what does the splenius muscle do
The splenius muscle is a superficial (top layer) muscle found on each side of the neck. It attaches the cervical (neck) and thoracic (upper back) vertebrae to the skull (mastoid process of temporal bone).ctivities that cause splenius muscle pain and symptoms in the horse: 1  A rider who constantly pulls or balances on the reins (lesson horse, rental horse). 2  A horse whose discipline requires collection and flexion of the head/neck (dressage, race horses).