134 THE SURGICAL ANATOMY OF THE HORSE 



The Collateral Branches of the External Carotid are : 



A. The submaxillary artery^ which is a very large branch running 

 downwards across the subscapulo-hyoideus muscle. It next places 

 itself in company with the submaxillary vein and Stenson's Duct, 

 and these three structures run forwards along the intermaxillary 

 space. They curve round the inferior border of the horizontal 

 ramus, and the subsequent course of the artery has already been seen 

 in our description of the Duct of Stenson. After leaving the duct, 

 the artery continues its course across the buccinator muscle, passes 

 under the zygomaticus, and ultimately divides into the afigular 

 and nasal arteries. 



Collateral Branches of the Submaxillary Artery. 



(i) The pharyngeal artery, which is distributed to the pharynx, 

 from whence it is continued as a long slender vessel to assist in 

 the supply of the soft palate. 



(2) The lingual artery. — This branch passes under the great 

 hyo-glossus muscle and across the small cornu of the hyoid bone. 

 It then runs downwards beneath the middle hyo-glossus and palato- 

 glossus muscles to enter the tongue. In the tongue it has a 

 very tortuous disposition, and it runs forwards to the tip where it 

 anastomoses with the corresponding artery of the opposite side. 



(3) The submental artery. — This is a much smaller vessel, and it 

 takes a course along the inferior belly of the digastricus muscle 

 to gain the superior face of the mylo-hyoid. It subsequently 

 pierces this latter muscle and is distributed to the parts beneath it. 



(4) The inferior labial artery. — This branch passes along the outer 

 surface of the inferior maxillary bone, and it takes a course beneath 

 the depressor labii inferioris muscle, to be distributed to the lower 

 lip. It anastomoses with the mental branch of the inferior dental 

 artery, which comes out through the mental foramen. 



(5) The superior labial artery passes forwards across the buccinator 



