The effect of the PostureJac on deep cervical flexor endurance: implications in the management of cervicogenic headache and mechanical neck pain.

The convergence of cervical and trigeminal afferents on second-order neurons in the trigeminocervical nucleus may refer pain from the upper cervical spine into the head and face. Furthermore, "bi-directional interactions" between trigeminal and upper cervical afferents may also explain neck symptoms of trigeminal origin (e.g.