THORAX AND ABDOMEN OF THE HORSE 



57 



ventral border of the trachea and medial to the scalenus muscle, and on 

 this side it is joined to the first thoracic ganglion by a short cord. On 

 the left, however, it is common to find the two ganglia so blended as to 

 make it impossible to distinguish them. The common ganglion so 

 formed lies within the first rib, lateral to the oesophagus and the longus 

 colli muscle. 



The irregularly quadrilateral first thoracic ganglion (ganglion 

 thoracale primum) lies within the first rib upon the longus colli muscle 



A. intercostalis suprema. 



! A. transversa colli. 



Second rib. 



A. cervicalis profunda. 

 / First thoracic nerve. 



M. longus colli. 



CEsophagus. 



N. vagus. 

 Cardiac nerves. 



Truncus costocervicalis. 

 Vena cava cranialis. 



First thoracic sympathetic ganglion. 

 Eighth cervical nerve. 



/ Rami communicantes of second 

 to seventh cervical nerves. 

 Seventh cervical nerve. 



~ A. vertebralis. 



N. phrenicus. 

 A. subclavia dextra. "' 



A. thoracica interna.' 



Trachea. 



N. recurrens. 



Sympathetic cord. 



^^i^^- N. vagus. 



-- A. carotis communis 



dextra. 

 " Caudal cervical ganglion. 



~ - V. jugularis dextra. 

 " Thoracic duct. 



^~ A. cervicalis ascendens. 

 ~~ A. transversa scapulse. 



A. thoracica externa. Truncus omocervicalis. 



Fig. 24. — The blood-vessels and nerves within the first three ribs of the right side. 



and trachea (right), or oesophagus (left), and between the vertebral and 

 deep cervical arteries. Joining the ganglion is a large nerve formed by 

 branches (rami communicantes) from the second to the seventh cervical 

 nerves inclusive. This accompanies the vertebral vessels, and therefore 

 traverses the various transverse foramina of the cervical vertebra*. 

 Communicating branches also connect the ganglion with the eighth 

 cervical and the first and second thoracic nerves. Cardiac nerves leave 

 the ganglion to join the cardiac plexus on the ventral surface of the 

 trachea. 



