Raising the back

Some basic anatomy

 

The horses back is a bridge between the forehand and hindquarters. It is composed of many individual bones called vertebrae. The neck has 7 cervical vertebrae, these are connected to 18 thoracic vertebrae, followed by 6 lumbar, 5 fused sacral and around 20 tail vertebrae. The sacrum is an integral part of the pelvic girdle and it is this joint (the sacroiliac joint) that the vertebral bridge receives the entire thrust from the hindquarters which gets transferred over the back as forward movement.

 

All the vertebrae have prominent spinous processes which project upwards. The spines of the front half of the back point backwards and those of the back half point forwards. The tops of the spinous processes are connected by a tendinous ligament (the supraspinous ligament which becomes the nuchal ligament as it extends from the withers to the head. This is the upper brace of the vertebral bridge. The lower brace, running from the breastbone to the pelvic girdle is made up of a mass of tendons which fuse into the central linea alba.

 

The horses back is often likened to a suspension bridge with levers at both ends. The front lever is made up of the neck (the nuchal ligament and upper neck muscles) and these do the job of pulling the backwards facing spinous processes forward and thus raising the back.

 

 At the other end, muscles of the hindlimbs and the abdominal muscles working via the sacro-iliac joint, raise the back from behind by pulling on the spinous processes of the vertebrae further back which are oriented facing forwards.