A very interesting study was completed comparing the effectiveness of suboccipital stretching versus direct stretching techniques in changing the range of motion of the hips. The suboccipitals are four muscles (rectus capitis posterior major and minor, obliquus capitis superior and inferior) they are located directly below the occiput or base of skull in the back of the upper neck and have a high density of proprioceptors. For this reason the neck is regarded as an important proprioceptive organ for postural processes. It has been shown by stretching this muscular group you can actually change the flexibility of the hamstrings.
Stretching the muscles in the back of the head and subsequently increasing the range of motion of the hamstrings is counterintuitive yet occurs. Researchers took this counterintuitve process of range of motion one step furthur, they examined what would happen to the hip flexors when stretching the same sub-occipital muscles that lengthened the hamstrings.
Using a reliable hand-held dynamometer to determine the end point of range of motions of joints, they divided subjects into three groups: cervical stretch, hip stretch and sham/placebo. In the sham/placebo group the researcher did movements that it was full well known elicited no results, the subjects were unaware that nothing would occur. After careful statistical analysis only the suboccipital groups stretching procedure increased hip flexion range of motion significantly.
Based on studies it appears that stretching the back of the neck not only increases the range of motion in the hamstrings, but also increases the range of motion of the hips. Training the head neck and jaw elicits many surprising positve performance results as the athlete Gets Strong.