Is the lateral angle of the internal acoustic canal sexually dimorphic in non-adults? An investigation by routine cranial magnetic resonance imaging

The lateral angle of the internal acoustic canal is one of the measurements of petrous bone that has been previously studied for sex estimation, mostly in adults. We aimed at evaluating the effects of age, side, and sex on the lateral angle of the internal acoustic canal in pediatric patients.Pediatric routine cranial MRI studies were retrospectively investigated for this study. The lateral angle was measured on T2-weighted axial images when the anterior and posterior lips of the meatus and the cochlea were clearly visible on the same image. The data were evaluated for age, side and sex-related changes. Although 552 temporal bones from 273 patients were inspected, due to exclusion criteria lateral angle could be satisfactorily measured only in 101 temporal bones from 58 patients. The measurements did not differ significantly between sexes. An age-related, statistically significant decrease was observed for the entire pediatric sample studied, as well as for the males, but not for females. The measurements did not differ from side to side.The significant age-related decrease in lateral angle in male pediatric patients that was not detected in female counterparts may be the reflection of a sex-related difference in temporal bone development during childhood. Routine cranial MRI data may help investigators study age and sex-related changes in lateral angle in children.     

Computerized x-ray tomography of fossil hominid skulls

The newest generation of Computerized Tomography (CT) scanning appears to provide x-ray pictures of the internal structures of a rather heavily mineralized Homo erectus skull, i.e., Pithecanthropus IV, notably of its temporal bones, that reveal more details than traditional x-ray procedures. An analysis of the right temporal bone shows that it is extremely pneumatized, that the oval shape of the external meatus does not result from fractures as previously suggested, and that the middle ear and the internal auditory meatus have probably been damaged during restoration. Labyrinthine structures can be seen, and the facial nerve canal appears to be of a relative small size.     

Lateral angle: a method for sexing using the petrous bone

We report on the results of applying the so-called lateral angle method for sex determination on skeletal remains. The lateral angle denotes the angle of the internal auditory canal in relation to the medial surface of the petrous part of the temporal bone. The method involves making a small cast of the proximal part of the internal acoustic canal and determining the angle at which the canal opens up to the surface of the petrous bone. The method has the great advantage of utilizing one of the sturdiest bone elements of the human skeleton, and may thus be especially suited for analyses of very fragmented skeletal remains or cremated bones, where the petrous bone may still be readily recognizable. The method was tested using a forensic sample of 113 petrous bones with known sex. Intra- and interobserver testing was also performed. We found a statistically significant difference in angle size between males and females (mean angle size of males, 39.3 degrees ; mean angle size of females, 48.2 degrees ; P < 0.001). There was no bilateral difference in angle size. In blind trials, 83.2% of petrous bones were assigned to the correct sex. We also tested the lateral angle method against an archaeological skeletal sample. True sex was not known for this sample; instead, sexing had been carried out by assessing pelvic and cranial morphology in independent trials. We found a higher concordance between the lateral angle and "pelvic" sex than for lateral angle and "cranial" sex. Finally, we note that subadult sexing may also be possible with this method.     

The bony labyrinth of Neanderthals

This paper presents a comprehensive comparative analysis of the Neanderthal bony labyrinth, a structure located inside the petrous temporal bone. Fifteen Neanderthal specimens are compared with a Holocene human sample, as well as with a small number of European Middle Pleistocene hominins, and early anatomically modern and European Upper Palaeolithic humans. Compared with Holocene humans the bony labyrinth of Neanderthals can be characterized by an anterior semicircular canal arc which is smaller in absolute and relative size, is relatively narrow, and shows more torsion. The posterior semicircular canal arc is smaller in absolute and relative size as well, it is more circular in shape, and is positioned more inferiorly relative to the lateral canal plane. The lateral semicircular canal arc is absolutely and relatively larger. Finally, the Neanderthal ampullar line is more vertically inclined relative to the planar orientation of the lateral canal. The European Upper Palaeolithic and early modern humans are most similar, although not fully identical to Holocene humans in labyrinthine morphology. The European Middle Pleistocene hominins show the typical semicircular canal morphology of Neanderthals, with the exception of the arc shape and inferiorly position of the posterior canal and the strongly inclined ampullar line. The marked difference between the labyrinths of Neanderthals and modern humans can be used to assess the phylogenetic affinities of fragmentary temporal bone fossils. However, this application is limited by a degree of overlap between the morphologies. The typical shape of the Neanderthal labyrinth appears to mirror aspects of the surrounding petrous pyramid, and both may follow from the phylogenetic impact of Neanderthal brain morphology moulding the shape of the posterior cranial fossa. The functionally important arc sizes of the Neanderthal semicircular canals may reflect a pattern of head movements different from that of modern humans, possibly related to aspects of locomotor behaviour and the kinematic properties of their head and neck.     

Atresia of the external acoustic meatus in prehistoric populations

A case of atresia of the external acoustic meatus is presented from a prehistoric Late Woodland site in Iowa. The affected individual was a female aged 30 to 40 years. The left temporal bone displayed a thin bony plate occluding the external acoustic canal. No evidence of middle ear or inner ear malformation was observed on the axial tomographs, although the external canal was shortened. The individual is diagnosed as having a mild case of congenital atresia. The report extends the geographical and temporal distributions of this archaeologically rare condition.     

X-linked progressive mixed deafness: a new microdeletion that involves a more proximal region in Xq21.

We report a large two-generation pedigree with seven affected males segregating for an X-linked mixed conductive sensorineural deafness. The patients present with atypical Mondini-like dysplasia, dilated petrous facial canal, dilatation of the internal auditory meatus fully connected with enlarged cochlear canals, and, in one patient, a wide bulbous posterior labyrinth. Obligatory carrier females are mildly affected. Molecular characterization of this family revealed a deletion of locus DXS169, in Xq21.1. Loci DXS72 and DXS26, which, respectively, flank DXS169 proximally and distally, were intact. Since a gene responsible for X-linked progressive mixed deafness with perilymphatic gusher (DFN3) has previously been assigned by deletion mapping to a slightly more distal interval between DXS26 and DXS121, this study indicates either two different deafness genes or the involvement of a very large region in Xq21.     

Optimal Ancient DNA Yields from the Inner Ear Part of the Human Petrous Bone

The invention and development of next or second generation sequencing methods has resulted in a dramatic transformation of ancient DNA research and allowed shotgun sequencing of entire genomes from fossil specimens. However, although there are exceptions, most fossil specimens contain only low (~ 1% or less) percentages of endogenous DNA. The only skeletal element for which a systematically higher endogenous DNA content compared to other skeletal elements has been shown is the petrous part of the temporal bone. In this study we investigate whether (a) different parts of the petrous bone of archaeological human specimens give different percentages of endogenous DNA yields, (b) there are significant differences in average DNA read lengths, damage patterns and total DNA concentration, and (c) it is possible to obtain endogenous ancient DNA from petrous bones from hot environments. We carried out intra-petrous comparisons for ten petrous bones from specimens from Holocene archaeological contexts across Eurasia dated between 10,000-1,800 calibrated years before present (cal. BP). We obtained shotgun DNA sequences from three distinct areas within the petrous: a spongy part of trabecular bone (part A), the dense part of cortical bone encircling the osseous inner ear, or otic capsule (part B), and the dense part within the otic capsule (part C). Our results confirm that dense bone parts of the petrous bone can provide high endogenous aDNA yields and indicate that endogenous DNA fractions for part C can exceed those obtained for part B by up to 65-fold and those from part A by up to 177-fold, while total endogenous DNA concentrations are up to 126-fold and 109-fold higher for these comparisons. Our results also show that while endogenous yields from part C were lower than 1% for samples from hot (both arid and humid) parts, the DNA damage patterns indicate that at least some of the reads originate from ancient DNA molecules, potentially enabling ancient DNA analyses of samples from hot regions that are otherwise not amenable to ancient DNA analyses.     

Measurements of the tympanic cavity

The angle between the annulus fibrocartilaginous and the superior crest of the petrous bone was measured with 14 (10 to 19) degrees. The height of the annulus was in our material 10.04 mm, the width 9.45 mm. Measured were also the length of the plicae malleares and the height of the recessus membrane tympani anterior, posterior et superior with (2.5, 3.0 and 1.5 mm). In about 74%, the chorda tympani was imbedded in different zones of the plicae malleares. Its entrance and exit areas, the length of its intratympanal course and its width were measured. Included are also values of the ligaments of the otic ossicles, measurements of the ostium tympanicum tubae auditivae, of the epitympanic recess, the aditus ad antrum, and the antrum mastoideum. The eminentia pyramidalis, the sinus posterior and the sinus tympani, ponticuli and subicula, the fossula fenestrae cochleae and the fenestra cochleae, the fenestra vestibuli and prominences of the facial canal in the lateral semicircular canal have been researched and measured. Also the tympanic nerve and its course on the promontorium have been estimated.     

Insights into the mechanism of vascular endothelial cells on bone biology

In the skeletal system, blood vessels not only function as a conduit system for transporting gases, nutrients, metabolic waste, or cells but also provide multifunctional signal molecules regulating bone development, regeneration, and remodeling. Endothelial cells (ECs) in bone tissues, unlike in other organ tissues, are in direct contact with the pericytes of blood vessels, resulting in a closer connection with peripheral connective tissues. Close-contact ECs contribute to osteogenesis and osteoclastogenesis by secreting various cytokines in the paracrine or juxtacrine pathways. An increasing number of studies have revealed that extracellular vesicles (EVs) derived from ECs can directly regulate maturation process of osteoblasts and osteoclasts. The different pathways focus on targets at different distances, forming the basis of the intimate spatial and temporal link between bone tissue and blood vessels. Here, we provide a systematic review to elaborate on the function of ECs in bone biology and its underlying mechanisms based on three aspects: paracrine, EVs, and juxtacrine. This review proposes the possibility of a therapeutic strategy targeting blood vessels, as an adjuvant treatment for bone disorders.     

Canal systems in the temporal bone and their right-left differences

The first part of the facial canal is the pars labyrinthica. Its means lateral length is in our material 2.63 mm on the right and 3.03 mm on the left side. The mean width of the pore on the fundus area was 1.3 mm on the right side and 1.07 mm on the left. The geniculate fossa had a mean length of 2.54 mm on the right and of 3.14 mm on the left side. The widths of different areas of the pars labyrinthica and fossa geniculata were also measured. The angle between the first and second parts of the Fallopian canal was estimated with different methods. The mean width of the tympanic part of the facial canal was found to be 1.79 mm on the right side and 1.67 mm on the left, the mean width of the mastoideal part was 1.8 mm on the right side and 1.7 mm on the left. Distances of the mastoideal part of the Fallopian canal to mastoideal cells, ear drum, sigmoid sinus and external surface of the temporal bone were also measured. Measurements of the sigmoid sinus, the bulb of internal jugular vein and the cavum musculi stapedii are included, too. The ranges found in our material are also given.     

Distribution of structural and trace elements in human temporal bone

This study was undertaken to evaluate a systematic analysis of mineral and trace elements of individual functionally determined parts of adult temporal bone. Marked differences were observed in basic structural elements (Ca, P, Mg, and Zn) among different bone regions. The more so, molar Ca/P ratio was significantly different in various regions, being highest in the hammer and vestibular regions. Taxonomic analysis revealed specific differences in the mineral ratio between the two petrous bone regions believed to develop from various embryonal bases. According to results, the observed differences in mineral trace element composition of particular regions of human temporal bone might be explained by their developmental specificities and functional adaptation.     

Potentialities of temporal bone computed tomography in the study of the facial nerve and in the diagnosis of peripheral pareses of thr 7th pair of cranial nerves

Computed tomography (CT) was used to examine 200 patients (400 temporal bones) aged 3 to 74 years who had no signs of facial nerve lesion and 28 patients who had clinical manifestations of peripheral paresis of the facial nerve of varying genesis. Multipositional CT of the temporal bone is the most informative mode of visualization of the fallopian canal which is embodied on tomographic scans in 100% of cases irrespective of the age of a patient. CT data indicate that the formation of the facial nerve canal brings to completion by the age of 6 years. The following causes of n. facialis paresis were identified: facial neuroma; sarcoma of the temporal bone sarcoma; dehiscence of the canal wall in otitis media acuta; destruction of the tympanic wall of the canal in otitis nedia chronica, fractures of the temporal bone, anomalies of the fallopian canal in temporal bone malformations; stenosis of the canal in fibrous dysplasia. The detected alterations of the n. facialis canal permits further policy of management of a patient to be defined.     

The petrous bone--a new sampling site for identifying early dietary patterns in stable isotopic studies

Intraskeletal variation in the composition of carbon (delta(13)C) and nitrogen (delta(15)N) stable isotopes measured in collagen is tested from various human bones and dentine. Samples were taken from the femur, rib, and petrous part of the temporal bone from well-preserved skeletons of both adults (n = 34) and subadults (n = 24). Additional samples of dentine from the root of 1st molars were taken from 16 individuals. The skeletal material is from a medieval cemetery (AD 1200-1573) in Holbaek, Denmark. Our results indicate that the petrous bone has an isotopic signal that differs significantly from that of femur and rib within the single skeleton (P < 0.001 and P < 0.001, respectively), with only minor variation seen between femur and rib. On the other hand, there was no significant difference between the petrous bone and the 1st molar. The intraskeletal variation may reflect differences in turnover rate among skeletal elements. The inner periosteal layer of the petrous bone is formed in uterus and does not undergo any further remodelling after the age of 2 years, whereas the rib and femur have a continuous turnover rate of approximately 5 and 10-20 years, respectively. From the results of this study it is believed the petrous bone may be a new useful bone element and a supplement or a proxy for teeth in the analysis of early dietary patterns as it may reflect diet in fetal stages and early years of life.     

A comparative study of the temporal bone in three populations of man

A comparative study was made to determine race and sex differences in the temporal bone, to investigate growth relationships, and to establish a basis for phylogenetic studies of the temporal bone and the temporal lobe of the brain. Data on Eskimo, Indian, and white crania were collected from radiographs and directly from the skulls. Of the 25 variables studied, only the minimum diameter of porus failed to demonstrate some difference among the races. Variation between sexes was found for all measurements except the cranial base angle (of deflection) and three angles related to the petrous pyramids. Correlation coefficients indicated that none of the angles are related in any consistent manner to the other variables studied. This is interpreted as further evidence of cranial base stability. The Indians have the lowest, longest squamae, differing most from the whites. The position of squama is more anterior in the Eskimos. Females of each race possess more anteriorly positioned squamae than males. When the squama is more anteriorly located, the porus is in a more posterior position within the squama itself. Strong race variation exists in the shape of porus. In order to establish a basis for phylogenetic studies of the temporal lobe of the brain better reference points for reflecting its size and shape must be found.     

Computed tomography of the temporal bones in children with developmental anomalies of the external and middle ear]

Computed polypositional high-resolution tomography (CT) was provided to 45 children with dysplasia of the external acoustic meatus (EAM). The computed tomograms were analyzed in accordance with the scheme which included the evaluation of the following structures: atresia or stenosis area, pneumatized mastoid process, tympanic cavity, ant rum, osteal opening of the Eustachian tube, chain of auditory ossicles, windows of the labyrinth, internal ear, facial nerve canal, and large vessels. Preoperative CT of the temporal bones allows for the evaluation of the above-listed structures, which is of paramount importance for the planning of the patient management policy. Also, CT enables the assessment of the risk of surgical intervention associated with a potential injury to the facial nerve, large vessels, and temporomandibular articulation. CT is to be an indispensable diagnostic modality for examination of children presenting with EAM dysplasia.     

Evaluation of craniometric methods for determination of vertical dimension of occlusion

In clinical practice, fully precise method for exact determination of vertical relation of occlusion still does not exist. This study examines the relationship between different craniofacial distances and the distance subnasale-gnathion (Sn-Gn), which represents the lower third of the face in vertical relation determination. The highest coefficient of correlation was (r = 0.8678, p < 0.05) between the distance eye-ear (E-E = lateral border of the ocular orbit-medial opening of the meatus of the external auditory canal) and Sn-Gn. The prediction of the distance Sn-Gn could be determined through the formula: Sn-Gn = E-E/1.08 or through the regression analysis: Sn-Gn = 1.9197 + 0.6449 x E-E. None of the calculated coefficients of correlation was 1, but was < 1, so that the prediction of the distance Sn-Gn by craniometric distances is not absolutely reliable, although it is considerably helpful. Our results point at the variations of craniofacial distances in the Croatian population. Yet, craniometry could still be recommended in everyday clinical practice for prediction of vertical relation of occlusion, as it is a simple, economic and non-invasive method, however in combination with some other methods, which have proved to be helpful.     

Preoperative computed tomography of temporal bones and its use in selecting patients with sensorineural deafness for cochlear implantation

Cochlear implantation (CI) involves the insertion of electrode systems in the inner ear in order to restore hearing in patients with sensorineural deafness. Positive CI results are closely related with careful selection of candidates. Preoperative computed tomography (CT) and its results are decisive in this selection. Temporal bone CT was made in 40 patients aged 1 to 57 years who had sensorineural deafness. The following changes were detected: malformations of the inner ear, the inner auditory canal, meningititis-induced cochlear obliteration, post-traumatic temporal bone changes, local auditory ossicle malformation, inflammatory middle ear changes, the high position of the jugular vein bulb, and its diverticula. Temporal bone CT plays an important role in selecting candidates for CI and circumvents potential difficulties and complications at CI.     

Temporal bone CT in the diagnosis of acquired diseases of the external auditory canal

CT was used to examine 50 patients (100 temporal bones) aged 10 days to 60 years who had no signs of lesion of the external auditory canal (EAC) and 23 patients (27 temporal bones) aged 13 to 65 years who had clinical manifestations of acquired stenosis or obturation of the EAC. Polypositional CT of the temporal bone is the most informative technique of visualization of the osseous part of the EAC, at the same time the anterior and posterior EAC walls were evaluated in the axial projection and the upper and lower EAC walls were assessed in the coronary projection. According to CT data, formation of the osseous part of the EAC occurs within the first 7 years of a child's life. In the presence of EAC changes, CT may assess their pattern (a soft tissue or osseous one), their magnitude and location along the walls of the canal, the tympanic membrane, and other structures of the temporal bone. CT reveals the causes of acquired EAC obturation, stenosis, and atresia: osteocartilaginous exostoses, osteomas, polyps of the EAC, tumors of the temporal bone, as well as obturative keratosis and posttraumatic stenosis of the EAC. The detected EAC changes determine further management policy in a patient.     

A new reconstruction of the Le Moustier 1 skull and investigation of internal structures using 3-D-μCT data

Using the non-destructive technique of 3-D micro computed tomography (3-D-μCT), we present a new, virtual reconstruction of the Le Moustier 1 Neandertal skull. This new reconstruction corrects defects found in earlier reconstruction attempts by repositioning misaligned cranial fragments, addressing the problem of asymmetry caused by pressure during the fossilization process, and placing the basioccipital in its proper anatomical position. Metric comparisons between Le Moustier 1 and juvenile and adult Neandertals demonstrate that facial height proceeded at a faster rate of growth than facial prognathism at the beginning of the adolescent period. They also confirm the anterior placement of the basioccipital. A compound painted to match the colour of the fossilized bone was used in previous reconstruction attempts and the aim of this analysis was to remove the false material to reveal to what extent the fossilized bone was preserved. The areas with the most artificial material and glue include the palate, areas around the mandibular teeth, the left frontal, and parts of the right parietal and temporal bones. The μCT data were also used to examine internal structures of the skull including the frontal sinus and the labyrinth of the inner ear. An investigation of the frontal sinus reveals morphology similar to that found in adult Neandertals, although the structure does not extend to mid-orbit. The dimension of the radius of curvature of the lateral semicircular canal falls within one standard deviation, and the anterior and posterior canals within two standard deviations, of the published Neandertal mean. As in other Neandertals, the posterior semicircular canal is in an inferior position relative to the plane of the lateral canal.