Blog

Posted 02/28/2012

Have you ever tried to close a door and find that the door wouldn’t close?  Why is it that we always slam the door hoping that doing so will solve the problem?  All of us have had a door that doesn’t shut right, where the door runs into the door frame.  Individually, a door and a doorframe can be proficiently put together but if they are not made to match each other in size, the two will never work together.  To understand how a door functions, it is important to know what pieces go into a typical door system and the role that each plays.
The door jambs are the vertical sections of the door frame, which acts as a support for the remainder of the frame, as well as the door itself.  Each door frame has two jambs used to mount the frame to the surrounding wall.  The hinge jamb is the side where the hinges are installed, and the strike jamb is the where the door latches into the strike plate.  Hinges are the metal plates mounted on the door frame that anchors the door to the frame and allows the door to open and close freely.  The strike plate is the metal plate installed in the door jamb that receives the latch or lock when door is closed.  The top horizontal member of the frame that connects the two vertical jambs is called the header. The lower horizontal member of the frame that supports the entire door system is called the sill.
The structures that make it possible to open and close a door are very similar to opening and closing one’s mouth.  Indeed there is a mechanical relationship between the upper and lower jaw bones, the teeth, and the temporomandibular joints.  To understand how a mouth opens, it is important to know the anatomy of the mouth and the role that each plays.
TMJ stands for “temporomandibular joint” otherwise known as the jaw joint.  The joint is formed by the temporal bone of the skull (temporo) with the lower jaw (mandible) hence temporomandibular.  There is one temporomandibular joint on each side of the skull located in front of each ear.  The upper and lower halves of this joint are separated by an articular disc.  The temporomandibular joint is the most unique joint in the human body as it is two joints in one.  It is unique in that one joint directly influences the function of the other joint.  The two joints function as one unit since they both move one single bone, the mandible.  Each side cannot operate independently as both joints are joined to the same bone.
Think of your jaw as a door that is on hinges.  If your door is crooked, it is going to add excessive stress to the hinges and it is not going to shut correctly.  If you modify the door to make it look less crooked it is still going to have stress on the door and possibly not shut all the way causing further wear and tear to the door itself.  On the contrary, if you have a door that is straight and a door frame that is bent you may still have a door that does not shut correctly.  The next few blogs will discuss the various relationships that may be encountered when attempting to open and close one’s mouth using the door analogy.

Leave a comment for Jason!  Or to send him an email.

Posted February 28, 2012 at 4:17pm by Jason Masek.
Tagged With: biomechanics, PRI Concepts, temporomandibular • 1 Comment