17^ OUTLINES OF EQUINE ANATOMY. 



The jugular vein, after 2:>assing tlirougli the parotid 

 gland, receives the submaxillary vein when about opposite 

 -the thyroid body. It then proceeds down the channel of 

 the neck, receiving no important branches, until it arrives 

 at the lower part, when the superficial hrachial vein, which 

 carries blood from the fore extremity opens into it, and in 

 some cases it receives the lymph from the thoracic duct on 

 the left side, the great right lymphatic on the right (often, 

 however, this opens into the axillary vein) . Finally, be- 

 tween the two first ribs the jugulars unite to form the com- 

 mencement portion of the anterior vena cava. By removing 

 the jugular vein aud subscapulo-hyoideus we expose the 

 trachea, and on its supero -lateral part the carotid artery 

 with the pneumogastric and gangliated cord of the sympa- 

 -thetic nerves enclosed in its sheath, and the inferiof 

 laryngeal branch of the pneumogastric a little lower down. 



The (Esophagus is a long tube which commences an- 

 teriorly at the posterior part of the pharynx, and after 

 passing along the neck, and through the thorax, and the 

 foramen sinistrum of the diaphragm, terminates at the 

 cardiac or left opening of the stomach. At first situated 

 above the larynx in its course down the neck, it becomes 

 inclined to the left side (thus we watch the left side of the 

 neck to see a ball " go ") so that on entering the thorax it 

 is near the inner surface of the first left rib. While pass- 

 ing through the anterior mediastinum it becomes slightly 

 above the trachea inclined to the right side, and in pass- 

 ing over the base of the heart it crosses the right bronchus, 

 -then in the posterior mediastium, having rested in a special 

 groove in the left lung, where it is in company with the 

 •pneumogastrics, it passes with them through foramen 

 sinistrum. It consists of two coats. The external is mus- 

 cular, anteriorly it is directly continuous Avith crico-pharyn- 

 geus ; it consists of longitudinal fibres externally placed, 

 circular fibres internally, and until it has passed over the 

 base of the heart it retains its red colour, which is apt to 

 cause it to be mistaken for some of the cervical muscles in 

 the neck. Posteriorly it becomes thicker, and its fibres are 

 -continuous with those of the stomach. This coat is con- 

 nected to the internal or mucous coat by very loose areolar 

 'tissue, in consequence of which the latter is generally 

 arranged in longitudinal folds which close the cavity of 

 the tube. It is the termination of this mucous coat at the 



