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PURPOSE: The precise location of the endolymphatic sac (ES) may be difficult during surgical approaches. This morphometric study aimed to determine the exact location of ES in adult human cadavers for the management of pathologies such as Meniere's disease. METHODS: Twenty temporal bones of 10 adult cadavers (mean age: 70 ± 13.40 years, range: 45-92 years; sex: 4 males and 6 females) fixed with 10% formalin were bilaterally dissected to obtain numeric data about the location of ES. RESULTS: Distances of ES to the posterior semicircular canal (PSC), Donaldson line (DL), sigmoid sinus (SS) and sinodural angle (SA) were found as 2.76 ± 1.18 (0.96-5.58) mm, 1.74 ± 1.13 (0.58-5.07) mm, 2.30 ± 1.09 (0.54-4.91) mm and 16.04 ± 3.15 (9.82-22.18) mm, respectively. In addition, the angle between the tangents passing through the cortical bone (CB) and SS was determined as 35.37°±11.32° (21.30°-60.58°). No statistical difference was found between right-left or male-female measurements (p > 0.05). CONCLUSION: DL, SS, and PSC are essential anatomical landmarks for determining the location of ES. The spatial location of SS, including its depth to the cortical bone and the distance to anteriorly located anatomical structures of the mastoid cavity consisting of the facial nerve and PSC, is believed to be underlined for ES surgery. Our data may be used as a database to further define the relationship between ES and adjacent anatomical structures (SS, PSC, etc.) during the application of surgical approaches.

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BACKGROUND AND PURPOSE: The nasal base muscles are of great functional importance in health and disease. Particularly, the one lacking terminological consensus, but often termed as myrtiformis muscle, which has been mostly omitted by anatomists may have significance for rhinoplasty. The purpose of the current study was to re-examine the anatomical features of myrtiformis muscle. MATERIALS AND METHODS: Conducted on 40 sides of 20 formalin-fixed amputated heads, we followed a dissection routine to fully expose the origin and insertion sites of the nasal base muscles. We measured the respective morphometric via digital caliper. RESULTS: Based on the number of bellies and their muscular attachment sites, we described an anatomical classification that consists of three different types of MM which had a single and broad origin. We classified the double-bellied muscle as Type 1 occurred in 10% (4/40), whereas the single-bellied ones as Types 2 and 3, occurred in 80% (32/40) and 10% (4/40), respectively. Measured distance between the medial margin of myrtiformis muscle origin and midline passing through the anterior nasal spine did not differ between any statistical comparisons (P > 0.05). CONCLUSION: We revisited the muscle which was at some occasions termed as myrtiformis muscle, depressor septi nasi or depressor alae nasi muscles. Considering that there are differential forms of the muscle with the same muscular origin but bearing single or double bellies and/or different insertion sites, our classification may overcome possible terminological confusion by ensuring single muscle term with easily distinguishable morphological types. We invite anatomists to enlarge the data set and comment on our classification, and surgeons to conduct prospective examinations to add deeper insight regarding the functional importance of anatomical classifications by correlating pre vs post-operative functional differences.

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This study aimed to determine the precise localization and course of parotid duct based on morphometric data obtained by measurements regarding several superficial landmarks and lines. Totally, 46 parotid ducts of 24 formalin-fixed adult amputated heads (12 female and 12 male) aged between 45 and 92 years, present in the collection of Anatomy Department, School of Medicine, Mersin University, were evaluated. First, three reference lines were defined: L1: between intertragic notch and labial commissure, L2: between intertragic notch and nasal wing, and L3: between intertragic notch and lateral palpebral commissure. The location of the parotid duct with respect to these lines were recorded. In all sides, parotid duct was detected in the middle 1/3 of L1. In 71.7% of all hemifaces, the parotid duct was making an upward curve around L1. Its proximal end exiting from the anterior border of the parotid gland was 12.34 ± 28.83 mm below the proximal 1/3 point of L1. Then, it was crossing L1 at a point with a mean distance of 53.90 ± 9.69 mm from the labial commissure where it is almost at L1 midpoint. Its distal end was located 9.61 ± 2.88 mm above the distal 1/3 point of L1. In 21.7% of all hemifaces, PD was observed totally above L1, while the shortest distances of its proximal and distal ends to L1 were 4.35 ± 2.45 mm and 13.17 ± 4.52 mm, respectively. In 6.5% of all hemifaces, its proximal end was located just on L1, coursing upwards and terminating 11.76 ± 2.53 mm above L1.

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BACKGROUND: We sought to describe the innervation patterns of the foot lumbrical muscles and their morphological properties in human fetuses and to define the communicating branches between the medial (MPN) and lateral (LPN) plantar nerves, which play a part in the innervation of those muscles. METHODS: Thirty formalin-fixed fetuses (13 male and 17 female) with a mean ± SD gestational age of 25.5 ± 3.8 weeks (range, 18-36 weeks) from the inventory of the Mersin University Faculty of Medicine Anatomy Department were bilaterally dissected. Innervation patterns of the lumbrical muscles and the communicating branches between the MPN and the LPN were detected and photographed. RESULTS: No variations were seen in lumbrical muscle numbers. In the 60 feet, the first lumbrical muscle started directly from the flexor digitorum longus tendon in 48 and from the flexor hallucis longus slips in addition to the flexor digitorum longus tendon in 12. Fifty-five feet had the classic innervation pattern of the lumbrical muscles, and five had variations. No communicating branches were seen in 48 feet, whereas 12 had connections. CONCLUSIONS: This study classified innervation patterns of the foot lumbrical muscles and defined two new innervation types. During surgeries on the foot and ankle in neonatal and early childhood terms, awareness of the communicating branches between the MPN and the LPN and innervation of the intrinsic muscles of the foot, such as the lumbrical muscles, might aid in preventing possible complications.

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OBJECTIVES: Skull base is an important and a challenging area for surgeons. Success in skull base surgery depends on various factors such as pre-operative evaluation, appropriate surgical technique, anesthesia duration, intraoperative neuromonitorization and wound care. MATERIALS AND METHODS: This study was performed in the Anatomy dissection laboratory of M.U. Medical Faculty (Ethical committee approval number 2010-103). Twelve fetuses between 17-33 gestational weeks fixed with formaldehyde were enrolled to the study. RESULTS: This study was planned to investigate the cross sectional areas of the sigmoid sinus in three levels to compare the right-left sides and the probable relationship among the levels in fetuses to further delineate the developmental factors on jugular foramen asymmetry. The cross-sectional measurements of sigmoid sinus lumen were done on 3 levels which are described as A1 level; sinodural angle, A2 level; the midpoint between the sinodural angle and endocranial orifice and A3 level as the entrance (endo-cranial orifice) of the jugular foramen. There is a strong positive correlation between left (L) A1 and L A2 and also the same for L A1 and right (R) A2. These strong and positive correlations are all valid between L A2-L A3, L A2-R A2, L A2-R A3, L A3-R A3, R A1-R A2. CONCLUSION: Multicenter studies would be beneficial to investigate the topic with greater number of fetuses also on the different regions for genetic differences.

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PURPOSE: The aim of present study was to reveal slip transfers related to flexor hallucis longus (FHL) and flexor digitorum longus (FDL) by dissection and to investigate detailed structure of chiasma plantare composed of FHL-FDL tendons and quadratus plantae (QP), with precise composition of the long flexor tendons of lesser toes by histological sections in human fetuses. METHOD: Slip transfers related to FHL and FDL tendons were identified and the related morphometric measurements were taken with dissection in 28 formalin-fixed fetuses (25-40 weeks). Composition and restoration of chiasma plantare and long flexor tendons of lesser toes were traced histological by analyzing movements of the tissues on the sequential coronal sections in five fetuses in the third trimester. The numbers of layers constituting chiasma plantare and the muscles that formed layers were specified. Each of two to five flexor tendons arising from the chiasma plantare was analyzed regarding its formation and contribution of FHL slip. RESULTS: Slip transfers were found as FHL slip in 86% and cross-connections in 14%. The ratios of the slip width to that of FHL and FDL tendons were found higher than in adult literature. Variance in the involvement of slip to FDL and QP, formation and layering of chiasma plantare and formation of long flexor tendons from chiasma plantare were revealed and great similarities were found with data from dissection of adult in literature. CONCLUSION: Slip transfers between FHL and FDL tendons, and layering properties of chiasma plantare were largely finalized during intrauterine period, while structural changes in slip seem to continue in the later stages of life, possibly by the effects of growth and usage of the extremity. In addition to individual variations, investigating the contribution of FHL slip, FDL and QP to long flexor tendons by different methods in literature is also suggested to be responsible for some diversities of our histological study.

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OBJECTIVES: The main aim of the study was to examine the development and course of the facial nerve within fetal temporal bones from an anatomical and neuro-otological perspective. METHODS: The study was conducted on 32 temporal bones from obtained fetuses (7 females, 9 male), on a mean gestational age of 26.75 ±â€¯4.36 (range, 20-34) weeks from the collection of the Anatomy Department of Medicine Faculty. All the measurements were collected with a digital image analysis software. RESULTS: Neither male/female nor right/left significant differences were observed in relation with the algebraic data of the segment lengths and angles of the facial nerve (p > 0.05). Linear functions for meatal, labyrinthine, tympanic, and mastoid segment lengths of the facial nerve were calculated as: y = -1.206 + 0.200 × Age (weeks), y = -1.868 + 0.153 × Age (weeks), y = -2.327 + 0.325 × Age (weeks), and y = -1.507 + 0.246 × Age (weeks), respectively. In addition, linear functions for first and second genu angles were calculated as: y = 105.475-0.117 × Age (weeks) and y = 140.446-0.042 × Age (weeks), respectively. CONCLUSION: The regression equations and the scatter plot with increment curve, representing the growth dynamics of the facial nerve can be used for estimating its lengths and for understanding its development. The data suggest that there is a dramatic change transition from fetal life to the gathered data of adulthood in the length of meatal and mastoid segments as well as in the second genu angle; in addition, there is a partial change in the length of labyrinthine and tympanic segments as well as in the first genu angle.

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BACKGROUND: We sought to show the biomechanical and morphometric properties of flexor hallucis longus (FHL) and flexor digitorum longus (FDL) tendon grafts harvested by specific surgical approaches and to assess the contribution of FHL slips to the long flexor tendons of the toes. METHODS: Thirteen fresh-frozen amputated feet (average age, 79 years) were dissected. The connections between the FHL and FDL tendons and the contribution of FHL slips to the long flexor tendons were classified. The biomechanical properties of the tendons and slips were measured using a tensile device. RESULTS: The connections between the FHL and FDL tendons were reviewed in two groups. Group 1 had FHL slips (11 cases) and group 2 had cross-slips (two cases). The FHL slips joined the second and third toe long flexor tendon structures. Tendon length decreased significantly from the second to the fifth toe (P < .001). Apart from the second toe tendon being thicker than that of the fourth toe (P = .02) and Young's modulus being relatively smaller in the third versus the fourth toe tendon (P = .01), biomechanical and morphometric properties of second to fourth tendons were similar. Mechanical properties of those tendons were significantly different from fifth toe tendons and FHL slips. Morphometric and biomechanical properties of FHL slips were similar to those of the fifth toe tendon. CONCLUSIONS: Herein, FHL slips were shown to have biomechanical properties that might contribute to flexor functions of the toes. During the harvesting of tendon grafts from the FHL by minimally invasive incision techniques from the distal plane of the master knot of Henry, cutting slips between FHL and FDL tendons could be considered a cause of postoperative function loss in toes.

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PURPOSE: The main objective of the study was to examine the use of teres major (TM) as a flap in the pediatric surgeries from an anatomical perspective by: (1) revealing the growth dynamics of the developing TM; (2) assessing the possible interconnecting structures between TM and latissimus dorsi (LD); (3) exposing the innervation patterns of TM in human fetuses. METHODS: Study was conducted on 50 fetuses (26 females and 24 males), on a mean gestational age of 22.86 ± 3.21 (range 18-30) weeks. All the measurements were collected with a digital caliper and a digital image analysis software. Additionally, structural relations between TM and LD were examined in detail and further classified. RESULTS: No significant difference of side and sex was detected on TM measurements (p > 0.05). Linear functions for the surface area, width, length of the superior and inferior margins of TM were detected as follows: y = - 257.142 + 18.334 × age (weeks), y = - 5.497 + 0.545 × age (weeks), y = - 1.621 + 1.068 × age (weeks), and y = - 2.147 + 1.284 × age (weeks), respectively. As classified in five types, a number of 33 muscular or tendinous connections between TM and LD were detected. Musculo-tendinous slips from TM to triceps brachii (TB) were evident in four sides. Innervation of TM was observed to be providing by the lower subscapular nerve in all the cases. CONCLUSION: First, linear functions, representing the developing fetal morphometry obtained by our study can be adapted for estimating the morphometric of this muscle in early childhood. Besides, acknowledging the diverse appointments of TM with the surrounding muscles such as LD and TB may facilitate the prevention of neurovascular structures and the application of surgical procedures during tendon transfers. In brief, our findings are highly potent to bring the attention of pediatric surgeons.

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This study is intended to obtain the algebraic growth dynamics of the gracilis in fetuses and determine the variations of neurovascular pedicle(s) of the gracilis, to aid infant surgeries. Forty fetuses (19 males and 21 females) were included in the study. Gestational mean age of the fetuses was 22.40 ±â€Š2.67 (range, 18-28) weeks. Numerical values were obtained using a digital caliper and a digital image analysis software. Linear functions for the surface area, width, anterior, and posterior margin lengths of the gracilis were calculated, respectively, as: y = -289.307 + 20.501 × age (weeks), y = -7.113 + 0.622 × age (weeks), y = -24.421 + 3.434 × age (weeks), and y = -24.397 + 3.314 × age (weeks). In addition, length and width of the gracilis tendon were calculated as y = -6.676 + 0.934 × age (weeks) and y = -0.732 + 0.074 × age (weeks), respectively. Parameters of the gracilis had no statistically significant difference regarding side and sex (P > 0.05). In all the specimens, the gracilis was innervated by the anterior branch of the obturator nerve. Blood supply of the gracilis was identified to be derived from 1 single artery in 38 sides of total 80 (47.5%), from 2 arteries in 36 (45%) and from 3 arteries in 6 (7.5%). In 74 sides (92.5%), the nerve was superficial to the main artery, whereas in 6 sides (7.5%), it was deeper. The data of the present study could be beneficial for surgeons in infant surgeries to treat conditions such as obstetrical brachial plexus paralysis, facial palsy, or anal incontinence. Linear functions can be utilized to better evaluate the growth course of the gracilis in fetuses and to predict the dimensions thereof. Additionally, comprehending the structure and recognizing the variations of the gracilis nerves and arteries can help to protect the neurovascular pedicle(s) of the gracilis during the operations.

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PURPOSE: The main objective of this study is to showcase the growth dynamics of levator scapulae, rhomboid major, and rhomboid minor algebraically, to help plan surgeries on newborns and young infants. METHODS: Twenty-five formalin-fixed fetuses (11 male-14 female) with a mean gestational age of 21.80 ± 2.61 (range 18-27) weeks present in the inventory of Mersin University Faculty of Medicine Anatomy Department were dissected. Surface area of levator scapulae, rhomboid major, and rhomboid minor was calculated using digital image analysis software; width and length parameters were measured using digital calipers. RESULTS: Neither sex nor side significant differences were observed in relation with the numerical data of levator scapulae, rhomboid major, and rhomboid minor (p > 0.05). Algebraic parameters such as surface area, width and length were detected to exhibit a linear growth from 18th to 27th week. Linear functions for levator scapulae, rhomboid major and rhomboid minor surface areas were obtained as y = - 136.871 + 10.598 × age (weeks), y = - 480.567 + 33.147 × age (weeks) and y = - 128.090 + 8.843 × age (weeks), respectively. CONCLUSION: The results and data of this study can potentially be beneficial in planning of surgeries for many infancy diseases such as trapezius paralysis, obstetrical brachial plexus palsy, Sprengel's disease, or winged scapula. Linear functions calculated in this study are expected to provide a better understanding of the growth dynamics of levator scapulae, rhomboid major, and rhomboid minor in fetal term and more precise estimation of muscle sizes.

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OBJECTIVE: There is still ongoing research on the relationship of arcuate eminence (AE) and superior semicircular canal (SSC). We aimed to evaluate the precision of predictability of SSC through the morphology of AE via radiological means. MATERIALS AND METHODS: This investigation is performed on 12 dry skulls belonging to Mersin University Medical Faculty department of anatomy. Computed tomography (CT) assessment is performed with 0.5-mm-thin sections temporal bone algorithm on dry skulls which were marked with fixated copper wire by scotch tapes on the most prominent part of the middle fossa floor assuming the location of AE. The data are reformatted on the workstation with vitrea 2.0. The distances of the determined three points including lateral (A), apical (B), and medial (C) of the SSC and the copper wire are measured radiologically. Also, the height between the most apical part of the SSC to the floor of the skullbase (H) is measured. The angles between the placed copper wires and the SSC (E) are calculated. The angle between SSC and the midpoint of the IAC (F) and SSC to the sulcus of the greater GSPN (G) were measured. The nearest distance was measured between the most posterior part of the SSC and the point marked by the perpendicular line drawn from the medial border of the petrous bone to the most posterior part of the internal auditory canal (IAC) (D). RESULTS: The right and left A, B, and C distances are 2.54+/- 2.75, 3.67+/-3.16, 5.85+/-3.77; 2.92+/-2.24, 3.68+/-2.93, 6.09+/-3.40, respectively. We could not find any statistical significance when the right A, B, and C distances were compared with the left values. Examination of the values revealed that C distance is greater than the A distance of the same side both for right (p=0.040) and left (p=0.022) measurements. The calculated left and right E angles are 30.313+/-12.838, and 35.558+/-18.437 degrees, respectively. Statistical significance was not found between the right and left angles. The right and left F, G angles were 53.17, 47.25; 93.58, 100.92 degrees; and D distances are 8.01, 8.13 millimeters, respectively. Statistical significance was not found when right and left E, F, G angles and D distances were compared. Among 12 left and 12 right sides, the copper wire was found to be nearly overlapping to SSC in two in the right and only one in the left. CONCLUSION: This study reveals that there is a great variability predicting the exact location of SSC through the prominence of AE. Complementary studies are needed with greater number of dry skulls and cadavers. Comparison of different hypothesis including the effect of temporal lobe sulcus is to be discussed to better enlighten the exact relationship of the aforementioned anatomical structures.

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OBJECTIVE: The objective of this study was to evaluate the features of flexor hallucis longus (FHL), flexor digitorum longus (FDL) and flexor digitorum accessorius (FDA) muscles with relevance to the tendon grafts and to reveal the location of Master Knot of Henry (MKH). METHODS: Twenty feet from ten formalin fixed cadavers were dissected, which were in the inventory of Anatomy Department of Medicine Faculty, Mersin University. The location of MKH was identified. Interconnections of FHL and FDL were categorized. According to incision techniques, lengths of FHL and FDL tendon grafts were measured. Attachment sites of FDA were assessed. RESULTS: MKH was 12.61 ± 1.11 cm proximal to first interphalangeal joint, 1.75 ± 0.39 cm below to navicular tuberosity and 5.93 ± 0.74 cm distal to medial malleolus. The connections of FHL and FDL were classified in 7 types. Tendon graft lengths of FDL according to medial and plantar approaches were 6.14 ± 0.60 cm and 9.37 ± 0.77 cm, respectively. Tendon graft lengths of FHL according to single, double and minimal invasive incision techniques were 5.75 ± 0.63 cm, 7.03 ± 0.86 cm and 20.22 ± 1.32 cm, respectively. FDA was found to be inserting to FHL slips in all cases and it inserted to various surfaces of FDL. CONCLUSION: The exact location of MKH and slips was determined. Two new connections not recorded in literature were found. It was observed that the main attachment site of FDA was the FHL slips. The surgical awareness of connections between the FHL, FDL and FDA, which participated in the formation of long flexor tendons of toes, could be important for reducing possible loss of function after tendon transfers postoperatively.

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PURPOSE: Although latissimus dorsi (LD) flaps are extensively used in a wide range of interventions, fetus studies on this subject are quite limited. This study aims to obtain detailed information about the morphometric features of LD, thoracodorsal artery (TDA) and nerve (TDN). METHODS: The study was carried out on both sides of 50 formalin-fixed human fetuses (22 male/28 female) with a mean gestational age of 24.5 ± 4.7 (range 18-36) weeks, which were in the inventory of Anatomy Department of Mersin University Faculty of Medicine. Dimensions of LD, lengths and width of TDA and TDN were measured. Surface area of LD was calculated using digital image analysis software. RESULTS: All samples had LD muscle. Neither gender nor side-significant differences were observed in relation with the numerical data of LD, TDN and TDA. Linear function of surface area was calculated as "y = - 1767.532 + 114.582 × Age (weeks)". LD was attached directly to the posterior part of iliac crest in 59 of 100 sides meanwhile in the rest 41, it was attached by the thoracolumbar fascia. TDA gave a branch to serratus anterior in 96 cases and 2 branches in 4 cases. TDN passed superficial to TDA in 84 and deep to TDA in 16 samples. TDN had bifurcation in 93, trifurcation in 6 and tetrafurcation in 1 side. CONCLUSION: Data obtained from this study can be useful for estimating the sizes of LD and related neurovascular structures, especially in neonate surgeries. Linear function of LD surface area can be helpful to design the flap dimensions in newborn surgeries. A throughout knowledge about the branching pattern of TDN and its location-wise relation with TDA should be kept in mind to prevent possible complications during harvesting LD flaps and TDN grafts.

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AIM: The aim of this study was to better define the microsurgical anatomy of the supra/parasellar region and describe variations of the anterior clinoid process (ACP). MATERIAL AND METHODS: Fifteen formalin-fixed cadaver heads and 25 dry skulls were used to define the microsurgical anatomy of the ACP and related structures. The presence of the caroticoclinoid foramen (CaCF) as well as other relevant measurements were all noted. Radiological examination of the CaCF was also demonstrated on dry skulls. RESULTS: Interosseous bridges, which form between the anterior and middle clinoid processes or connect all three (anterior, middle and posterior) clinoid processes, were found in 30% of the specimens. The average basal width, length and thickness of the ACP were 7.3 mm, 9.7 mm and 5.4 mm, respectively. Length of the optic nerve (ON) up to the falciform ligament (FL) was 10.9 mm; length of the ON under the FL was 2.7 mm; length of ON after removal of the ACP and unroofing the optic canal was 21.1 mm. CONCLUSION: This study contributes to the relationship of important vascular, neural, bone and dural layers of this region and also demonstrates the variations of ACP by means of microsurgical dissections and radiological examinations.

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Bilateral variations of renal vessels were encountered during the dissection of a 54-year-old male cadaver. There were triple renal arteries bilaterally, double renal veins on the right, and an unusual formation of renal vein on the left side. A bilateral occurrence of triple renal arteries has not been encountered in the literature, so does an incidence. Additional renal vessels have the potential to cause clinical complications such as hydronephrosis. Their existence has utmost importance in surgical and radiological interventions and radiological examinations.

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PURPOSE: The lack of certain quotable landmarks and not taking the morphometric variations into consideration for mandibular nerve blockade can cause some complications. The aim of this study was to ensure there are data for more feasible and successful lateral extraoral approach to block the mandibular nerve by proposing reliable and quotable landmarks. METHODS: The current study was carried out on 55 skulls at the anatomy departments of the Universities of Mersin and Ankara. The length of the zygomatic arch, measurements indicating the puncture point (PP), injection depth, and injection angle were revealed. The differences between sides and the relationships between the parameters were evaluated by using paired t-test and Pearson correlation test, respectively. RESULTS: Of all skulls, it is observed that the injection line passed anterior to the articular surface of the temporomandibular joint. The distance between external acoustic opening and PP showed positive correlation with the distance between oval foramen and the midpoint of the zygomatic arch on the left side (r = 0.364, P = 0.001). On the right, the correlation was close to the statistically significant level (r = 0.280, P = 0.072). The distance between external acoustic opening and PP that can be adapted to the living subjects was found as 26.31 ± 1.95 mm. Injection angle to the coronal plane was measured to be 16.39 ± 2.96 degrees. The difference between sides for this parameter was not statistically significant. CONCLUSIONS: The determined parameters are suggested to be convenient and quotable to help in successful direct application under three-dimensional computed tomography or computed tomography-fluoroscopy for blocking the mandibular nerve.

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BACKGROUND AND OBJECTIVES: The cerebellar tonsillar herniation occurring in Chiari malformation Type I (CMI) mainly results from overcrowding of a normally developing hindbrain within a primary small posterior cranial fossa (PCF) due to an anomaly in the embryological development of the occipital bone. In the present study, the lengths of PCF parameters were studied in adult CMI patients. PATIENTS AND METHODS: The authors retrospectively examined 15 adult patients with CMI. Multiple measurements were made on magnetic resonance images (MRIs). The results were compared with the findings in 25 controls and 30 dry skulls. RESULTS: Length of the neural structures did not significantly differ between the CMI and the control groups. The average length of the basiocciput was significantly shorter in the CMI group as compared with the control group. The mean length of the supraocciput was significantly shorter and the average diameter of the foramen magnum was significantly longer in the CMI group when compared to the control group and dry skulls. CONCLUSIONS: The morphometric data suggest that, in CMI, a hypoplastic occipital bone, possibly due to the paraxial mesodermal defect of the parachordal plate, causes overcrowding in PCF, which contains the normally developed neural structures.

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