Equine Anatomy Relative to Saddle Fit
Proper saddle fit can basically be defined as damage control. I have seen horses suffering with back pain, muscle atrophy, arthritis, ulcers, kissing spines, sore feet, hock and stifle lameness and other undiagnosed issues. I think by understanding a little bit about the anatomy of the horse, it will be easier to understand why the saddle fit is so important.
Although my focus is on the saddle support area, it is important to note that poor fitting saddles do damage to other areas of the horse, not just the saddle support area.
Breaking it down to 3 parts, I will explain how the saddle should fit to avoid damaging the bones, muscles and the ligaments in the front, middle and rear of the saddle support area.
1. The Front of the Saddle Support Area including:
o Thoracic Vertebrae
o Trapezius Muscle
o Nuchal and Supraspinous Ligaments
2. The Middle of the Saddle Support Area including:
o Thoracic Vertebrae
o Longissimus and Latissimus Muscles
o Supraspinous Ligaments
3. The Back of the Saddle Support Area
o Lumbar Vertebrae
o Gluteus Muscle and Latissimus Muscles
o Supraspinous Ligaments
The front of the saddle support area gets a lot of attention because there is a lot going on there. Starting with the bones, the scapula rotates upwards and backwards along the sides of the withers usually about a hands width. At the top of the scapula is a very delicate cartilage that acts as a lubricant to allow the bone to slide gently through the muscles. The cartilage can easily be damaged between the large strong scapula bone and the steel or wooden tree of a saddle that is girthed up tight carrying a rider 150+ lbs. Cartilage does not regenerate so damaging it is permanent.
To prevent cartilage damage and to allow the horse shoulder movement freedom, the angle of the tree must match the angle of the shoulder. The tree width must also be wide enough to allow the shoulder to pass through under the front of the saddle. Typically we look for 3 fingers on the top as well as the sides of the withers to give plenty of room for the shoulder rotation and you should be able to slide your hand down under the front of your saddle simulating the shoulder movement.
The highest thoracic vertebrae are known as the withers. Over top of the withers is the trapezius muscle. The trapezius muscle moves the scapula. Pinching on the sides of the withers activates the spinal thoracic nerves in the trapezius causing a reflex reaction of hollowing the back, raising the head and rotating the pelvis. The trapezius can atrophy or change shape from riding in a saddle that pinches at the withers resulting in large shoulder holes, white hairs and an L Dip in front of the withers. If you are having trouble getting your horse to round his back, engage his hindquarters or stretch forward, it may be because your saddle is pinching his withers.
The nuchal ligament goes from the poll to the withers where it meets the supraspinous ligament which goes to the sacrum. This ligament system basically connects all the vertebrae together and acts as a suspension bridge for the skeleton. If the saddle does not allow room for the ligament, it cannot do it’s job, resulting in physical damage to the horse.
The middle of the saddle support area consists of the thoracic vertebrae, the supraspinous ligament that holds them together on top and the longissimus and latissimus muscles. The supraspinous ligament attaches to the nuchal ligament at the withers and runs along the top of the horses back to the sacrum.
The ligament basically holds the horse together so that the muscles don’t have to work as hard. If the ligament cannot do it’s job, it will cause tension in the longissimus muscle as it is called to do the job of the ligament. The supraspinous ligament is what allows the horse to be round over it’s topline. It is important that the saddle tree bridges over the ligament and rests on top of the longissimus and latissimus muscles over top the rib heads.
The longissimus muscle is the big long muscle that connects the neck to the sacrum. The purpose of the longissimus muscle is movement not to carry weight. Keeping the longissimus muscle relaxed should be the goal of every rider since tight back muscles will result in physical damage not to mention spooking and numerous other behavior and training issues.
The back of the saddle support area is at the 18th vertebrae, the last one connected to the ribs. The strength of the horse’s back allowing it to carry weight comes from all the muscles and ligaments intertwined in the ribs.
After the last rib is the lumbar vertebrae. The lumbar vertebrae have long delicate horizontal transverse processes. (shown in green above) Since they cannot support any weight, the muscles tighten to protect them resulting in back pain and need for chiropractic and massage therapy. Hock and stifle lameness can also be a symptom of sore back muscles resulting in arthritis and injections.
The latissimus muscle goes from the left front to the right rear. (shown in pink above) The latissimus muscle pulls the front leg back. Behind the saddle on top of the rump is the gluteus muscle. The function of the gluteus is to extend the hip joint. The gluteus muscle comes forward and ends in the lumbar area. (shown above with a yellow arrow behind the rider’s seat) Triggering the reflex of the gluteus with a saddle that is too long can cause an involuntary response also know as bucking or cold backed.
How sad it is for me to think of the horses that have been disciplined for an involuntary reflex reaction to a saddle because we didn’t know any better. Please help me to spread the word about saddle fit and how it affects our horse’s behavior, performance and ultimately the health of horse and rider. Share this information with your horse friends.
To prevent needless suffering and damage to our horses, the following guidelines are recommended.
- Shoulder Angle-Tree angle must match the angle of the scapula
- Tree Width-Tree should be wide enough to allow the saddle to sit level and the shoulder to pass through
- Wither Clearance-Adequate clearance on top and both sides of withers, usually 3-4 fingers
- Billet Alignment-Billets should hang perpendicular in the girth area 4 fingers behind the elbow
- Saddle Length-Weight bearing surface cannot go past last rib. Lumbar area should not carry any weight.
- Gullet Width-Wide enough not to interfere with vertebral spinal processes and spinal ligaments usually 4 fingers wide sometimes 3 or 5, never 2.
- Panel Contact-Panels should contact the longissimus straight and even from front to back
Terry Peiper, CSE
Saddlefit 4 Life Certified Saddle Ergonomist
Before moving to TN in 2017, Terry Peiper has been "Helping Horses With Their People" in MD and PA for over 35 years by training horses and riders. In addition to being an accredited Richard Shrake Resistance Free ® Trainer/Instructor, she is certified by the American Riding Instructors Association (ARIA) and the International Society of Rider Biomechanics. She has more than 45 years horse showing experience in several different disciplines, as well as several years of fox hunting and open show judging experience. You could say she has been there and done that.
Studying saddle ergonomics started out as just another way for Terry to help her students however, it quickly took over her life when she discovered that her own horse, Easy had a condition called kissing spine which was likely caused by many years of riding in poor fitting saddles. “I can’t go back and undo what I have done but I can spread the word about proper saddle fit to prevent other horses from needless suffering” says Terry.
Recognizing the huge need for proper saddle fit, Terry joined the Saddlefit 4 Life professionals and started the FIT RIGHT SADDLE SOLUTIONS. She passionately pursues her mission to educate as many riders as possible of the importance of proper saddle fit, how it affects the horse’s performance, behavior and ultimately the health of horse and rider.
Saddle fit evaluations/consultations, classes and Specialized/TW Saddles sales and service are available at 470 Copperhead Lane, Crossville TN (located on Rt. 127, 7 miles north of Interstate 40) or at other locations within 100 miles.