Evaluation of morphological variations of petrotympanic fissure using computed tomography imaging of the temporal bone.

PURPOSE: Petrotympanic fissure (PF) is important for both dentists and otolaryngologists to know the temporal anatomy well especially for pre-surgical radiological evaluations. Computed tomography (CT) is indispensable method for temporal bone imaging. The purpose of this study was to evaluate PF morphology and position using CT. METHODS: CT scans of 300 patients (600 PFs) were retrospectively evaluated. PF types were recorded by dividing into 3 groups (Type 1,2 and 3). Length of the mandibular fossa (MF) and PF, vertical diameter (VD) of the PF at the MF level, midpoint and tympanic cavity (TC) level were measured. PF position types were subdivided as low, midline and high. RESULTS: Type 1, 2 and 3 was found in 18.7%, 51.5% and 29.8% of the cases, respectively. The mean length of the MF and PF was 18.33 mm and 3.77 mm, respectively. The mean VD of the PF at the MF level, midpoint and TC level was 1.71, 0.98 and 0.97 mm, respectively. The low, midline and high position of PF was observed 14.5%, 54.3% and 31.2% of the cases, respectively. CONCLUSION: Length of the MF and PF in males was significantly higher than females. VD of the PF at the MF level in Type 1 and Type 3 was significantly higher than type 2. In type 1,VD of the PF at the midpoint was significantly higher than type 2 and type 3. VD of the PF at the TC level in Type 1 and Type 3 was significantly higher than type 2.

Branching Patterns of Mental Nerve in Newborns.

In classical textbooks of Anatomy, the mental nerve is considered to be the terminal or main branch of the inferior alveolar nerve, especially trifurcate with no designated names as soon as it emerges from the mental foramen. The textbooks define the innervation area of the mental nerve regionally without naming its terminal branches. Nomina Anatomica designates 3 terminal branches of mental nerve as "labial, gingival, and mental branch" but offers no description about their distribution on the mandible. In the present study, bilateral dissections were performed on the lower lip specimens of 20 newborns for 40 mental nerves to determine the branching types of mental nerve. Although anatomy textbooks indicate that mental nerve divides into 3 branches, the authors noted that mental nerve branched into 1, 2, or 3 branches at or right after its exit from the mental foramen. Branching patterns were typed in 13 different subclasses under 3 main groups (Form I-II-III). Moreover, the branching patterns that could not be included in one of these 3 main groups were defined as "Complex Form." The most common type of branching that the authors observed was Form II, which had 2 terminal branches with an incidence of 41.9% (16 specimens). The next frequently encountered type was Form III, having 3 terminal branches, and it was detected in 32.0% of patients (12 specimens). The least common form was Form I, which had 1 terminal branch with a frequency of 15.8% (6 specimens). The unclassified group, Complex Form, was found 10.5% (4 specimens).

Variable morphology of the hyoid bone in Anatolian population: clinical implications:: a cadaveric study / Morfología variable del hueso hioides en una población de Anatolia: consecuencias clínicas: un estudio cadavérico

The variations of the hyoid bone has a great significance for surgical procedures of neck region, and in forensic medicine for evidence of strangulation or hanging, which causes fractures. The aim of this study was to investigate the morphological and morphometrical variations of the hyoid bone in Anatolian population. A total of 60 adult larynx specimens (46 male, 14 female) were dissected to identify morphological and morphometrical variations of hyoid. The infrahyoid muscles and thyrohyoid membrane were cut and ligamentous structures of bone were removed. The variations of shape of the hyoid were classified into six types: A (U-shaped) hyoid bone observed in 31.7 % (19 bones), a horseshoe-H-type in 10 % (6 bones), a B-type hyoid in 31.7 % (19 bones), a D-type hyoid in % 15 (9 bones), a V-type bone in % 5 (3 bones) and HK-type bone in 6.7 % (4 bones) of all necks. The breadth, width and major transverse axis were approximately measured as 40.4 mm, 28.4 mm and 33.5 mm, repectively. It has been found that the hyoid bones of Anatolian population had morphologically important differences than in other populations.To understand the anatomical variations and measurements of this bone is of valuable importance with regard to clinical practice and forensic medicine.

Las variaciones del hueso hioides tiene un gran significado para los procedimientos quirúrgicos de la región del cuello, y en la medicina forense para la evidencia de estrangulación o ahorcamiento que causan fracturas. El objetivo de este estudio fue investigar las variaciones morfológicas y morfométricas del hueso hioides en una población de Anatolia. Un total de 60 muestras de laringe adultas (46 hombres, 14 mujeres) fueron disecadas para identificar las variaciones morfológicas y morfométricas del hueso hioides. Se seccionaron los músculos infrahioideos y la membrana tirohioidea, y fueron removidas las estructuras ligamentosas de los huesos. La forma del hioides se clasificó en seis tipos: a (forma de U) del hueso hioides observó en el 31,7 % (19 huesos), forma de herradura hioides in 10 % (6 huesos), hioides de tipo B en el 31,7 % (19 huesos), tipo D hioides en 15 % (9 huesos), un hueso de tipo V en % 5 (3 huesos) y de tipo HK hueso en un 6,7 % (4 huesos) de todos los cuellos. Se midió la amplitud, ancho y el eje transversal mayor de 40,4 mm, 28,4 mm y 33,5 mm. Determinamos que los huesos hioides de la población Anatolia tenían importantes diferencias morfológicas en comparacion a otras poblaciones. El conocimiento de las variaciones anatómicas y las mediciones de este hueso es importante con respecto a la práctica clínica y la medicina forense.

Bilateral elongated mandibular coronoid process in an Anatolian skull.

Elongation or hyperplasia of coronoid process of mandible is rare condition characterized by abnormal bone development which cause malocclusion and the limited mouth opening. In this study, in an Anatolian skull, a case of bilateral elongation of mandibular coronoid process was presented. Levandoski panographic analysis was performed on the panoramic radiographie to determine the hyperplasia of the coronoid process. The right condylar process was exactly hyperplastic. The measurements of Kr-Go/Cd-Go were 95.10 mm/79.03 mm on right side and 97.53 mm/87.80 mm on left side. The ratio of Kr-Go/Cd-Go on the right side was 1.20. Elongated coronoid process is one of the factors cause mandibular hypomobility, it as reported here might lead to limited mouth opening. The knowledge of this variation or abnormality can be useful for the radiologist and surgeons and prevent misdiagnosis.

Absence of the lateral and third ventricles associated with holoprosencephaly.

We describe a 6-month-old boy suffering from motor and mental retardation. All radiological features were suggestive of holoprosencephaly with no identifiable lateral or third ventricles and fusion of the thalami.

The localization of the asterion according to the anatomical landmarks of posterior cranial fossa in newborns: clinical implications / Localización del asterión de acuerdo con los puntos anatómicos de la fosa craneal posterior en recién nacidos: implicaciones clínicas

The purpose of this study was to determine the localization of the asterion according to the anatomical landmarks of posterior cranial fossa and its relation with sinuses for posterolateral surgical approaches in newborns. On 70 head-halves, a needle about 2 mm with diameter was placed on the centre point of asterion (posterolateral fontanel) by inserting into the whole cranial bony tissue by forming an right angle with the bony surface. Various localizations of asterion and its measurements from the internal and external anatomical landmarks were investigated on term neonatal cadavers. The localization of asterion was found as on the sigmoid-transverse sinus junction (STJ) (5., 6., 7., 8. squares) in 40% of cases on right side and in 34%, on left side. Additionally, it was located below the STJ (9., 10., 11., 12. squares) in 60% of cases, on right side and in 63% of cases on left side. We determined that the most frequent localization of asterion as the 11. square both for the right and left sides 12 (34%) cases for the right side and 11 (31,4%) cases for the left side. The asterion was not located on 1., 2., 3., 4., 5. and 12. squares on right side and 1., 3., 4., 8. and 9. squares on left side. It has been found that the region of asterion has an average distance value of 19.9 mm to internal acoustic meatus (MI), 31.7 mm to posterior clinoid process (PC), 34.4 to dorsum sellae (DS), 19.2 mm to jugular foramen (FJ), 23.0 mm to hypoglossal canal (HC), internally. The distance of asterion as 28.8 mm to zygoma root (ZR) and 22.3 mm to Henle's spine (HS) and 15.8 mm to mastoid tip (MT) and 35.9 mm to external occipital protuberance (PE) were observed. By the guide of point asterion on newborns the area of 1cm2 on this point which was placed on superior 4 squares of our scale diagram is suggested as a safe area of placement of first burr hole to avoid from the risk of bleeding of sigmoid and transverse sinuses on craniotomies of posterior fossa.

El propósito de este estudio fue determinar la localización del asterion de acuerdo con los puntos anatómicos de la fosa craneal posterior y su relación con los senos de abordajes quirúrgicos posterolaterales en los recién nacidos. Fueron utilizadas 70 hemicabezas y se colocó una aguja de alrededor de 2 mm de diámetro en el punto central del asterion (fontanela posterolateral) en todo el tejido óseo craneal produciéndose la formación de un ángulo recto con la superficie ósea. La localización del asterion y las mediciones de los puntos de referencia anatómicos internos y externos fueron investigados en cadáveres de neonatos a término. La localización del asterion se encontró en la unión sinusal transverso sigmoide (STJ) (cuadrados 5., 6., 7., 8.) en el 40% de los casos en el lado derecho y en el 34%, en el lado izquierdo. Además, se encontró por debajo del STJ (cuadrados 9., 10., 11., 12.) en un 60% de los casos en el lado derecho y en el 63% de los casos en el lado izquierdo. Se determinó que la localización más frecuente del asterion fue 11., tanto para los lados derecho e izquierdo, 12 casos (34%) para el lado derecho y 11 casos (31,4%) para el lado izquierdo. El asterion no se encuentra en los cuadrados 1., 2., 3., 4., 5. y 12. del lado derecho y 1., 3., 4., 8. y 9. del lado izquierdo. Se determinó que la región del asterion tiene una distancia promedio de 19,9 mm al meato acústico interno, 31,7 mm al proceso clinoides posterior, 34,4 mm al dorso selar, 19,2 mm al foramen yugular y 23,0 mm al canal hipogloso, internamente. La distancia del asterion a la raíz del hueso cigomático fue 28,8 mm y 22,3 mm a la columna vertebral, siendo de 15,8 mm al proceso mastoides y 35,9 mm a la protuberancia occipital externa. En los recién nacidos, se sugiere un área de 1cm2 y se colocan en 4 casillas superiores de nuestro diagrama a escala, como una zona segura para la realización de la primera trepanación para evitar el riesgo de sangrado de los senos sigmoide y transverso en craneotomías de fosa posterior.

Accessory muscle in the forearm: a clinical and embryological approach.

Muscular variations of the flexor compartment of forearm are usual and can result in multiple clinical conditions limiting the functions of forearm and hand. The variations of the muscles, especially accessory muscles may simulate soft tissue tumors and can result in nerve compressions. During a routine dissection of the anterior region of the forearm and hand, an unusual muscle was observed on the left side of a 65-year-old male cadaver. The anomalous muscle belly arose from the medial epicondyle approxiamately 1 cm posterolateral to origin of normal flexor carpi ulnaris muscle (FCU), and from proximal part of the flexor digitorum superficialis muscle. It inserted to the triquetral, hamate bones and flexor retinaculum. Passive traction on the tendon of accessory muscle resulted in flexion of radiocarpal junction. The FCU which had one head, inserted to the pisiform bone hook of hamate and palmar aponeurosis. Its contiguous muscles displayed normal morphology. Knowledge of the existence of muscle anomalies as well as the location of compression is useful in determining the pathology and appropriate treatment for compressive neuropathies. In this study, a rare accessory muscle has been described.

Bilateral origin of superior cerebellar arteries from the posterior cerebral arteries, and clues to its embryologic basis.

The superior cerebellar artery is the most consistent branch of the basilar artery and arises near the bifurcation of the basilar artery. A bilateral origin of the superior cerebellar arteries from the posterior cerebral arteries has been rarely reported in the literature. Reporting variations in brain vessels is important for neurosurgeons to safely and confidently treat pathologies in this region. We report on a specimen with a bilateral origin to the superior cerebellar artery from the posterior cerebral artery and discuss the embryogenesis of this rare variation.

The termination of superior sagittal sinus and drainage patterns of the lateral, occipital at confluens sinuum in newborns: clinical and embryological implications.

Drainage patterns of dural venous sinuses at confluens sinuum are variable and clinically significant. It has been generally investigated in adults; however, we thought that neonatal cadaver study might be more informative in views of embryological and clinical. A total of 33 skull bases of neonatal cadavers were resected to identify termination patterns of lateral sinus (LS), superior sagittal sinus (SSS) and occipital sinus (OS) at the confluens sinuum. Termination patterns of these sinuses were classified into six types: the SSS showed continuity with right transverse sinus (TS) (with OSs) (30.3%) (Type I); or multiple OSs (21.2%) (Type II). The SSS continued with left TS (with OSs) (12.1% (Type III); or with multiple OSs (6.1%) (Type IV). The SSS shows continuity with both TS (9.1%) (Type V). SSS symmetrically bifurcated, the confluens sinuum has a large OS (21.2%) (Type VI). Understanding of the cerebral venous drainage and large variation of the posterior fossa dural sinuses is crucially important for planning surgical intervention to some tumors in the neck which may require ligation of the internal jugular vein.

Localization of pterion in neonatal cadavers: a morphometric study.

PURPOSE: Pterion is defined as a junction of temporal, frontal, parietal, and sphenoid bones. In newborns, pterion may be defined as a region that shows variability in the exact location because of the lack of complete bony structure. The aim of this study is to define the topographic anatomy of this important surgical point, pterion, and the variability of its localization on craniums of newborn cadavers. METHODS: Our study was performed using 35 term neonatal cadaver specimens. We measured the distances between the pterion and other critical points and used a scale diagram for the definition of pterional area. RESULTS: Our scale diagram showed that pterion is mostly localized in regions c, d, e, and f on the length and regions 2, 3, 4, and 5 on the width. Localization was not observed in regions a, b, g, and h, and in areas of squares 1 and 6. The most observed localization of pterion was the e4 (24.28%) area. CONCLUSION: This study provides a detailed knowledge on localization of this important point, pterion, which will be useful for the clinicians at operation planning and treatment stages, serving for the success in surgery in the presence of this variable topographic cranial anatomy.

Anatomic and arthroscopic study of the medial meniscal horns' insertions.

The insertions of the menisci to the tibia are the most important restraints to extrusion from the knee joint, and are vital for the functional integrity of the menisci. The aim of the present study was to determine variations of tibial insertions of the medial menisci (MM) in newborn cadavers macroscopically and in adults by arthroscopy. Neonatal part of this study was performed on 40 knee joints of 20 Caucasian neonatal cadavers. Adult part was performed on 41 Caucasian adults, whose ages were between 17 and 66 unilaterally by arthroscopy. In neonatal cadavers, according to its insertion, anterior horn of MM was classified in five groups and type 4, in which it was inserted to the transverse ligament, was determined the most frequent one (45%) and posterior horn of MM was classified in three groups and type 3, in which it was inserted to both the posterior intercondylar area of tibia and medial tubercle of intercondylar eminence was determined the most frequent one (50%). In adults, anterior end of MM was most frequently inserted to both anterior intercondylar area of tibia and transverse ligament (76%) and posterior horn of MM was inserted to the posterior intercondylar area of tibia in all of them. This study provides comparative information about insertion of the MM for neonatals and adults, not to evaluate the variants of the insertion of the MM as a tear of the anterior cruciate ligament or a meniscal tear and not to complicate arthroscopy.

The perforating branches of the P1 segment of the posterior cerebral artery.

The perforating branches of the P1 segment of the posterior cerebral artery are vulnerable to injury. Because of their close proximity to the basilar artery, the vulnerability occurs especially during surgical interventions for vascular pathologies such as basilar apex aneurysms. Therefore, extensive knowledge of the microsurgical anatomy of this area is mandatory to prevent poor post-operative outcomes. We microscopically examined 28 P1 segments obtained from 14 adult fresh cadaver brains (6 silicone injected, 8 freshly examined). The P1 segments ranged between 2.8mm and 12.2mm (mean 6.8mm) in length with a mean outer diameter of 1.85 mm (range 0.8-4.5mm). All 94 thalamoperforating branches identified in 27 P1 segments (mean 3.35 branches per segment) arose from the postero-superior aspect of P1 and were the most proximally originating branch in nearly all specimens (96.4%). In addition in 28 P1s, 12 short circumflex arteries (42.8%; mean 0.42 branches per segment), 16 long circumflex arteries (57.1%; mean 0.57 branches per segment) and 10 medial posterior choroidal arteries (35.7%; mean 0.35 branches per segment) were identified and all originated from the posterior or postero-inferior surface of the P1 segment. When the P1 segment had more than one type of branch, it was the short circumflex arteries that were always more proximal in origin than the others. The medial posterior choroidal arteries were always more distal in origin. All three branches were not observed together in any of the P1 segments. The findings in this, and future, anatomical studies may help to reduce the post-surgical morbidity and mortality rates after surgery for posterior circulation aneurysms.

Anatomic variations of the shape of the menisci: a neonatal cadaver study.

Meniscal injuries in children and adolescents are being seen with increased frequency. The menisci are two crescentic lamellae whose functions are to deepen the articular surfaces of the tibial plateu for reception of the condyles of the femur. In our study, our aim is to determine the variations of the shapes and attachments of the menisci in newborns. This study was performed on 11 neonatal cadavers, 22 knee joints that were obtained from the anatomy laboratory. The variations of the shape of the menisci were noted. We found that 77% of the lateral menisci were discoid. This percent is higher than the previously reported percents of the lateral discoid menisci. The different shapes of the menisci were determined as horse shoe, sickle, sided U, sided V and C shaped. We did not determine any discoid medial menisci. We believe that our study will provide support to the neonatal anatomy of the knee, concerning with the surgical procedures and arthroscopy of the knee joint.

Absence of both stapedius tendon and muscle.

During surgery for otosclerosis, it is common for the surgeon to cut the stapedius tendon. The absence of the stapedius muscle with its tendon is uncommon. In this study, we present a case of the absence of the unilateral stapedius tendon and muscle. During dissections of adult temporal bones, the absence of the stapedius tendon and muscle was found in one case. The tympanic cavity was explored with the help of a surgical microscope. The pyramidal process was not developed. A possible ontogenetic explanation was provided. In the presented case, the cause of the anomaly may be failure of the embryological development of the muscle. Awareness of the variations or anomalies of the stapedius muscle and tendon are important for surgeons who operate upon the tympanic cavity, especially during surgery for otosclerosis.

Compensatory brow asymmetry: anatomic study and clinical experience.

To obtain detailed information about the interdigitation between the frontalis muscle and the orbicularis oculi muscle, the authors performed an anatomic study involving 9 cadavers (17 specimens). Three types of interdigitation were recognized. Complete interdigitation was noted in 13 specimens, and partial interdigitation in 13 specimens. In one specimen, there was no interdigitation between the frontalis muscle and the orbicularis oculi muscle. Although most of the specimens showed complete interdigitation between the frontalis muscle and the orbicularis oculi muscle, the interdigitation area exhibited architectural heterogeneity. The study findings provide a basis for a better understanding of compensatory eyebrow ptosis. In addition, two cases supporting the theory that compensatory eyebrow asymmetry may resolve when the palpebral ptosis is treated are presented.

Anatomic variations of the coracoacromial ligament in neonatal cadavers: a neonatal cadaver study.

One of the most common causes of pain and disability in the upper limb is inflammation of the rotator cuff tendons. When no significant bony abnormality exists in the surrounding structures, the coracoacromial ligament has been implicated as a possible cause of impingement on the cuff tendons and various morphological variants of the ligament have so far been claimed to be either the cause or the result of impingement. In this study, 110 shoulders from 60 neonatal cadavers that were preserved in a preparation of formaldehyde were dissected. Anatomic variations of coracoacromial ligaments were investigated with metric and histologic analysis. Three main ligament types were identified: quadrangular, broad band and U-shaped. The multiple banded ligament was not found. Histologic analysis showed that in U-shaped ligaments a thin tissue existed in the central part of the ligament close to the coracoid. Comparing our data with the adult measurements of a previous study we suggest that the primordial ligament is broad shaped, but assumes a quadrangular shape due to the different growth rates of the coracoid and acromial ends. We also suggest that broad and U-shaped ligaments account for the primordial and quadrangular and Y-shaped ligaments account for the adult types of the single or double banded anatomic variants respectively. Our results show that various types of the coracoacromial ligament are present at the neonatal period and that the final shape of the ligament should be defined by developmental factors, rather than degenerative changes.