THE CERVICAL SYMPATHETIC <,'A.\(,'IJA 1007 



anastomose wit li brandies from the superior and middle cardiac nerves, and from the 

 inferior cervical ganglion, I Ims taking part in the format ion of the inferior thyreoid 

 plexus, from which liranclies pass to the thyreoid irland. 



(</) The middle cardiac nerve arises by one or more branches from the ganglion, 

 or from the trunk of the cord, and passes downwards behind the common carotid 

 artery and, on the right side, either in front of or behind the subclaviaii artery, and 

 t lien along the innominate artery to the deep part of the cardiac plexus (figs. 711) and 

 7'-0). It is frequently larger than the superior cardiac nerve. On the left side the 

 nerve runs between the .subclaviaii and common carotid arteries. On both sides the 

 qerve communicates with the inferior laryngeal nerveand theexternal laryngeal nerve. 



The middle cervical ganglion also gives branches to the common carotid plexus. 



THE INFERIOR CERVICAL GANGLION 



The inferior cervical ganglion is irregular in form. It is larger than the middle 

 cervical ganglion, and it lies deeply in the root of the neck behind the vertebral artery 

 or the first part of the subclavian artery, and in front of the interval between the trans- 

 verse processes of the last cervical and the first thoracic vertebra; (figs. 719 and 720). 

 It is connected with the middle cervical ganglion by the sympathetic trunk, and by 

 filaments passing to the ansa subclavia (Vieus-emi), and it is either blended direct ly 

 with the first thoracic ganglion or connected with it by a short stout portion of the 

 trunk. It gives rami to the last two cervical nerves and peripheral branches to the 

 vertebral and internal mammary arteries, to the heart, and to the inferior thyreoid 

 plexus. 



Connections. (1) The rami to the seventh and eighth cervical nerves are grey 

 rami communicantes. 



(2) The branches to the vertebral artery are large and they unite with similar 

 branches from the first thoracic ganglion to form a plexus, the vertebral plexus 

 (fig. 719), which accompanies the artery into the posterior fossa of the cranium, where 

 it is continued on the basilar artery. The plexus communicates in the neck by deli- 

 cate threads with the cervical spinal nerves. 



(3) The branches to the internal mammary artery form the internal mammary 

 plexus. 



(4) The inferior cardiac nerve may arise from the inferior cervical ganglion, 

 from the first thoracic ganglion, or by filaments from both these ganglia (figs. 719 and 

 720). It communicates with the recurrent laryngeal nerve and with the middle 

 cardiac nerve, and passes to the deep part of the cardiac plexus. On the left side 

 it frequently joins the middle cardiac nerve to form a common trunk. 



Construction of the cervical portion of the sympathetic trunk. This por- 

 tion of the trunk contains both medullated and non-medullated fibres, and a large 

 part of the former are of spinal origin. In the absence of white rami communi- 

 cantes to this portion of the sympathetic trunk, it is evident that few if any of the 

 spinal or efferent splanchnic fibres are contributed to it below the superior ganglion 

 by the cervical region of the spinal cord. Instead, such fibres are known to enter by 

 way of the white rami from the upper thoracic nerves, and to ascend to this portion of 

 the sympathetic trunk. Most of these fibres terminate about the cells of the supe- 

 rior, middle, and inferior cervical ganglia, and these cells in their turn give off 

 sympathetic fibres which pass byway of the communicating branches mentioned 

 above for the cephalic and cervical portions, to their distribution in the structures 

 of the head, neck, and thorax. The efferent splanchnic fibres which terminate in 

 the superior ganglion especially are among those which mediate (1) vaso-motor 

 impulses for the head; (2) secretory impulses for the submaxillary gland; (3) 

 pilo-motor impulses for the hairs of the face and neck; (4) motor impulses for the 

 smooth muscle of the eyelids and orbit, and (5) dilator impulses for the pupil. 

 The sympathetic or grey fibres in the cervical portion of the sympathetic trunk 

 arise from the cells of the upper thoracic and the cervical ganglia, and are passing 

 either to connect the ganglia with each other or to enter the peripheral branches 

 and proceed to their terminal distribution. 



