56 THE SURGICAL ANATOMY OF THE HORSE 



the pes anserinus. These nerves pass between the gland and the bone 

 immediately below the condyle of the inferior maxilla, and here also the 

 transverse facial artery with its accompanying vein passes. Much nearer 

 the inferior extremity of this border the outer terminal division of the 

 maxillo-muscular artery makes its appearance, and runs forwards 

 embedded in the masseter muscle. The transverse ficial artery is 

 much more superficially placed than is this division of the maxillo- 

 muscular. 



The posterior border of the gland is curved, with the concavity of the 

 curve directed upwards and backwards. It is loosely attached to the 

 outer border of the wing of the atlas. 



The superior border is also curved, and encircles the base of the 

 conchal cartilage. 



The inferior border is almost straight, and along it runs the sub- 

 maxillary vein, which takes a course backwards to unite with the jugular 

 vein, just before the latter vessel leaves the gland at its postero-inferior 

 angle. 



The parotid gland derives its blood-supply from the collateral twigs 

 of the vessels which it covers, namely, the external carotid artery and 

 its terminal branches. The nerve-supply of the gland comes from 

 the seventh, and the inferior maxillary division of the fifth nerve. 



Diseases of the Parotid Gland 



'External Injury. — Owing to the superficial position of this gland 

 it is very liable to external injury, such as wounds, bruises, etc. 

 Such injuries are most serious when affecting the posterior half or 

 an area of about two inches above its inferior border, since in these 

 positions the vessels and nerves already described are very frequently 

 involved in the injury. Towards the centre of the gland there is 

 much less risk, for the jugular vein is here deeply seated within 

 the substance of the gland. 



