A review on the functions of the horse back and longissimus dorsi muscle

Abstract

The function of a muscle is to permit movement and maintain posture. Such a key role depends on the interplay between its anatomical structure and the way is used during movement. From a mechanical sense, a muscle changes its length to generate force. If it generates force while shortening (concentric), it will generate mechanical power, and if it generates force whilst it is being stretched (eccentric), it will absorb mechanical power. The longissimus dorsi, the largest muscle of the horse's back, is of considerable importance for its key functions on the athletic ability and performance of the animal. In this review, I summarized the anatomy, functions, biomechanics, and disorders of the horse back. The biomechanics of the horse's back depend on the interaction between the spinal column and the spinal musculature. Especially, longissimus dorsi muscle performs different functions both along its length and different regions across each segment. Several studies have reported muscular disorders in the horse's back such as stiffness and limitation of motion range, as also by electromyography records on the muscle activity (albeit at single recording sites during locomotion). These reports are typically isolated observations and no study has yet integrated muscle activity patterns with the cycles of flexion-extension in any detail, neither a study has linked these factors to the muscle fascicle strains in the longissimus dorsi. Such studies will be fundamental to fully understand the mechanical role of the longissimus dorsi, particularly during locomotion, and will develop new treatment techniques for horse veterinarians. In addition, 3D anatomical measures of the structure in vivo integrated with measures of function back motion and longissimus dorsi muscle activity would be ideal to understand in further detail the function of the horse's back.