HEAD AND NECK OF THE HORSE 29 



The long abductor arises from the ligamentmn nuchoe and is 

 inserted into the posterior and lateral part of the conchal cartilage 

 below the level of the incisura intertragica. 



The short abductor lies beneath tlie long muscle, in common with 

 which it arises from the ligamentum nuchte. It is inserted into the 

 conchal cartilage close to the base of its styloid process. 



Mm. auriculares swperiores. — The superior group of muscles 



includes a short and a middle levator. The short levator is narrow and 



arises from the surface of the scutular cartilage. It crosses obliquely 



underneath one of the anterior auricular muscles (the fourth as 



described above) to be inserted into the medial surface of the conchal 



cartilage. The middle levator lies under cover of the interscutular and 



long levator muscles. Its origin is from the external sagittal crest, and 



its insertion is into the medial surface of the conchal cartilage. 



Dissection. — Reflect the middle levator and tlie long abductor 

 muscles. 



Mm. auricidares profundi. — The deep auricular muscles are 

 rotators — long and short — which cross each other and pass from the 

 deep surface of the scutular cartilage to the concha. 



M. tragicus. — To expose this muscle a considerable volume of fat in 

 the recfion of the conchal cartilage must be removed. The muscle is 

 small and narrow. Its origin is from the posterior aspect of the bony 

 wall of the external acoustic meatus and the annular cartilage, and its 

 insertion is into the basal part of the conchal cartilage. 



Intrinsic muscles. — Three very rudimentary and unimportant 

 intrinsic muscles are described. M. antitragicus lies on the conchal 

 cartilage close to the point at which its free borders meet. M. helicis 

 occupies a similar level on the anterior border of the cartilage and 

 extends into the hollow between the crura helicis. The two foregoing 

 muscles are partly continuous with the inferior auricular muscle. 

 M. verticcdis auriculce consists of a few muscular and tendinous 

 bundles on the convex surface of the conchal cartilage. 



The arteries of the ear. — Only the terminal part of the vessels that 

 furnish blood to the external ear can be examined at the present stage 

 of the dissection. Their origin and an appreciable part of their course 

 are hidden by the parotid gland. 



A. auric Lilaris posterior. — The main artery of the external ear is 

 the posterior auricular, a branch of the external carotid. Beginning on 

 a level with the great cornu of the hyoid bone, this artery runs under 

 the parotid gland to the base of the ear, but its origin and the first part 

 of its course must not be sought at present. Those branches of the 

 artery that supply the ear are as follows : — 



