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The temporal bone: Trouble maker in the head Temporal bone HAROLD I. MAGOUN, SR., D.O., FAAO Belen, New Mexico function, produce tension in nerves or fascia, and generally upset homeostasis in this area. Physicians knowledgeable about osteopathic Likewise, many of the problems in the area of theory and procedures in the cranial field the eye, ear, nose, and throat have roots in have found it possible to relieve many structural abnormalities that affect the tem- conditions that result from abnormalities poral bone. Temporal bone syndromes, how- in the position and motion of temporal bones. ever, go far beyond these areas of practice. Structural deviations of these bones may be This may seem to be a questionable concept responsible for migraine headaches, vertigo, to physicians who were led to believe that the strabismus, and malocclusion of the teeth, skull is a solid ivory tower. This misconception as well as bruxism and nystagmus. has arisen because textbook writers started Correction of these deviations is not a with a false premise. Their descriptions were cure-all, but often long-standing conditions written from study of dry, defatted laboratory erroneously attributed to other causes may specimens, not of living, resilient bone. To be relieved by manipulative measures. It contemplate flexibility in a structure that does not require a great deal of training to through the ages has been considered im- perceive movement or to detect slight mobile calls for flexibility in the thinking distortions or lack of motion. process. Basic anatomy Before the position and/or motion of the tem- poral bone are considered in relation to the disorders possibly connected with abnormal- Pursuant to his observation that the spheno- ities thereof, it would be well to review the squamous suture is "beveled like the gills of a general anatomy and the physiologic move- fish and indicating articular mobility," Suther- ment involved. land delved into the intricacies of the anatomy Each temporal bone makes up the middle of and joint physiology of the temporal bone, one side and the base of the skull, filling in be- especially at the sutural bevel, as few others tween the sphenoid bone with its sphere of in- ever have done. His studies led him into a fluence anteriorly and the occiput and its therapeutic complex involving a field so vast sphere of influence posteriorly. The fact that that he was led to call the temporal bone "the the mandible articulates with the temporal trouble maker in the head." Trouble maker or bones tends to complicate these relations. victim of circumstances, this structure is in- Each temporal bone consists of three parts. volved in a wide range of pathologic condi- The scalelike squama carries the external tions. Consequently, a knowledge of its rela- ear and the zygomatic process. The breastlike tionships is of great importance to any mastoid process contains the mastoid cells and physician or dentist. the antrum, but the mastoid is not fully de- From the dental point of view, perversion of veloped until near the end of the first year of physiologic motion or traumatic fixations in- life. The petrous portion, named for its rock- evitably will disturb temporomandibular and like consistency, houses the important organs occlusal harmony, alter muscle position and of hearing and equilibrium, forms the medial Journal AOA/vol. 78, June 1974 825/89 Temporal bone wall of the middle ear cavity, and carries the It should be noted further that the pet- exit of the bony part of the eustachian tube. rosphenoid articulation also is cartilaginous Shaped like a pyramid, it contains many im- throughout life—a sign that it is designed for portant structures. Its posterior surface is motion—and that the petrous ridge, just back pierced by the opening of the internal acoustic of its anterior tip, is notched to allow for the meatus for the seventh and eighth cranial crossing of the root of the fifth cranial nerve. nerves, as well as the vestibular aqueduct for Also in this immediate area the forward the ductus endolymphaticus. The anterior sur- reaches of the tentorium cerebelli, known as face is hollowed at its mesial end to accommo- the petrosphenoid ligaments, insert into the date the trigeminal ganglion and contains also posterior clinoid processes of the sphenoid the hiatus fallopii of the greater superficial bone overlying the sixth cranial nerve on petrosal nerve. Inferiorly there are attach- either side. ments for muscles, the pharyngeal aponeuro- In order to understand the possible patho- sis, the opening of the carotid canal, the jugu- logic influences of the temporal bone, one must lar surface for articulation with the jugular visualize the basic anatomic relations just de- process of the occipital bone (cartilaginous scribed. To appreciate its physiologic motion, throughout life), and the styloid foramen for one must be familiar with the sutural bevels the seventh cranial nerve. All these are im- around its entire periphery (Fig. 1). An over- portant in one type of pathologic change or simplified description of these sutural con- another that is related to abnormal position formations might state that the upper half of or unphysiologic motion. the bone is beveled internally, at the expense Fig. 1. Interior view of the left temporal bone. 826/90 of the inner table of bone, where it articulates veloped abnormally can be most significant. A with the parietal and sphenoid bones. At the blow on the jaw is transmitted directly to the sphenosquamous and the condylosquamomast- skull by way of the temporomandibular artic- oid pivots, the bevel becomes external in its ulation. But the temporal bone suffers the lower half, at the expense of the outer table most. Trauma to the vault or base, to the fron- of bone. The structure might be compared tal bone or occiput, can hardly escape disturb- roughly to that of a casement window swing- ing the temporal bone because of the added ing externally above and internally below its complication of its position between the horizontal axis. spheres of influence of the sphenoid bone and Noting this conformation, Sutherland 2 the- occiput. It has to absorb or compensate for orized that a temporal bone could be disarticu- diverse influences from both ends. lated from an intact skull with the proper lev- The lifelong pattern of position of the tem- erages. The head of the anatomy department poral bone and consequently of the ear is de- of one of the osteopathic colleges insisted that termined perinatally. Without giving the mat- this was preposterous, that this could not be ter a thought one is inclined to overlook the done with a crowbar. In this he was correct, varying positions of the ears of ones daily but Sutherland succeeded in removing just the companions, whether they are close to the undamaged temporal bone with a penknife. head, divergent, or a combination of these. This spurred him to further study. His conclu- Indeed, anatomists who judge from dry, dead sions have been supported by continuing clini- laboratory material have concluded that the cal experience. idea of "bone rotation as a cause of protrusion The minute detail of normal physiologic of the ears is unsound and somewhat laugh- motion is best left for the classroom and per- able." Surely they would not use a dead fence sonal instruction. It can be found in the text- post as the criterion of the motion of a live book.1 Suffice it to say that in external rota- tree, swaying in the breeze with the sap still tion, minute though it be, the petrous ridge in it. How could the great variation in ear po- turns about an arbitrary axis running from sition be explained other than to say that the jugular surface to the petrous apex. This perinatal influences mold the infants cranium carries the superior border of the petrous por- and so alter the position of the temporal cart- tion anterolaterally toward the periphery. At ilages, which soon ossify? the same time the superior border of the Generally speaking, with brachycephalic squama moves anterolaterally, the tip of the heads the temporal bones are physiologically in zygomatic process moves inferiorly, but both external rotation so that the ears protrude the mastoid process and the mandibular fossa laterally (Fig. 2). This is not always true, move posteromedially. Internal rotation is in however. With dolichocephalic heads the tem- the opposite direction. Studies of cranial mo- poral bones usually are in internal rotation tion3 may be found in the literature. with the ears close to the head, but this also It must be emphasized that motion is mi- may vary. These characteristics can be seen nute, but it can be recognized readily by a easily. The more minute variations, usually physician trained in the concepts of osteo- with one ear rotated slightly internally and the pathic medicine in the cranial field. Pathologic other slightly externally, are common. They change occurs when the physiologic motion is may be obvious to the trained observer, or they disturbed, limited, or prevented completely. may be perceived only by astute palpation. This often occurs in the perinatal period. Ob- They are always meaningful, reflecting plagio- viously, with the rapid growth of preosseous cephaly resulting from trauma. A contributing elements, membrane and cartilage, during that factor is found in muscular insertion. The time, such disturbances can be of great sig- number of muscles inserted into the temporal nificance, with distortion or retardation of de- bone is smaller than that of muscles that at- velopment, limiting of function, etcetera. tach to the sphenoid bone, but there is a con- Later in life trauma to relatively normal siderably increased degree of tension on the structures and certainly to those that have de- temporal bone because of the lateral position Journal AOA/vol.

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