Cranial osteopathy, a forerunner of CST, was originated by osteopath William Sutherland (1873–1954) in 1898–1900. While looking at a disarticulated skull, Sutherland was struck by the idea that the cranial sutures of the temporal bones where they meet the parietal bones were "beveled, like the gills of a fish, indicating articular mobility for a respiratory mechanism."
John Upledger devised CST. Comparing it to cranial osteopathy he wrote: "Dr. Sutherland's discovery regarding the flexibility of skull sutures led to the early research behind CranioSacral Therapy – and both approaches affect the cranium, sacrum and coccyx – the similarities end there." However, modern day cranial osteopaths largely consider the two practices to be the same, but that cranial osteopathy has "been taught to non-osteopaths under the name CranialSacro therapy."
Practitioners of both cranial osteopathy and craniosacral therapy assert that there are small, rhythmic motions of the cranial bones attributed to cerebrospinal fluid pressure or arterial pressure. The premise of CST is that palpation of the cranium can be used to detect this rhythmic movement of the cranial bones and selective pressures may be used to manipulate the cranial bones to achieve a therapeutic result. However, the degree of mobility and compliance of the cranial bones is considered controversial and is a critically important concept in craniosacral therapy.
From 1975 to 1983, Upledger and neurophysiologist and histologist Ernest W. Retzlaff worked at Michigan State University as clinical researchers and professors. They assembled a research team to investigate the purported pulse and further study Sutherland's theory of cranial bone movement. Upledger and Retzlaff went on to publish their results, which they interpreted as support for both the concept of cranial bone movement, and the concept of a cranial rhythm. Later reviews of these studies have concluded that their research did not meet enduring standards to offer conclusive proof for the effectiveness of craniosacral therapy and the existence of cranial bone movement.