/T6
Kawashima 2005 Adults T7
San Mauro et al. 2009 Adults T4-T5
De Gama (2010) 2010 Adults and fetuses T5
175 5.7. VAGUS NERVE
5.7.1.CERVICAL VAGAL CARDIAC NERVES
The cervical vagal cardiac branches were described in terms of superior, middle and inferior based on Mitchell‟s description (1953) differing from Mizeres (1972) who described it in terms of cervical and cervicothoracic branches. This study also differed from the nomenclature adopted by standard anatomical literature (Standring et al., 2008) and Kawashima (2005), who described these nerves as superior and inferior branches that arose from the vagus nerve and the RLN respectively.
The vagus nerve was found to contribute superior, middle and inferior cervical vagal cardiac rami in 19%, 34% and 69% of cases, respectively to the cardiac plexuses; these differed widely with the findings of Kawashima (2005) who described a 100% incidence ofboth the superior and inferior cardiac nerves. However, no middle vagal cardiac nerve was described in Kawashima‟s (2005) study.
5.7.2. THORACIC VAGAL CARDIAC NERVES
Kawashima (2005) described these nerves as arising from the vagus nerve when it curves to form the RLN. This study describes these branches as arising from the thoracic part of the vagus nerve based on Mitchell‟s description (1953).
Thoracic vagal cardiac rami were found in 48% of the specimens in this study; this differed from Kawashima‟s (2005) incidence of 77%. The thoracic vagal cardiac nervesin
176 this study ranged from 1-5 branches (Figure 24). These findings concur with Kawashima (2005) and Randall and Armour (1977).
5.7.3.RECURRENT LARYNGEAL CARDIAC NERVES
These nerves have been described as cervicothoracic branches of the vagus nerve by Mizeres (1972) and were found to contribute chiefly to the DCP on the right side (Kawashima, 2005). Mitchell (1953) described these nerves as those that arose from the RLN to reach the cardiac plexus while San Mauro et al. (2009) only described the nerves that arose below the origin of the RLN as inferior cardiac nerves. In this study these are described as branches that arise from the RLN and contribute to the cardiac plexuses as described by Mitchell (1953) thus reflecting the discrepancy that exists in the nomenclature in the literature reviewed. The incidence of these nerves in this study was 28% with a lower incidence on the left side (3%) corroborating the findings from Kawashima (2005), in that the right side had a higher contribution to the DCP.
The incidence of RLCN in the present study was 48%. This differed from the incidence of 100% reported by Kawashima (2005). The SCP received no contributions from the RLN in this study confirming reports by standard anatomical literature (Romanes, 1968;
Hollinshead, 1974; Standring et al., 2008). This study differs from the standard anatomical literature reviewed (Romanes, 1968; Hollinshead, 1974; Standring et al., 2008) as the RLN contributed 28 cardiac nerves to the DCP.
C C H H A A P P T T E E R R 6 6
CO C ON NC CL LU US S I I O O N N
178 6.1. CERVICAL SYMPATHETIC CHAIN
The course and relation of the cervical and thoracic sympathetic chains described in this study compare favourably with that reported in the current literature. This study records a single cervical sympathetic chain in 99% and a CSC made up of multiple branches in 1%
of the specimens. This study does not record any incidence of a double CSC; however it has been described in some of the literature reviewed.
CERVICAL GANGLIA
This study describes cervical ganglia that vary from two to five; this confirms the previous findings in the literature. This study also confirms the constant presence of SCG and reports an incidence of MCG that is favourable to previous descriptions in the literature reviewed. The vertebral ganglion is described as a separate ganglion that is not a detached portion of the MCG nor is it a low type of MCG. The incidences of the ICG and CTG were unfavourable to incidences described by the literature reviewed.