The horse’s neck, stretching out to reach the bit, is a perception commonly associated with the lowering of the neck but the concept is in opposition of the muscular work actually achieved by the upper neck muscles when the neck is lowered.
“Men willingly believe what they wish.” (Gaius Julius Caesar)
Caesar’s thought applies to the lowering of the neck.
Creating a functional horse, athletically ready to perform, should definitively be the aim of all training techniques. But appropriate body coordination does not result from metaphors that envision the stretching or telescopic action of the neck.
These theories are fairytales. They mean well, in the sense that they wish to create a horse’s physique that functions effortlessly, but they are theorizing that the neck muscles work in a fashion that does not even come close to reality. The wishing of good things for the horse is a great emotion but when the relationship with the horse is based on athletic performance a sound understanding of how the horse truly functions, and for this article specifically how muscles of the upper neck work, is a prerequisite.
The main upper neck muscles are the splenius and semispinalis capitis. Both muscles are involved in the lifting of the neck and the resistance to its lowering. The head and neck weigh-in at about 10% of the horse’s body mass. This is a significant burden that is submitted to the attraction of gravity. Without the resistance of the upper neck muscles, the horse’s head would hang down only as far as the limit of compliance of the nuchal ligament.
This is what happens when a horse is under sedation; when the upper neck muscles no longer resist the attraction of gravity the nuchal ligament takes over the support. At its maximum elastic compliance, the nuchal ligament keeps the horse’s head a few inches above the ground. This is why horses separate their front legs to graze; so they can reach the ground.
Looking at the muscles’ basic architecture, the lack of single contractile units spanning from origin to insertion contradicts the theory that an action exerted at one end of the muscles would be transmitted to the other end.
This simplistic thinking often directs equestrian theories such as those that believe the lowering of the neck elongates the back muscles. Inside the muscle’s body, cells are producing forces that are transmitted to other cells via connective tissues and so on. Muscle cells can create simultaneous forces acting in different directions. Connective tissues are also arranged within the muscle, to permit simultaneous multiple tasks.
“Connective tissue division can facilitate neuromuscular compartmentalization for differential function along a long muscle.” 1
The morphology of the semispinalis capitis muscle implies different functions between its dorsal and ventral region. The muscle does have a strong central tendon within its body, which divides between the dorsal region situated above the tendon, and the ventral region situated below the tendon.
This type of different architecture between the dorsal and ventral part of the same muscle is often seen when the function of the muscle cells is to enhance the tension of the central tendon. When the neck is lowered, the central tendon stretches and the muscle cells work to increase the central tendon’s elastic resistance.
One needs to remember that the horse’s head weighs about 10% of the horse’s body mass. As the neck lowers, upper neck muscles, tendons and ligaments resist the burden of the head as it is pulled down by gravity.
A very simple experiment can be made, which requires a large bucket full of water, a broom and two bungee cords. The weight of the water bucket illustrates the weight of the horse’s head. The handle of the broom represents the column of the cervical vertebrae. One bungee cord represents the upper neck muscles. The other bungee cord is used to attach the water bucket on the tip of the broom handle. You attach one end of the bungee cord on the tip of the broom handle and hold the other end in your right or left hand. The bungee cord illustrates the central tendon of the semispinalis capitis and your arm acts like the muscle’s cells and connective tissues of the semispinalis capitis muscle. You block the base of the broom with your foot and pull on the bungee cord to lift the upper end of the broom and the water bucket.
Doing so, your arm is working as the horse’s upper neck splenius muscles work, as well as the dorsal element of the semispinalis capitis when they lift the horse’s neck. Then you lower the horse’s head, which in the experiment is the water bucket. According to the stretching theories, your arm should be stretching. Of course, it is not. You are pulling hard on the bungee cord otherwise the water bucket would crash onto the ground. So you are doing the work of the horse’s upper neck muscles. The lower you place the water bucket, the heavier is the pull on the central tendon, the bungee cord, and the stronger is the work of the muscle cells, which in the experiment are your arm’s muscles.
The thought that the horse’s neck telescopes out of the shoulders, stretches and reaches is wishful thinking to say the least. Even as a metaphor, the thought induces totally false ideas.
The problem is that a horse does not perform as a fictitious model. Athletic achievements involve muscles, tendons, ligaments, fascia, central pattern generators, and nervous circuits. If the body coordination matches the rider’s fantasy but is unrelated to the horse’s physiology, the horse performs below his potential until lameness shortens his career.
Lameness is not the only expression of physical pain, anticipation of a given movement or, more generally, anticipation of entering the show ring, worry, nervousness, gait abnormalities, frustration, anger, shutting off, and many other behaviors are expressions of pain.
The question might be; but why then does the horse lower the neck spontaneously after work? The response is simple. The horse eases the work of the upper neck muscles using the elastic resistance of the nuchal ligament. The nuchal ligament is inserted on the dorsal spines of the first through fourth thoracic vertebrae. At the other end, the funicular element of the nuchal ligament is attached on the skull. The nuchal ligament is not under tension when the neck is held in an alert position but does, in fact, come under tension when the horse lowers the neck.
The nuchal ligament, which can be compared to a strong bungee cord, elongates assisting the upper neck muscles in their task of supporting the head and neck. The nuchal ligament replaces 55% or more of the work of the upper neck muscles at the walk.
At the trot and canter, the assistance of the nuchal ligament replaces between 32 to 34% of the work of the upper neck muscles. As the horse lowers the neck, the tension of the nuchal ligament increases and the work of the upper neck muscles decreases.
This is not stretching; this is simply easing the work of the upper neck muscles.
The thought that the lowering of the neck increases the range of motion of the horse’s thoracolumbar spine is also inaccurate. Measurements have been made recording loss and gains in vertebral mobility when the neck is lowered.
The experiment involved five specimens. All the five specimens gained vertebral mobility between T6 and T9 when the neck was lowered. T6 and T9 is the front part of the withers. Such gain of mobility is mainly due to the fact that the supraspinous ligament, which is the continuation over the tip of the dorsal spines of the nuchal ligament, is still somewhat elastic until T9. One of the five specimens lost mobility between T9 and T14 when the neck was lowered. The other four specimens did not gain vertebral mobility in the same area, associated with the lowering of the neck. Another specimen lost vertebral mobility between T14 and T18 when the neck was lowered. The other specimens did not gain mobility in this specific area when the neck was lowered. All the specimens lost vertebral mobility in the lumbar vertebrae. The five specimens gained mobility in the lumbosacral junction. This is the reason why uneducated observations lead to the belief that the lumbar vertebrae flex when the neck is lowered.
During the 19th century, the Prussian cavalry promoted total elevation of the horse’s neck. The thought behind the theory was about improving the horse’s balance. The experiment lasted several decades and was then abandoned completely. My guess is that injuries reached an epidemic level and even the greatest supporters had to reconsider.
In contrast, Paul Plinzner, who was the Emperor’s riding master, lowered and over-flexed his horses’ neck completely. This was the end of the 19th century. Since then, the horse’s poll has either been held at the highest point of the neck, or at lowest point of the neck.
Whatever the fashion of the time was; going back and forth between both positions due to lack of proof of either being correct. Contemporary to Splinzner, François Baucher promoted the total elevation of the neck. Later Jacques Licart emphasized the extension of the neck. The French author had his mind set on stretching and referred to the lowering of the neck as an extension.
In fact, technically, the lowering of the neck is a flexion. The total elevation of the neck is an extension. More recently, Harry Bolt warned against working the horse’s neck too deep, and so on. The common denominator behind these contradictory theories is that they are based on little science and very large imagination. The other similarity is that while they are promoting diametrically opposed approaches, both theories pretend to engage the horse’s back as well as the hind legs.
The truth is that the effects attributed to the lowering of the neck cannot be achieved by acting on the neck. Neck postures are convenient short cuts promising results that are in fact the outcome of precise coordination of the horse’s physique, starting with the decelerating and propulsive activity of the hind legs and continuing with the capacity of the back muscles to convert the thrust generated by the hind legs into horizontal forces, forward movement, and vertical forces, resisting attraction of gravity and therefore balance control. Proper vertebral column mechanism allows the forelegs to propel the horse’s body upward and forward. The horse is then placing and using the neck to further enhance balance control and quality and accuracy of the limbs kinematics.
Pretending that such efficient coordination can result from the lowering of the neck is fiction. The problem is that fiction does not prepare efficiently the horse’s physique for the athletic demand of the performance.
References: Morphology, Histochemistry, and Function of Epaxial Cervical Musculature in the Horse. K. S. Gellman, J. E. A. Bertram, and J. W. Hermanson, Journal of Morphology 251: 182-194, 2002.