Mastoid Fossa Research Articles

Morphometric Study of Supra-meatal Triangle and Mastoid process in the Adult dry Skulls

Introduction: This study was done with an objective to do a craniometric study of supra meatal triangle and mastoid process to explore the variations as a determinant to sex. Methodology: A total of 47 skull bones formed our study sample which comprised of 31 males and 16 females Six landmarks were identifi ed on each side of the skulland measurements were taken using Digital Vernier caliper with precision of 0.01. Observations and Results: The area of supra-meatal triangle in male was 134.68± 21.69 mm3 on the right side and 134.17± 16.98 mm3 on the left side. In females the area of supra-meatal triangle was 114.82± 21.99 mm3 on right side and 122.46± 24.05 mm3 on the left side. In male skulls, the length, breadth and width of the mastoid process on the right side was 23.56 ± 2.88, 19.81 ± 2.49 and 11.46 ± 2.51 mm and the left side measurements were 23.33 ± 2.17, 18.93 ± 1.91 and 10.84 ± 2.39mm respectively. In females the length, breath and width of mastoid were 23.03 ± 2.94, 18.87 ± 2.42 and 10.03 ± 2.32 mm on right side and 22.06 ± 1.99, 17.85± 2.22 and 9.43 ± 1.89 mm in left side respectively. conclusion: In this present study the supra meatal triangle and all measurements of mastoid process were greater in males with the mastoid breadth and width showed statistically signifi cant values. The fi ndings can be applied to unknown skull samples or bone fragmentsand can provide insight to future studies of forensic anthropologists and ENT surgeons.

Morphological and clinical significance of the suprameatal region: a topographic study

The suprameatal approach, which does not require mastoidectomy, uses the method of tunneling over the facial nerve to enter the middle ear in cochlear implantation. Even if the SMA approach is also used to drain the mastoid antrum, the depth of the triangle and protrusion types may be important for surgical approaches in this region. This descriptive study was conducted with 58 dry skulls found in the laboratories of the University Faculty of Medicine. Important landmarks were used on the left and right sides of the skulls. All the distances were measured with a vernier caliper to the nearest millimeter. No statistical significance was found between the right and left sides (p>0.05). The border lengths of the suprameatal triangle were respectively 14.88±1.67 mm, 18.17±1.09 mm, 14.56±1.59 mm on the right and 15.34±1.65 mm, 19.01±0.56 mm, 15.89±0.52 mm on the left. Consequently, it was determined that the left side was wider than the right, and there was statistical significance between the sides. The mean ST area was found to be 112.7±16.90 mm2. The crest was observed mostly on the right side (n=30 (51.72%)), and the triangular suprameatal protrusion was observed mostly on the right side (n=10 (31.03%)). We think that knowing this area’s borders and morphological features well, nominated before the surgical procedure, will be a guide in preventing possible operative and postoperative complications.

Desmodilliscus braueri crania compared to Pachyuromys duprasi (Desmodilliscini, Gerbillinae, Rodentia)

Abstract Molecular phylogenies support the monophyly of Desmodilliscus braueri and Pachyuromys duprasi as a clade basally split from all other gerbillines. While this monophyly supports their placement in a single tribe (Desmodilliscini), no morphological synapomorphies exist among desmodilliscines. This study compares the scale-independent cranial shapes of these two species using geometric morphometrics to determine how they differ and/or converge. Tribal synapomorphies, should they exist, may appear as interspecifically invariable cranial regions. No such invariable cranial regions were detected. The two species significantly differed in cranial size and shape. A small part of shape variation was allometric, with a weak unique allometric effect. No sexual size nor shape dimorphism was found. The sister taxa greatly differed in almost all cranial features, with Pachyuromys (when compared to Desmodilliscus) having a larger-sized cranium, with a larger bulla and suprameatal triangle, a more posteriorly placed palatine foramina, and more anteriorly shifted (and reduced) rostral cranial structures, due to being crowded by the hypertrophied bulla. Cranial variation patterns are consistent with the literature. The extreme morphological divergence among these species is explained by the distant divergence time and ecological differences. Absence of cranial shape synapomorphies does not preclude synapomorphies in other craniodental morphological features (e.g., detailed morphology of the dentition and cranial foramina) or in other morphological structures, such as the postcranial skeleton.

Morphometric study of Macewan’s Triangle in Relation to Depth of the Sigmoid Sinus Plate

Background: The suprameatal triangle is used for approaching the tympanic cavity and also it is an importantlandmark for otologic surgeons during mastoidectomy.Aim: To determine the depth of sigmoid sinus plate over the Macewan’s triangle by morphometry of variousanatomical landmarks.Materials & Methods: The study was carried out in the Department of Anatomy, Penang InternationalDental College & VMKV Medical College, Salem on 30 dry human adult skulls. Five landmarks (D1,D2, D3, D4, D5 and D6) were taken on the left and right sides of the skulls and the imaginary lines wereconstructed and measured by Vernier caliper between the landmarks.Results: The measurement of D2 showed statistically significant differences. The correlations of D1, D3,D4, D5 and D6 on both sides do not show any significant differences. The linear correlation equations werederived using the measurements for predicting D6.Conclusion: The depth of sigmoid sinus plate (D6) can be assessed using D1, D2, D3, D4, D5 on lateralview of head & neck X-rays which can be used by Otologist during mastoidectomy to avoid severe bleedingcomplications from sigmois sinus.

Anatomical landmarks to locate the junction between transverse and sigmoid sinuses in translabyrinthine and retrosigmoid open surgical approaches

Introduction Hematoma due to dural-sinus damage is a known complication when introducing burr holes in open transcranial surgery. Our objective was to identify safe areas to avoid dural-sinus damage based on anatomical landmarks in translabyrinthine and retrosigmoid open surgical approaches where neuronavigation facilities are not available. Methods A descriptive anatomical study was conducted on adult skulls. Distances to transverse and sigmoid sinuses on either side were measured using fixed anatomical landmarks: asterion, inion, margins of suprameatal triangle and superior nuchal line. Measurements were standardized according to the cranial indices (cranial index=anteroposterior diameter/transverse diameter) of each skull. Results Thirty-two adult skulls (male:female=22:10) were studied. Mean cranial index, width of transverse and sigmoid sinuses were 0.785±0.045, 9.1±2.3mm and 9.7±1.2mm respectively. Mean vertical distances from asterion and inion to the transverse sinus were 1.1±3.4mm and 14.7±5.9mm respectively. Posterior border of the sigmoid sinus was located 14.7±5.9mm, and 59.9±7.4mm anterior to asterion and inion respectively. t-tests did not show significant differences of these distances on either sides (p>.05). Pearson's correlations were insignificant between the measurements and the cranial indices (p>.05). Measurements from the suprameatal triangle to the dural-sinuses had the minimum variance. In >95% of the times the sigmoid sinus was located ≤23 mm posterior and ≤7 mm superior to the suprameatal triangle. Discussion and conclusions Suprameatal triangle was a consistent surface landmark to locate dural-sinuses. Dural-sinus damage could be avoided in 95% of the times by placing burr hole at least 7mm superior and 23 mm posterior to the suprameatal triangle.

MASTOID PROCESS – A TOOL FOR SEX DETERMINATION, AN ANATOMICAL STUDY IN SOUTH INDIAN SKULLS

Objective: The aim of this study is to evaluate the use of mastoid process as a tool for sex determination in unidentified skeleton. Methods: Eighty (40 male and 40 female) complete undamaged skulls of known sex in book record were used for the study. Eight different measurements on the right mastoid of each skull were recorded. Measurements were made using vernier calipers (0.01mm). The values were subjected to univariate and multivariate analysis employing SPSS Windows 13.00 version program. Results : Statistics revealed high significance (p 0.000) in five measurements except Asterion porion, Posterior end of incisura mastoidea - depression of suprameatal triangle and Asterion-depression of suprameatal triangle. Direct method with all parameters gave discrimination accuracy of 82.5% and in step wise analysis an accuracy of 65.0%. Stepwise analysis selected Mastoidale Porion as the best discriminant. Conclusion : Reports on the use of mastoid process as a tool for sex estimation in unidentified human skeleton has been reported in different populations. The present study supports this finding among the South Indian population.

Using basic statistics on the individual patient's own numeric data

IntroductionThis theoretical report gives an example for how coefficient of variation (CV) and quartile analysis (QA) to assess outliers might be able to be used to analyze numeric data in practice for an individual patient. MethodsA patient was examined for 8 visits using infrared instrumentation for measurement of mastoid fossa temperature differential (MFTD) readings. The CV and QA were applied to the readings. The participant also completed the Short Form–12 health perception survey on each visit, and these findings were correlated with CV to determine if CV had outcomes support (clinical significance). ResultsAn outlier MFTD reading was observed on the eighth visit according to QA that coincided with the largest CV value for the MFTDs. Correlations between the Short Form–12 and CV were low to negligible, positive, and statistically nonsignificant. ConclusionThis case provides an example of how basic statistical analyses could possibly be applied to numerical data in chiropractic practice for an individual patient. This might add objectivity to analyzing an individual patient's data in practice, particularly if clinical significance of a clinical numerical finding is unknown.

Sex Estimation from the Mastoid Process Among North Indians*

Determination of sex from fragmentary crania is a critical problem in forensic anthropology. Osteometric analysis of mastoid can serve forensic anthropologists better in sex identification by virtue of the noticeable dimorphic characteristics. The present study aims to develop population-specific, sex-differentiating anthropometric standards for the mastoid process of North Indian skulls. Eight parameters of the mastoid region were measured on 138 adult crania (M/F 104:34, 22-65 years) and analyzed using SPSS 16.0. All parameters showed significant sexual dimorphism (p < 0.000). In stepwise analysis, asterion-mastoidale and mastoid breadth have provided an accuracy of 87%. Receiver operating characteristic curves were obtained for each variable to observe their overall performance in sex determination. Posterior end of incisura mastoidea-depression of suprameatal triangle was found to be the best variable with maximum area under curve and highest predictive accuracy (82.6%).

Morphological comparison of fourteen species of the genus Meriones Illiger, 1811 (Rodentia: Gerbillinae) from Asia and North Africa

Genus Meriones is the dominant member of gerbils in the Palaearctic region, particularly in aride region of Asia. This is also one of the most typical genus of subfamily Gerbillinae with about 17 morphospecies namely: M. persicus, M. hurrianae, M. zarudnyi M. vinogradovi, M. meridianus, M. libycus, M. crassus, M. tristrami, M. rex, M. tamariscinus, M. unguiculatus, M. shawi, M. grandis, M. sacramenti, M.dahli, M.chengi, M.arimalius . Of which first eight species have been recorded from the Iranian Plateau. There are minor differences between some species and hence, interspecific discrimination of specimens from each species is not always possible, even by polytechnic methods using different taxonomic characters such as tympanic bullae, suprameatal triangle and external characters on material from museums and dental characters on archeozoological materials. Here, 26 morphological characters of 384 museum specimens belonging to 14 morphospecies of Meriones from North Africa, Iran and Central Asia were studied. This study review, 14 species of Meriones and based on the results, it seems that M.libycus, M. crassus and M. meridianus are complex species and need taxonomic revision. The cladistics analysis shows that M. vinogradovi could be forming ancestral species of genus Meriones, and west of Caspian Sea could be the center of origin for Meriones. Due to the presence of convergence regarding adaptation of different species of Meriones to similar environment, subgeneric morphological characters may cause homoplasies and paraphyletic subgenera the analysis of morphological character states matrix, using Mix program of Phylip shows different four clades that did not conform to the nominative subgenera and unveil probable homoplasy.

Standard deviation analysis of the mastoid fossa temperature differential reading: a potential model for objective chiropractic assessment

Objective This study describes a model for statistically analyzing follow-up numeric-based chiropractic spinal assessments for an individual patient based on his or her own baseline. Methods Ten mastoid fossa temperature differential readings (MFTD) obtained from a chiropractic patient were used in the study. The first eight readings served as baseline and were compared to post-adjustment readings. Results One of the two post-adjustment MFTD readings fell outside two standard deviations of the baseline mean and therefore theoretically represents improvement according to pattern analysis theory. Conclusion This study showed how standard deviation analysis may be used to identify future outliers for an individual patient based on his or her own baseline data.

Micro–computed tomographic scanning of the ear region of Cainotherium: character analysis and implications

ABSTRACT Most recent phylogenetic analyses place the Cainotheriidae within the Tylopoda, but doubts about this placement within Tylopoda have been persistent. The Cainotheriidae are well known from numerous specimens and their cranial anatomy is well documented from complete, partial and disarticulated cranial material. However, high-resolution computed tomographic (CT) scans can still provide additional data to resolve problems in the interpretation of the auditory region, and allow comparison with other tylopod and ruminant taxa. Cainotheriids share several features with various groups within the Tylopoda, including an enlarged mastoid fossa, an inflated auditory bulla filled with cancellous bone, the presence of a sinus venosus temporalis, and what has been interpreted as a large flange of the periotic enclosing the petrobasilar canal. The reconstruction of the petrobasilar canal has been difficult to interpret, as the published figures are unclear. A micro-CT scan of Cainotherium (YPM 25037) shows the morphology is more complex. The periotic shows a smaller flange that does not enclose the petrobasilar canal. The skull base shows different arrangement of bones from other artiodactyls, presumably as a result of the enlargement of the auditory bulla, which has also affected the course of the petrobasilar canal. The otic region of Cainotherium shows no resemblances to ruminants, and features of this region are consistent with the Cainotheriidae being either a sister taxon to Tylopoda + Ruminantia, or with inclusion in a tylopod grouping.

Elliptic Fourier analysis on the tympanic bullae in three Meriones species (Rodentia, Mammalia): its application in biosystematics

Abstract. The size and shape of the auditory bullae are investigated across three species of Meriones, in order to determine the biosystematic value of bulla characteristics in species recognition. This study is based on outline (geometric morphometric) with elliptical Fourier and eigenshape analysis of tympanic bullae in: (a) the suprameatal triangle, (b) the mastoid, (c) the auditory meatus, and (d) the ventral view of bullae. The results show that characters of the auditory meatus separate these three species from each other. The shape of different parts of the bullae within each species is also shown to vary such as in two populations of M. persicus. The shape of organs is important in the interaction between the organism and its environment. Tympanic bullae variation is similar in the Geno population of M. persicus (Geno is located in south of Iran), and in M. libycus which lives in similar climates. The results of this analysis of tympanic bullae differ from the characters described by CORBET (1978).

Intraexaminer and interexaminer reliability of mastoid fossa readings using a temporal artery thermometer

Objective The temperature of the mastoid fossa region has been measured by chiropractors since the 1950s using various instruments. The reliability of the procedure is largely unknown for the various instruments used for this purpose. This study assessed the reliability of a thermal instrument designed to measure forehead temperature while having an alternate landmark as the mastoid fossa. Methods: Thirty students were recruited to participate. Three blinded examiners twice scanned each student with the temporal artery thermometer. Intraexaminer and interexaminer reliability was assessed using the intraclass correlation coefficient. Differential margins of error were also calculated. Results Intraexaminer reliability was acceptable in 6 of 6 assessments, whereas interexaminer reliability was acceptable in 3 of 4 assessments. The maximum mean differential margin of error was 0.54 for intraexaminer reliability and 0.46 for interexaminer reliability. Discussion Combining the mean maximum differential margin of error for intraexaminer (0.54°) and interexaminer (0.46°) and then averaging these 2 ([0.54 + 0.46] / 2) results in a maximum mean differential margin of error of 0.50°. Conclusion In this study, intraexaminer reliability ranged from fair to strong. For these examiners, fossa differentials of 0.5 can be considered within the margin of error.

Cochlear implantation in the cochlea with an anteriorly-located sigmoid sinus

The standard surgical technique for cochlear implantation consists of mastoidectomy, posterior tympanotomy and cochleostomy (facial recess approach). We performed cochlear implantation in a patient with an anteriorly-located sigmoid sinus, which made posterior tympanotomy impossible. Since the short process of the incus was partly defective in this case, the electrodes of the cochlear implant (Nucleus 24) were introduced through the space from the epitympanum to mesotympanum after opening the epitympanum from the area superior to Macewen's triangle. The cochleostomy was performed by a transmeatal approach. All 22 electrodes and 10 dummies were inserted into the cochlea without any resistance.

Informative Value of Temperatures in Different Areas of the Human Body for Correcting Body Thermal Imbalance during Extravehicular Activities

Identification of noninvasive and informative sites on the body reflecting the development of body thermal imbalance during extravehicular activities (EVAs) is highly important for enhancing astronaut safety. Temperature changes were evaluated on several areas of the head (the mastoid fossa (Tmf), the forehead (Tfo), and the cheek (Tch)) and on the fingers (Tfing). Subjects were dressed in a multicompartment liquid cooling/warming garment. Studies I and II consisted of different combinations of hood versus garment cooling or warming imposed across stages; studies III and IV involved sagittally divided cooling or warming regimes with the hood worn (study III) or with the head uncovered (study IV). In studies I and II, Tmf significantly (P < 0.05) differed between stages 2, when the head was cooled and the rest of the body heated, and 3, when the head was heated and the rest of the body cooled. The Tmf changes were consistent with the thermal conditions imposed on the head but not reflective of the developing body heat deficit. In study III, the Tmf at stages 2 and 3 on the right or the left followed the thermal conditions on the ipsilateral side of the body (P < 0.01). In study IV, Tfing showed no significant differences across stages. In studies I–IV, Tfing showed consistent changes across stages (P < 0.05), reflecting the developing body heat deficit. In all studies, there were no significant differences in rectal temperature (Tre) across stages. Tmf and temperatures at other head skin sites did not respond in accordance with the actual intensity of a heat or cold flux from the garment and were not reflective of the overall development of body thermal imbalance. Tfing was a more adequate indicator of initial thermal destabilization and provided information that would be useful for monitoring the thermal balance and comfort during EVAs.

Balanced auricular reconstruction in dystopic microtia with the presence of the external auditory canal.

This article presents a new repositioning method in dystopic microtia (low-set microtia, anteriorly tilted microtia, or both) with the presence of the external auditory canal. In the case of low-set malformations, the dystopic auricular canal complex was freed from adjacent bony structure, shifted upward, and anchored to the thick periosteum of the suprameatal triangle or the adjacent superior portion of the temporal bone with nonabsorbable sutures. When the auricular vestige was large and dystopia was severe, the complex was shifted with attachment of the temporoparietal fascia on its cranial part. Meanwhile, when the auricular vestige was small and dystopia was mild, the complex was shifted without attachment of the temporoparietal fascia. Then, the ear framework fabricated with autogenous costal cartilage was positioned and wrapped with the temporoparietal fascial flap. In the case of anteriorly tilted malformations, the dystopic complex was freed, shifted posteriorly, and anchored to the periosteum of the suprameatal triangle. Preauricular dead space, resulting from shifting the complex, was obliterated with pieces of costal cartilage. Simultaneously, the ear framework was placed and wrapped with the temporoparietal fascial flap. No skin necrosis of the shifted complexes occurred in any of the cases. In one case, the facial nerve was transected during dissection and reanastomosed. Upward repositioning distances in low-set microtias were between 1 and 3.5 cm. Posteriorly repositioning distances in anteriorly tilted microtias were 2 and 3 cm. Thirteen patients with low-set malformations, two patients with anteriorly tilted malformations, and three patients with low-set and anteriorly tilted malformations underwent reconstructive operations. The new repositioning method is relatively simple, safe, and effective.

The cranium of Bunomeryx (Artiodactyla: Homacodontidae) from the Upper Eocene Uinta deposits of Utah and its implications for tylopod systematics

ABSTRACT Observations of four crania of the homacodont artiodactyl Bunomeryx suggest that this taxon has strong affinities with the Tylopoda. In particular, Bunomeryx possesses a deep mastoid fossa on the endocranial surface of the petrosal, a feature which is confined, within the living artiodactyls, to the Camelidae. Mastoid fossae are also found in members of the Cainotheriidae, Anoplotheridae and Xiphodontidae (collectively Anoplotheroidea), suggesting that the presence of a mastoid fossa may be a feature linking Bunomeryx to more derived artiodactyl taxa in the late Eocene of North America and Europe. Expansion of the ventral margin of the petrosal and its contribution to the roof of the petrobasilar canal, together with a reduction in the size of the internal auditory meatus, are characters which may unite a broader grouping of camelids, anoplotheroids, oreodonts and bunomerycids. While not providing any additional evidence for the ongoing debate on the ruminant affinities of the protoceratids, the information obtained from Bunomeryx may strengthen the case for a monophyletic clade including the taxa listed above, but excluding protoceratids.

Various types of suprameatal spines and depressions in the human temporal bone.

Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep.

Diagnostic Characters and Distribution of Meriones Illiger, 1811 Species (Mammalia: Rodentia) in Turkey

In this study, specimens of Meriones collected from various areas of Turkey were evaluated based on morphological and biometrical characters. It was determined that four species; Meriones tristrami, Meriones vinogradovi, Meriones meridianus and Meriones crassus exist in Turkey. External characters such as the terminal tuft on tail, the colour of ventral hairs, the soles of hind foot and the length of tail, and cranial characters such as the structure of suprameatal triangle, the connection of anterior rim of auditory meatus to squomosal and the projection of mastoid portion of tympanic bullae from supraoccipitals were determined to be useful in distinguishing species of Meriones. The range of M. tristrami in steppes and plains below altitude of 1200 m in Anatolia, M. vinogradovi in vicinity of Kars and Iğdır province, M. meridianus at sandy belts in the north of Ağrı mountain and M. crassus in Southeastern Anatolia were determined.

The Postnatal Growth of the Temporal Bone and its Implications for Cochlear Implantation in Children

The postnatal growth of the human temporal bone was examined by direct anatomical measurements on 60 cadaver specimens of all ages. The bones were dissected as one would perform cochlear implant surgery using a posterior tympanotomy approach. Nineteen anatomical/surgical landmarks with implications for cochlear implant surgery were identified on each bone and the distance between these points measured. The temporal bone was found to be a complex structure, phylogenetically, anatomically and functionally consisting of four different parts with independent postnatal development. The inner and middle ears were adult size at birth. The external auditory canal and most parts of the temporal bone were subject to significant lateral growth. The size of the pneumatised mastoid increased in all directions. In the facial recess, however, no postnatal growth was observed. Between birth and adulthood an average of 12 mm (SD 5 mm) of growth was seen directly between the sino-dural angle and the round window, the landmarks approximating the implantation site for the receiver-stimulator and the electrode entry point into the inner ear. However, if an electrode leadwire is fixed at a cortical fixation site such as the posterosuperior point of Macewen's triangle, the leadwire would be subject to approximately 20 mm of growth. These results indicate that a paediatric cochlear implant design incorporating an expandable leadwire to accommodate this growth should allow up to 25 mm of leadwire lengthening. The fossa incudis showed no growth relative to the round window and was found to be a convenient fixation site for the electrode array close to the cochlea. From an anatomical and surgical point of view, cochlear implantation in very young children is feasible, provided the electrode array is secured and the design accommodates for controlled leadwire lengthening.