The aim of this study was to provide data on various dimensions of the normal cochlea using three-dimensional reconstruction based on high-resolution micro-CT images. The petrous parts of 39 temporal bones were scanned by micro-computed tomography (CT) with a slice thickness of 35 lm. The micro-CT images were used in reconstructing three-dimensional volumes of the bony labyrinth using computer software. The volumes were used to measure 12 dimensions of the cochlea, and statistical analysis was carried out. The dimensions of cochleae varied widely between different specimens. The mean height and length of the cochlea were 3.8 and 9.7 mm, respectively. The angle between the basal and middle turns was slightly larger in males than in females, while none of the other 11 dimensions differed significantly between males and females. The cochlear accessory canals were observed in about half of the cases (51.3%). Correlation analysis among measured items revealed positive correlations among several of the measured dimensions. The present study could investigate the detailed anatomy of the normal cochlea using high-resolution imaging technologies. The results of the present study could be helpful for the precise diagnosis of congenital cochlear malformations and for producing optimized cochlear implants.

To provide anatomical and morphological data regarding the coccyx using three-dimensional images, with a view to aiding the diagnosis of idiopathic coccydynia, one hundred and thirty-six normal adult pelvises were investigated. Three-dimensional models of the pelvis were reconstructed using software from computed tomography images of whole specimens. The following six coccyx parameters were measured: (1) width, (2) straight length, (3) thickness, (4) sacrococcygeal angle, (5) intercoccygeal angle, and (6) angle of lateral deviation of the coccyx. The presence of fusion between the sacral and coccygeal cornua, and between the sacrum and the transverse process of the coccyx was also investigated, and lateral deviations of the coccyx were classified and analyzed. Most of the measured coccyx parameters were larger in males than in females, with the exception of the sacrococcygeal and intercoccygeal angles. Unilateral or bilateral fusion of the sacral cornu and the coccygeal cornu was not a rare finding. With respect to the sacrum and the transverse process of coccyx, the separated type was more common than the fused type. The incidence and angle of lateral deviation of the coccyx varied widely between individuals. The present detailed description of the gross anatomy of the coccyx obtained using three-dimensional modeling will help toward understanding the mechanism underlying the development of idiopathic coccydynia. Fusion of the sacrum and coccyx or lateral deviation of the coccyx may cause coccydynia by compressing the coccygeal nerves. Anat Rec, 299:307-312, 2016. V C 2015 Wiley Periodicals, Inc.

It is generally accepted that the three semicircular canals are set at right angles to each other and the lateral semicircular canal is smaller than the anterior and posterior semicircular canals. Precise knowledge of the size and spatial relationships of the semicircular canals is vital, and so the 40 petrous parts of the temporal bones were scanned by micro-CT at a slice thickness of 35 mm. The micro-CT images were used in reconstructing three-dimensional models of the bony labyrinth using computer software. Various dimensions of the semicircular canals were measured using the software, and statistical analysis was performed. The anterior semicircular canal was slightly wider than the posterior semicircular canal, and their heights were similar. The radius of curvature of the lateral semicircular canal was 20% smaller than those of the anterior and posterior semicircular canals. The angles between the three canals were not exactly 90 degrees: they were 92.1, 84.4, and 86.2 degrees between the anterior and posterior, anterior and lateral, and posterior and lateral semicircular canals, respectively. We obtained high-resolution images of the semicircular canals using three-dimensional reconstruction software, and these were used to precisely measure the angles between the semicircular canals and the area of the distorted circle formed by each semicircular canal. Anat Rec,

Posterior projections of the ophthalmic division of the trigeminal nerve (the ophthalmic nerve) are distributed in the tentorium cerebelli as recurrent meningeal branches. We investigated the morphological tentorial distribution of the ophthalmic nerve. Fifty-two sides of the tentorium cerebelli and adjacent dura mater obtained from 29 human specimens were stained using Sihler's method to examine the nerve fibres in the dural sheets. The innervation patterns of the tentorium cerebelli were classified into the following four types according to their distributions: Type 1, where nerve fibres projected to both the straight and transverse sinuses; Type 2, where nerve fibres projected only to the transverse sinus and lateral convexity; Type 3, where nerve fibres projected medially only to the straight sinus and the posterior part of the falx cerebri; and Type 4, where the nerve fibres terminated within the tentorium cerebelli. Images of the tentorium cerebelli were superimposed to identify areas of dense innervation. The incidence rates of Types 1-4 were 71.2% (n = 37), 21.2% (n = 11), 3.8% (n = 2) and 3.8% (n = 2), respectively. More branches of nerve fibres traversed towards the transverse sinus posterolaterally than towards the straight sinus medially. The space between the anterior half of the straight sinus and the medial tentorial notch can be considered a safe surgical area where innervation is scarce. The posterior part of the falx cerebri was innervated by the ophthalmic nerve that traversed to the straight sinus. The parietal branches of the middle meningeal artery in the lateral convexity that were projected orthogonally by the ophthalmic nerve traversed the transverse sinus, implicating their vulnerability and possible sensitivity under physiological or neurosurgical conditions. This study has revealed the macroscopic tentorial innervation of the dura mater in humans, which could be useful information for both neurosurgeons and neurologists.

To investigate the topographical relationship between the frontal branch of the superficial temporal artery (FSTA) and the temporal branch of the facial nerve (TFN) with the aim of preventing nerve injury during FSTA biopsy. Fifty-seven hemifaces of 33 cadavers were dissected. Vertical lines drawn to the lateral orbital margin (LOM) and the superior root of the helix were used as the anterior and posterior reference positions, respectively. Horizontal lines drawn through the supraorbital margin and lateral canthus were used as the superior and inferior reference points, respectively. The depth and course relationships of the FSTA and TFN were examined. Midpoints between the FSTA and TFN are situated approximately 6.0 and 4.5 cm posterior to the lateral orbital margin at the levels of the lateral canthus and supraorbital margin, respectively. The TFN is generally situated 1-2 cm anteriorly and inferiorly to the FSTA in the temporal region. However, in two cases (3.6%), the TFN ran just underneath the FSTA with only a very small safe distance, making it highly vulnerable to iatrogenic injury. In conclusion, when performing an FSTA biopsy, the surgeon should not dissect below the superficial temporal fascia because there is an overlap between the course of the FSTA and the TFN in a minority of cases. Also, surgical incisions should be made outside the area delineated by an oblique line passing through the points 6.0 and 4.5 cm posterior to the lateral orbital margin at the levels of the lateral canthus and the supraorbital margin, respectively. Clin. Anat. 31:608-613, 2018. © 2017 Wiley Periodicals, Inc.