MIDDLE AXD LOTVER CERVICAL GANGLIA. 633 



On the left side, the middle cardiac nerve enters the chest between 

 the left carotid and subclavian arteries, and joins the left side of the 

 deep cardiac plexus. 



AVhen the middle cervical ganglion is small, the middle cardiac nerve may be 

 found to be an offset of the iater-ganglionic cord. 



LOWER CERVICAL GANGLION. 



The lower or third cervical ganglion is irregular in shape, usually 

 somewhat flattened and round or semilunar, and is frequently united in 

 part to the first thoracic ganglion. Placed in a hollow between the 

 transverse process of the last cervical vertebra and the neck of the first 

 rib, it is concealed by the vertebral artery. It is connected by short 

 communicating cords with the two lowest cervical nerves. Numerous 

 branches are given off from it, among which the largest is the lower 

 cardiac nerve. 



The lower cardiac nerve, issuing fi'om the third cervical ganglion 

 or from the first thoracic, inclines inwards on the right side, behind the 

 subclavian artery, and terminates in the cardiac plexus behind the arch 

 of the aorta. It communicates with the middle cardiac and recurrent 

 laryngeal nerves behind the subclavian artery. 



On the lift side, the lower cardiac often becomes blended with the 

 middle cardiac nerve, and the cord resulting from their union terminates 

 in the deep cardiac plexus. 



Branches to blood-vessels. — From the lowest cervical and first 

 dorsal ganglia a few slender branches ascend along the vertebral artery 

 in its osseous canal, forming a plexus round the vessel by their inter- 

 communications, and supplying it with offsets. This plexus is connected 

 with the cervical spinal nerves as far upwards as the fourth. 



One or two branches frequently pass from the lower cervical ganglion 

 to the first dorsal ganglion in front of the subclavian artery, forming 

 loops round the vessel (ansa3 Yieussenii), and supplying it with small 

 offsets. 



THORACIC PART OF THE GANGLIATED CORD. 



In the thorax the gangliated cord is placed towards the side of the 

 spinal column, in a line passing over the heads of the ribs. It is 

 covered by the pleura, and crosses the intercostal blood-vessels. 



Opposite the head of each rib the cord usually presents a ganglion, 

 so that there are commonly twelve of these ; but, from the occasional 

 coalescence of two, the number varies slightly. The first ganglion when 

 distinct is larger than the rest, and is of an elongated form ; but it is 

 often blended with the lower cervical ganglion. The rest are small, 

 generally oval, but very various in form. 



Connection u'ith the sjmufl nerves. — The branches of connection be- 

 tween the spinal nerves and the ganglia of the sympathetic are usually 

 two in number for each ganglion ; one of these generally resembling 

 the spinal nerve in structure, the other more similar to the sympathetic 

 nerve. 



BRANCHES OF THE GANGLIA. 



The branches furnished by the first five or six gangaa are small, and 

 are distributed in a great measure 'to the thoracic aorta, the vertebrae., 



