Clinical assessment of the deep cervical flexor muscles: the craniocervical flexion test
The craniocervical flexion test is a clinical test of the anatomical action of the deep cervical flexor muscles, the longus capitis, and colli. It has evolved over 15 years as both a clinical and research tool and was devised in response to research indicating the importance of the deep cervical flexors in support of the cervical lordosis and motion segments and clinical observations of their impairment with neck pain.
The craniocervical flexion test could be described as a test of neuromotor control. The features assessed are the activation and isometric endurance of the deep cervical flexors as well as their interaction with the superficial cervical flexors during the performance of five progressive stages of increasing craniocervical flexion range of motion. It is a low-load test performed in the supine position with the patient guided to each stage by feedback from a pressure sensor placed behind the neck. While the test in the clinical setting provides only an indirect measure of performance, the construct validity of the craniocervical flexion test has been verified in a laboratory setting by direct measurement of deep and superficial flexor muscle activity.
Research has established that patients with neck pain disorders, compared to controls, have an altered neuromotor control strategy during craniocervical flexion characterized by reduced activity in the deep cervical flexors and increased activity in the superficial flexors usually accompanied by altered movement strategies. Furthermore, they display reduced isometric endurance of the deep cervical flexor muscles. The muscle impairment identified with the craniocervical flexion test appears to be generic to neck pain disorders of various etiologies. These observations prompted the use of the craniocervical flexion action for retraining the deep cervical flexor muscles within a motor relearning program for neck pain patients, which has shown positive therapeutic benefits when tested in clinical trials.