170 THE HORSE 



the back of the head, and is attached to the first four 

 bones of the neck, as well as to the great ligament already 

 mentioned. It has a reciprocal action on the neck and 

 shoulder, according to which is the fixed point at the time. 



A muscle which also assists the two mentioned in their 

 office is the complexus major, which forms the principal 

 portion of the lower part of the neck. It arises from the 

 transverse processes of the withers, and also from the five 

 lower bones of the neck, the fibres from which unite to form 

 one large muscle. It diminishes in size in the direction of 

 the head, finally terminating in a tendon inserted in the 

 occipital bone. 



Immediately below the splenius, and following the course 

 of the vein of the neck which is utilised for the operation 

 of bleeding, and which lies immediately below, is a most 

 important muscle, the levator humeri, or deltoides. It 

 extends from the back of the head and upper part of 

 the neck, and proceeds along the front of the shoulder 

 to the top of the fore-leg, and on the development and 

 power of this muscle many of the capabilities of the 

 horse depend. When the head is kept up by its own 

 proper muscles it becomes a fixed point from which the 

 levator humeri is enabled to raise the shoulder, so that 

 on the development of the four muscles, the splenius, the 

 levator anguli scapulae, the complexus major, and the levator 

 humeri, everything else must necessarily hinge. Any weak- 

 ness in any of these will absolutely prevent a horse from 

 sustaining prolonged exertion, however much he may excel 

 in other directions. 



Adjoining the levator humeri, but below it, and following 

 also the course of the vein which lies between the two 

 muscles, is the principal depressor of the head, the sterno- 

 maxillaris. 



It arises from the upper end of the sternum, or point of 

 the breast, covers the lower front of the neck, and is 

 inserted by a flat tendon into the posterior angle of the 

 lower jaw. It is not a very large muscle, for, when those 

 supporting the head and neck are relaxed, but little force 

 is required to pull the head down. 



