The neutral or ortho-static head position (with horizontal Frankfurter plane) will allow healthy TMJ, craniovertebral, cervico-thoracic functions, and a stable occlusion (‘bite’). Rocabado further defined normal cervical lordosis and normal craniovertebral relationships based on cephalometric measurements. A line that connects the posterior nasal spine to the basi-occiput is called the McGregor’s plane or line. The odontoid plane (OP) is a line that extends from apex to the anterior inferior angle of the odontoid process. A normal measurement of the posterior-inferior angle (craniovertebral angle -CV) at the intersection of McGregor’s plane and OP is 101 degrees +/- 5 degrees (96-106 degrees). A distance between the basi-occiput to the posterior arch of the atlas is 4-9 mm (less than 4 mm indicates cranio-vertebral compression). When we lose this normal CV angle and assume a forward head posture, we also lose our normal or healthy cervical curve or lordosis, which can potentially lead to premature cervical spine joint degeneration and of course pain.
With forward head posture we increase the distance from chin to sternum stretching the hyoid muscles, which in turn will have the tendency to pull mandible back and down. This may also lead to the development of a retro-inclined profile (the chin posteriorly set) and mandibular malformation, as the mandible is being held posteriorly during growth and development. This can also be the start of creating a disc displacement issue with the temporomandibular joint as well as general myofascial pain of the muscles of mastication and the cervical spine.
By causing posterior cranial rotation and stretching of the infrahyoid muscles, forward head posture has the effect of increasing the activity of the masticatory muscles and cranial extensors, which often results in overuse, strain and pain. In this environment, the muscles of mastication pull on the mandible try to maintain a mouth closed position, while the infrahyoid muscles try to bring the mandible down and back. The constant fight between muscles that perform depression and elevation of the mandible is referred to as parafunction. Tension in these muscle groups will be reduced and balanced with proper therapy including restoring normal alignment of the craniovertebral angle and cervical lordosis on a stable shoulder girdle. Hence, the importance of finding a qualified physical therapist with appropriate certifications in the management of temporomandibular disorders (TMD).
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This is good info and a lot of work..thanks
I have a c7 radiculopathy creating many sensory and motor issues in right shoulder (periscapular especially). I have a right shifted mandible with possibly less molar occlusion on the right, no tmj pain just occasional clicking in the right tmj. I know forward head posture is indicated in radiculopathies. In your experience with radiculopathy patients do you consider treating a tmj/occlusion dysfunction as a means to free up the cervical spine?
I have head forward and recently my lower jaw has moved forward to where I cannot properly close my teeth together or really chew anything. My front teeth top and bottom now hit right on top of each other and are the only teeth that can touch together. This reading material says the mandible typically moves down and back…but with me, it is down and forward. It is actually even semi-hard to touch my front teeth together. Please reply
Hello, thanks for your question, I sadly would need a lot more info, for example have you been wearing any particular type of oral appliance that has caused this change in your bite or occlusion? Are you having TM joint pain on both sides and as a result you might have TM joint inflammation and now your condyles on each side cannot seat properly and you are touching in the front and not in the back. You could also possibly have bilateral spasm of both Inferior Lateral Pterygoids, which will protrude the mandible forward, result in anterior teeth contact but not back molar. And finally would like to know why you have forward head posture? Is it due to poor habits? Is there something structural occurring in your spine causing you to adapt this posture, and of course that can potentially effect your bite or occlusion. Thanks for the questions, sadly need more info. Mike
So here as well, would need far more info or an overall assessment. As with any musculoskeletal problems there can be what we call a top down or a bottom up approach to help with multiple issues, In my humble opinion, I subscribe to the philosophy you need to normalize the cervical spine first, then see what happens with your occlusion or bite, etc. Obviously if you have a potential Disc Displacement with Reduction on the right TMJ based on your info above these issues may correlate or they may be separate. It is a challenge and an art to determine what are the primary drivers vs. Secondary drivers or problems that result from the primary driver. My issues or concerns with fixing occlusion first, especially if you should opt for say some type of Irreversible therapy like implants or occlusal adjustments, you risk fixating your cervical spine then in a particular position and as a result worsening or at best maintaining your current C7 issue vs. Resolving it. I would personally want to get my C7 and any motor and or sensory issues resolved first thru a full c spine eval, neurodynamic testing, etc then see where my occlusion is at. Thanks, Mike
Does that mean it should be reverserable if you make an active effort to fix your posture and strenghten weak and losen tight muscles? Afterall this should affect how gravity pulls on your face.