Anatomical observation of a craniomandibular muscle originating from the skull base: the sphenomandibularis.

This study describes a hitherto unreported, functionally distinct craniomandibular muscle as observed in 25 cadaveric specimens and MRI scans of clinical patients. The muscle was consistently observed as originating from the maxillary surface of the sphenoid bone and inserting on the temporal crest (internal oblique line) of the mandible. This anatomic observation should broaden our understanding of craniomandibular function and may have clinical implications regarding retro-orbital pain.

Anatomic relation between the rectus capitis posterior minor muscle and the dura mater.

STUDY DESIGN: Anatomic study of the suboccipital region, specifically the deep muscles of the suboccipital triangle, was performed in cadaveric specimens. OBJECTIVE: To observe and describe the relationship between the deep suboccipital musculature and the spinal dura. SUMMARY OF BACKGROUND DATA: A review of the literature revealed no reports describing a physical connection between suboccipital musculature and the spinal dura. METHODS: Dissections of the suboccipital region were performed in 10 embalmed and one fresh sagittally hemisected head and neck specimens. RESULTS: A connective tissue bridge between the rectus capitis posterior minor muscle and the dorsal spinal dura at the atlanto-occipital junction was observed in every specimen. The fibers of the connective tissue bridge were oriented primarily perpendicular to the dura. This arrangement of fibers appears to resist movement of the dura toward the spinal cord. CONCLUSIONS: Awareness of the physical relation between the rectus capitis posterior minor muscle and spinal dura via this connective tissue bridge should lessen the potential risk of dural damage during surgery. This connective tissue bridge may help resist dural infolding during head and neck extension.

Accessory medial pterygoid muscle.

A previously undescribed accessory medial pterygoid muscle occurred uniformly in the dissection room population studied. The origin extends from the superior margin of the pterygoid plate and skirts medially of foramen spinosum and ovale, finally terminating on the carotid canal rim. The flat triangular muscle descends to insert its apex into the medial surface of the medial pterygoid muscle about 1 cm below its exit from the pterygoid fossae. Histologic examination confirmed striated muscle. Independent innervation arises from the medial surface of the mandibular nerve trunk just below the foramen ovale and enters the accessory medial pterygoid lateral surface at about the upper third, centrally. Muscle function is suggested as a discriminating action, rein-like in nature, probably corresponding to Bennett movement. Variation in size of this muscle may also explain the range observed for Bennett movement. The dental occlusal action field is suggested to be the buccal aspect of the last molar tooth.

Extensive caries in early man circa 110,000 years before present.

The example of Rhodesian man, who was approximately 35 years at time of death, had severe caries but physiologically adaptive attrition and periodontal status. Hypoplasia was not evident. Extensive caries seems to have occurred in the absence of modern bacterial strains and refined carbohydrates. It is suggested that the dentition was highly susceptible to caries because of a deficiency in elemental composition. Of the teeth examined, only the central incisors were free of caries and apparently resistant to disease. It is postulated that, as dental disease progressed, the Rhodesian man's diet changed and his techniques and abilities in processing food developed.

Ecology of dental disease.

Trace elements in the dental enamel of 43 prehistoric Indians from Illinois, Maryland and Virginia show concentration differences by age, sex and geographical locality. Sample areas on an incisor or first molar were blocked off with paraffin, washed twice with distilled water and etched 7 times with 6N HCl. An optical emission spectrophotometer was used to analyze the 9 samples, representing surface contamination and sequential enamel layers. Al, B, Ba, Cu, Fe, K, Mg, Mn, Na, Si, Sr, and Ti were present in most samples in micro or trace quantities; other elements were detected with less regularity. Comparisons of the 2 water washes with the 3 superficial, 4 deep and 7 total acid etches, suggest that during burial the residual inorganic portion of the enamel exchanged little or nothing with the soil. Enamel from archeological teeth may therefore be utilized in host factor studies in dental paleopathology. The Jy 50 Illinois Indians differ from the Potomac Creek, Virginia, Indians both in quantities of elements present and in internal sample variability. In each group, the sexes differ in 4 or more elements, both as to content and variability. Similarly, the older half of each sample differs from the younger. Patterns of sex and age difference are irregular, suggesting cultural differences, rather than physiological, in utilizing the environment during enamel-forming years. Enamel composition, as affected by differential environment utilization, may partially explain sex, age and geographical differences in dental pathology rates.

Enamel silicon and fluoride relationships demonstrating a surface silicon effect that facilitates fluoride uptake.

This study indicated that a clear relationship exists between silicon and fluoride. We have also demonstrated a probable surface enamel silicon effect that increases fluoride uptake. The complex set of relationships described in the surface chemistry of calcium, tin, and zirconium with fluoride, hydroxide, phosphate, and other surface-occurring ions need not be considered to confuse the specific silicon-fluoride relationship presented here because in this computation we are relating the changes in the silicon and fluoride ion values only. We have, however, considered the thermodynamics of such reactions and intend to elaborate on it in a later publication. We are aware of the small depth of fluoride penetration into enamel after topical treatment Health Foundation, Research Unit at the National Bureau of Standards, Washington, DC 20034, USA.