Your horse’s ribs are intimately involved in breathing, bend, swing, rotation and lift. Your horse’s ribs need to be able to move.
Your horse has 18 pairs of ribs (probably; some have 17, some 19). 8 ribs connect directly to the sternum and 10 ribs connect through fibrous tissue to the costal cartilage of rib 8 and end freely in the musculature. The ribs form a cage to protect the lungs and heart. In young horses, the ribs are quite soft. As your horse gets older they calcify and harden.
Each pair of ribs articulates with a vertebra.
Between the curved ribs lie the intercostal muscles.
Your horse’s ribs move in and out with each breath. Their ribs move closer together and farther apart for each stride or jump they take. The ribs move when your horse bends, lifts the back, reaches under, stretches, swing through the back and rotates through the barrel.
Tight or sore intercostals can cause your horse to hold its breath, to brace it’s barrel against movement or to habitually hold their rib’s to one side, interfering with their ability to bend evenly both ways or even canter on both leads. Tight ribs can also cause your horse to tip you to one side, compounding the problem.
If the ribs are tight, sore and restricted it they will interfere everything from your horse’s breathing to how your horse moves, through their own body and across the ground.
The intercostal muscles are quite a common place to be tight. They can be strained by a sudden movement, overuse, an unevenly weighted rider, an imbalanced saddle or lack of sufficient conditioning.
Slowly softening, relaxing and releasing the intercostal muscles and the fascia surrounding the ribs can help the horse regain motion and use of their ribs so they can move, and breathe, more freely, evenly and efficiently.