I stand corrected. The shoulder girdle is not part of the core as is asked in the question. Please allow me to clarify.
It does have an affect on core stability. We know that “hip and trunk muscle strength, abdominal muscle endurance, the ability to maintain a particular spinal or pelvic alignment and the absence of ligamentous laxity in the vertebral column have all been identified as core stability.” Scapular stability is involved in this.
The anatomy of the core as defined by NASM Essential of Fitness Training is “the lumbo-pelvic-hip complex and the thoracic and cervical spine, where the body’s center of gravity is located.
The shoulder girdle does act on the thoracic spine, hence my confusion.
It would be foolhardy however to train the “core” and not include scapular stability.
Thank you all the heads up! 8))