Carolyn Cohen is an equine bodyworker, biomechanics expert, and independent tack fitter who founded her company, CC fits, in 2018. Her Equestrian Masterclass, Equine Biomechanics and Bodywork 101, teaches you about analyzing your horse’s movement and patterns in order to help him feel and perform his best.

Horses are incredibly strong and capable animals and with that comes a whole system of muscles working together to make sure they can perform at their best ability.

But, exactly what muscles are responsible for each particular movement?

Horses muscles are split into two different categories: extensor muscles and flexor muscles. 

Extensor muscles are a muscle whose contraction extends or straightens a limb or other part of the body whereas flexor muscles are a muscle that serves to flex or bend a part of the body. The extensor muscles run along the whole topline all the way through the hamstring and are used for extending through the back and lifting the head. Flexor muscles are below the spine and are responsible for bridging the head down, spine up, and are used for collection. 

The muscles along the horse’s abdomen are equally as important to focus on as those along the horse’s topline. To gain a better understanding of exactly how extensor and flexor muscles work together to allow our horses to move accordingly, learning exactly which muscles are responsible for which particular movement is key. 

Extensor muscles

Beginning with the extensor muscles, first we have the splenius. The splenius is responsible for the flexion of the neck and can actually become overdeveloped quite easily due to improper training. 

Next, we have the latissimus dorsi, which is actually the longest muscle in the body. This muscle runs and intertwines throughout the entire body all the way to the pelvis while also attaching to each vertebrae in the horse’s back allowing it to flex and extend. 

The glute muscles, the largest muscle in the hind end, is responsible for the power and extension of the pelvis and hip. The hamstring consists of a ton of muscles that are responsible for bringing the hind limb backwards primarily with the stifle and the hock. 

Flexor muscles

Moving into the flexor muscles, the brachiocephalicus is the main muscle in the neck and is below the splenius. This muscle brings the head down and allows for the head to flex side to side. If this muscle becomes tight, it can dramatically inhibit the horse’s motion making it difficult to go about everyday tasks.

The sternocephalicus allows the horse to open and close his jaw and bring his head down. The bicep and pectoral muscles are responsible for moving the limb forward and back and the abdominal muscles allow the horse to contract and push the pelvis forward. 

Throughout the entire abdomen lives a whole system of muscles that are conditioned to strengthen and support the spine. Similarly, the muscles around the hip are responsible for bringing the hip forward, supporting the pelvis and the shifting of weight. Last, but not least, the quadriceps are responsible for moving the limb forward.

All the muscles in the horses body are intertwined in some way or another and often work together in pairs. Learning the different muscles in the horse’s body and understanding how they work together is the first step in learning how your horse needs to be supported in terms of maintenance and recovery in order to perform at their best ability. 

This is an excerpt from Carolyn’s Equestrian Masterclass, Equine Biomechanics and Bodywork 101. To access the course, as well as a full library of courses from the likes of Ian Millar, Anne Kursinski and more, go to