✅The longissimus dorsi (LD) is the longest and largest epaxial muscle in the horse's back, extending from the sacrum and pelvis to the cervical vertebrae. ✅lt acts primarily as a powerful thoracolumbar extender, lateral flexor, and stabilizer of the spine. ✅The LD is essential for lateral bending and, crucially, dorsal extension (stiffening the back). It acts as a bridge, transferring power from the hindquarters ✅During the walk, the LD shows one peak of activity, while at the trot, it shows two