204 THE ANATOMY OF THE HORSE. 



The Submental Artery. This vessel, a branch of the submaxillary, 

 has already been seen in the dissection of the intermaxillary space. It 

 leaves the space by passing forwards through the mylo-hyoid muscle, 

 and extends along the posterior border of the sublingual gland, into 

 which and the muscles it throws branches. It extends beyond the 

 lower extremity of the gland, and terminates in small branches to the 

 mucous membrane. 



The Submental Vein. This is relatively larger than the artery, 

 which it accompanies. 



The Lingual Vein (Plate 30). This vessel will be found at the 

 upper part of the tongue, in company with the gustatory nerve. It 

 receives branches from the soft palate and pharynx, and joins the 

 buccal vein. 



The lingual artery (which runs its course separate from the vein of 

 the same name) and the 9th nerve cannot be followed until some of 

 the muscles have been dissected. Plate 31 will serve as a guide in the 

 isolation of these muscles. 



The Mylo-hyoid Muscle has already been seen in the dissection of 

 the intermaxillary space, and it is now seen on its opposite aspect. It 

 is described at page 176. 



The Stylo-glossus {Hyo-glossus longus of Percivall) (Plate 31). This 

 is a long, riband shaped muscle, arising by a thin aponeurotic tendon 

 from the outer surface of the great cornu of the hyoid bone near its 

 lower extremity. It extends along the side of the tongue to near its 

 tip, where its fibres are confounded on the middle line with those of the 

 opposite muscle. 



Action. — To retract the tongue, and at the same time to incline it 

 laterally if only one muscle acts. 



The Great Hyo-glossus {Hyo-glossus brevis of Percivall) (Plate 31). 

 To expose this muscle fully, the stylo-glossus should be cut near its 

 origin and reflected. The great hyo-glossus arises from the lateral 

 aspect of the glossal process, body, and thyroid cornu of the hyoid bone. 

 Its fibres extend obliquely forwards and downwards across the side of 

 the fixed portion of the tongue, and turn inwards on reaching the 

 dorsum. 



Action. — To retract and depress the tongue. 



Directions. — Incise the origin of the foregoing muscle, and raise it 

 forwards after the manner of Plate 32. This will expose more fully the 

 other muscles of the tongue, and also the lingual artery and the 9th 

 nerve. 



The Middle Hyo-glossus Muscle 1 (Plate 32) arises from the front of 

 the articulation between the great and the small cornu of the hyoid bone. 



1 This, apparently, is the muscle first described by Briihl, in 1850, as the middle 

 descend! a; 1 stylo-glossus. 



