In this post, we will look at DU 16 (fengfu) and the myodural bridge.
Studies over the past 20 years have revealed that there are myofibrous connective tissues bridging the suboccipital muscles (primarily the oblique capitis superior, rectus capitis posterior major and minor) to the dura mater of the upper cervical region. (Humphreys 2003).
This myofibrous connection occurs primarily through the posterior atlanto-occipital junction and atlanto-axial junction and is called the myodural bridge (MDB). The atlanto-occipital junction is where DU 16 (fengfu) is located and the atlanto-axial junction is where DU 15 (yamen) is located (Fig. 1).
Researchers have postulated that the myodural bridge has important functions related to proprioception and the dynamic circulation of the cerebrospinal fluid (CSF). (Hack GD 1995).
An influence on proprioception is most likely due to the fact that the suboccipital muscles have the highest muscle spindle content, when compared with the rest of the other human muscles. (Kulkarni V. 2001) However, how does the myodural bridge affect the circulation of cerebrospinal fluid? The author could not find any research to support the exact mechanism of the myodural bridge to the circulation of CSF, but is postulating it could be due the close proximity between the location of the myodural bridge and the median aperture of Magendie.
François Magendie, a French physiologist (1783-1855), discovered the median aperture of the fourth ventricle (Fig. 2 and 4). This aperture is the largest of three openings of the fourth ventricle. It measures between 4-9.4 mm and is located inferior to the cerebellum in the midline of the brainstem and, thus, it forms the main path for the outflow of the cerebrospinal fluid from this ventricle. (Ciolkowski M. 2011).
Magendie states, “There exists a communication between the exterior of the brain and its internal cavities, and through this foramen is a true entrance into the cavities of the brain.” (Stahnisch, F. W. 2009). Because the myodural bridge connects to the dura mater in the upper cervical region, it is possible that the mechanical force generated by movements of the upper neck could cause the DU 16 (Fengfu) and the myodural bridge tissue to pull or influence the median aperture, which in turn could benefit the circulation of CSF.
Researchers have found that the pathological changes of the myodural bridge may be a contributing factor to cervicogenic or chronic tension-type headaches. (Zheng N 2018). As we know, postural disparities and muscle imbalances can contribute to these types of headaches and are successfully treated with acupuncture and postural exercises. However, there is research on patients suffering from these types of headaches who have an imbalance in CSF in the brain. (Langemark, M.1995), (Bach, F. W. 1992).
The acupuncture point DU 16 (fengfu) is translated as “wind mansion” and is commonly used to treat headaches, neck pain and diseases caused by wind. This point is located directly below the external occipital protuberance and above the C1 posterior tubercle. The internal pathway of the Du Mai is described to enter the brain at DU 16 (fengfu) and connect with DU 20 (Fig. 3). The myodural bridge located at DU 16 seems to be the physical pathway of the Du Mai, by which an acupuncture needle can affect the brain.
The needle angle and for this point is commonly stated as perpendicular to the skin to a depth of 0.5-0.8 cun. The author prefers a perpendicular (with a 10˚ superior-oblique) angle directed 1-1.25 inches in depth depending on the size of the patient. It is useful to have the patient slightly flex the neck to help open the space when needling this point. Caution is advised.
Could acupuncture treatment to DU 16 have an effect on the CSF that could help reduce chronic tension headaches? This would be an interesting study and could shed some light on the anatomy and traditional function of this acupuncture point.
The author could not find very many English-translated research studies on the efficacy of this acupuncture point. Although, in a study on rats, it was found that the combination of DU 16 and DU 26 with electro-acupuncture greatly promoted neuroprotection and dorsal neuron function recovery after acute spinal cord injury. These results were speculated to be from the antioxidation, anti-inflammation and anti apoptosis effects of acupuncture. (Jiang, S. H. 2014).
- Bach, F. W., Langemark, M., Secher, N. H., & Olesen, J. (1992). Plasma and cerebrospinal fluid β-endorphin in chronic tension-type headache. Pain, 51(2), 163-168.
- Ciołkowski, M., Sharifi, M., Tarka, S., & Ciszek, B. (2011). Median aperture of the fourth ventricle revisited. Folia morphologica, 70(2), 84-90.)
- Humphreys BK, Kenin S, Hubbard B, Cramer G. Investigation of connective tissue attachments to the cervical spinal dura mater. Clin Anat. 2003;16:484–493.
- Kulkarni V, Chandy M J, Babu K S. Quantitative study of muscle spindles in suboccipital muscles of human foetuses. Neurol India 2001.
- Langemark, M., Bach, F. W., Ekman, R., & Olesen, J. (1995). Increased cerebrospinal fluid Met-enkephalin immunoreactivity in patients with chronic tension-type headache. Pain, 63(1), 103-107.
- Stahnisch, F. W. (2009). François Magendie (1783–1855). Journal of Neurology, 256(11), 1950-1952.
- Zheng, N., Chi, Y. Y., Yang, X. H., Wang, N. X., Li, Y. L., Ge, Y. Y., … & Sui, H. J. (2018). Orientation and property of fibers of the myodural bridge in humans. The Spine Journal, 18(6), 1081-1087.