THE SYMPATHETIC SYSTEM OF NERVES. 1367 



THE SACRAL PORTION OF THE GANGLIATED CORD. 



The sacral portion of the gangliated cord (pars pelvina systematis sympathetic!) 

 consists of four ganglia interconnected by association cords, there being a consider- 

 able degree of variation in both the number and the size of the ganglia (Fig. 1133). 

 Lying anterior to the sacrum and internal to the anterior sacral foramina, it is con- 

 nected above with the lumbar portion by a single or double association cord which 

 lies posterior to the common iliac artery, and below it gradually approaches the 

 median line and is united in front of the coccyx with its fellow of the opposite side by 

 a loop or fine plexus in which is situated the single coccygeal ganglion or gang- 

 lion impar. 



While this portion of the gangliated cord receives no white rami communicantes, 

 in the sense of trunks passing from the sacral spinal nerves to the sacral ganglia, the 

 visceral branches of the pudendal plexus pass directly to the pelvic plexus without 

 traversing ganglia, and are considered as being homologous with white rami. In 

 addition to these, white fibres reach the sacral from the lumbar portion of the 

 gangliated cord. 



The somatic branches are the gray rami communicantes. They arise from 

 the sacral ganglia and pass dorsally to join the anterior primary divisions of the sacral 

 and coccygeal spinal nerves. 



The visceral branches are distributed through the medium of the pelvic 

 plexus (page 1374) and furnish motor fibres to the longitudinal and inhibitory 

 fibres to the circular musculature of the rectum, the chief motor fibres to the bladder 

 (probably to the longitudinal muscular fibres), motor fibres to the uterus, the nervi 

 erigentes or vaso-dilators of the penis and secretory fibres to the prostate gland. 



Additional strands, the parietal branches unite and ramify, anterior to the 

 sacrum, with similar twigs from the opposite side and furnish filaments to the sacrum 

 and coccyx and their ligaments, and to the coccygeal body. 



THE PLEXUSES OF THE SYMPATHETIC NERVES. 



The tendency of the sympathetic nerves to form intricate and elaborate plexuses 

 (plexus sympathetici) is a marked feature of this portion of the nervous system. 

 They lie, in the main, anterior to the plane of the gangliated cord and consist of 

 fibres alone or of fibres and ganglia, from which smaller plexuses or branches pass 

 to the viscera. Some of them are of sufficient importance, size and individuality 

 to merit separate descriptions ; such are the cardiac, the pulmonary, the cesophageal, 

 the solar and the pelvic. The pulmonary and oesophageal plexuses have been 

 described in connection with the vagus nerve (page 1272). 



THE CARDIAC PLEXUS. 



The cardiac plexus (plexus cardiacus) consists of an interlacement of nerve-fibres, 

 containing one well-marked ganglion, to which accessions are brought by the vagus 

 and sympathetic nerves and from which fibres are furnished to the heart and, to a 

 slight degree, the lungs. It comprises two portions: (i) the superficial cardiac 

 plexus and (2) the deep cardiac plexus. 



1. The superficial cardiac plexus (Fig. 1135) is much the smaller of the 

 two and consists of a fine inosculation of nerve-fibres in the meshes of which is con- 

 tained a small ganglion, the ganglion of Wrisberg (g. cardiacum [Wrisbergi] ). 

 It is situated in the concavity of the arch of the aorta, between the obliterated ductus 

 arteriosus and the right pulmonary artery. Tributary to it are the superior cervical 

 cardiac branch of the left gangliated cord and the inferior cervical cardiac branch 

 of the left vagus, whilst its fibres of distribution contribute to (a) the right coronary 

 plexus, () the left half of the deep cardiac plexus and, along the left pulmonary 

 artery, (c) the left anterior pulmonary plexus. 



2. The deep cardiac plexus (Fig. 1135), considerably larger than the su- 

 perficial, is located above the bifurcation of the pulmonary artery, posterior to the 

 arch of the aorta and anterior to the lower end of the trachea. It comprises two 



