Role of Cranial bone

 The 'TEMPORAL BONE - Keystone of the Cranium
One of the key factors in temporomandibular joint dysfunction involves distortion of the temporal bone. In an over simplified description.

the temporal bone represents the door frame and the mandibular condyle acts as the movable door if any distortion occurs to the frame it is a reasonable ssumption to expect a dysfunction of the door The temporal bones consist of three main parts the internal petrous portion the external squama and mastoid sections

The squama gives off a zygomatic process which extends forward and articulates with the malar bone and acts as the shock absorber for the TM joint in the cranial scheme the temporal bone articulates with the occiput parietals sphenoid malar and mandibular condyles its primary motion derives from the occiput which gently moves the temporal bones into internal and external rotation during the respiratory phases of expiration and inspiration respectively Two of the primary muscles of mastication.

Temporalis and masseter muscles. have a direct influence on temporal bone movement,. The large, fan-shaped temporalis muscle has part of its origin on the temporal squama and inserts on the mandible at the coronoid process and its anterior border.  

Spasm of this muscle will provide a powerful down-ward and anterior force a powerful down-word and anterior force upon the squama when the posterior teeth occlude. This force will have the effect of causing an external rotation i.e. the superior border of squama will move anteriorly and laterally while the mastold tips move superiorly, posteriorly, and medially.  
The mandibular condyles compensate by moving posteriorly and medially within the glenoid fossa. Intermal rotation of the temporal follows a movement that is directly opposite to that of extermal rotation-the mastoid tips move inferiorly, anteriorly and laterally while the superior order of the squama moves posteriorly and medially.

The condyle compensates in an anterior and lateral position within the fossa. Spasm of the sternocleidomastoid, splenius capitis, longus capitis and digastric muscles will induce an intermal temporal rotation.  

Balancing the movements of the temporal bone if the function of the stylohyoid and styloglossus muscles. These muscle attachments have their origin on the styloid processes and during con-traction function to inhibit and balance temporal motion.   Of further interest is the fact that temporal bone rotation affects the ten-sion on the tentorium cerebelli.  

Spasms of the temporalis, masse-ter, sternocleidomastoid, spienius capitus, longus capitus, stylo-hyoid, and stylogiossus muscles all can effect a temporal bone distortion.  

Extensive dural membrane attachments to the temporal bone make it vulnerable to distortion from other areas of the dural tube.  The temporal bone has extensive sutural articulations with the occiput, parietal, and spnenoid bones it functions between the two main cranial bone movers-occiput sphenoid bones-and provides a portion of the cranial base.  

Proper dynamics of temporal bone equilibrium is essential to a well functioning TM joint and to the entire structural scheme. Noxious influences are constantly working to upset this delicate balance. Distortions of muscles, fasciae, dural membranes, sutures, cerebrospinal fluid dynamics, etc. are all potential disruptive factors.  
The maxillary bone is of particular importance to the dentist. Distortion of this bone can be the etiological factor in facial pain, neuralgia, sinusitis, rhinitis, and odontalgia in the absence of frank pathology. Basic neuroanatomy will reveal the second division of the trigeminal nerve (V-2) and its posterior, middle and anterior alveola branches, greater palatine, nasopalatine, pteryopalatine ganglion and infraorbital nerves are closely related to the maxillaty bone. Often facial distortions can be attributed to maxillary bone dysfunction Gross anatomy  exhibits attachments of the medial ptetygoid, buccinator, zygomaticus major, elevator labi superior. levator anguli oris, and obigularis oculi to the maxilla. Clinically, one often observes facial distortions and eye dys-functional movement as a result of maxillary distortions.  
In the cranial scheme (excluding the three ear ossicles) the maxilla directly articulates with 45% of the cranial bones.
Sutural attachments are shared with the malar, frontal, ethmoid, vomer lacrimal, inferior nasal concha, palatine, sphenoid, and the other half of the maxillary bone.  



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