The Frequency of Occipital Spurs in Relation to the Cephalic Index: An Anatomorphometric Cone Beam CT Study.

BACKGROUND: The occipital spur (OS) can be described as an abnormal elongation of the external occipital protuberance (EOP). The cephalic index (CI) refers to the ratio of width to length in any skull. AIM: The aim of the present study was to evaluate the frequency and types of OS. It also aimed to determine the mean CI and the distribution of skull types using cone beam computed tomography (CBCT). And to determine if there was a relationship between the cephalic index and the presence and types of OS. METHODS: CBCT scans from 523 patients were included in the study. OSs were classified as type 1 (flat), type 2 (crest), and type 3 (spine). Skull length and width were measured on axial sections and the CI was calculated. Based on the cephalic index (CI), skull types were classified as dolichocephalic (CI < 75), mesocephalic (75 < CI < 80), brachycephalic (80 < CI < 85), and hyperbrachycephalic (CI > 85). RESULTS: The most common cranial types in the study group were brachycephalic (44.7%), mesocephalic (28.3%), hyperbrachycephalic (21.2%), and dolichocephalic (5.7%). Regarding the presence of OS, 54.3% of the participants had no OS, 23.1% had flat type, 15.3% had crest type, and 7.2% had spin type OS. There was a statistically significant difference (P < 0.05) in the frequency of OS according to skull type. CONCLUSION: This study, the first to evaluate CI and OS using CBCT, concludes that brachycephaly is the most common cranial type. OS is more common in mesocephalic and dolichocephalic skulls, at older ages, and in males.

Computed Tomography-Based Occipital Condyle Morphometric Analysis in the Turkish Population: A Trajectory Analysis for Optimal Screw Selection.

AIM: To provide a comprehensive analysis for accurate screw size selection and insertion angle during surgical procedures. MATERIAL AND METHODS: In this retrospective study, a total of 120 patients participated, resulting in the analysis of 240 occipital condyles using coronal, sagittal, and axial planes on CT scans. Statistical evaluation was performed using the Wilcoxon rank-sum test, with p < 0.05 considered statistically significant. RESULTS: The mean sagittal length and height were measured at 17.2 ± 1.7 mm and 9.1 ± 1.5 mm, respectively. The average condyle angle, a crucial factor for screw insertion, was assessed at 38.0 ± 5.5 mm in length, 19.6 ± 2.6 mm in width, and 9.5 ± 1.0 mm in height. Condyle height in the anterior and posterior hypoglossal canals was measured at 10.8 ± 1.4 mm and 9.0 ± 1.4 mm, respectively. Screw angle and condyle width were statistically smaller in females compared to the male population. CONCLUSION: The OC is a significant anatomical structure in the craniovertebral junction, playing a crucial role in stability. The obtained morphological values are applicable to the Turkish population and offer statistically significant findings for preoperative planning involving occipital condyle screw instrumentation.

Osseous bridging of the condylar fossa: report of a rare anatomical variation at the outer skull base.

PURPOSE: The topic of osseous variations of the craniocervical junction is a complex morphological and embryological chapter of human anatomy, with a possible impact on neurogical and vascular functionality in this morphological variable region. MATERIAL & METHODS: An until now undescribed anatomical variation of the exoccipital part of the occipital bone has been observed after maceration at the outer skull base of a West-European 68-year-old male body donor. RESULTS: On both sites of the foramen magnum accessory osseous processes were observed that arise from the jugular process and point towards the lateral margin of the foramen magnum. On the left site this process forms a full arc that bridges the condylar fossa completely. CONCLUSION: The observed osseous bridge over the condylar fossa has not been reported on before and can be explained by the partial persistence of a primordial vertebra between atlas and occipital bone: the Proatlas. The resulting accessory structure may affect due to its topographic conditions the V3-Segment of the vertebral artery and its accompanying nerves, and thus, play a role in diagnosis and therapy of vascular and/or neurological symptoms of head and neck.

Prevalence and Morphometry of Occipital Foramen in Dry Skulls and its Clinical Implications.

The occipital emissary foramen (OEF) located on the occipital bone transmits the occipital emissary vein, which connects the occipital vein to the confluence of cranial venous sinuses. The OEF varies in incidence, number, size, and location. Knowledge of this foramen is essential for carrying out suboccipital and transcondylar surgeries without clinical implications. Hence, the study was planned. The aim of the present study is to elaborate on incidence, location, and morphometry consisting of the number and size of this foramen in light of clinical bearing in the context of the Indian population. The study was carried out in the Department of Anatomy using 80 skulls of unknown age and sex. The occipital bone of the skull was observed for the incidence, number, size, and location of the occipital emissary vein and associated clinical implications were elaborated. The incidence of occipital foramen was 36.25% and detected in 29 skulls. All these occipital foramina were patent. The mean diameter of this foramen was 0.6 mm. The most common location of these foramina was the left side of the foramen magnum, followed by the left side of the external occipital crest. The information about the incidence, number, size, and location of OEF is important to prevent catastrophic bleeding during surgery in the region of the occipital bone. The awareness of differential morphometry and morphology of occipital foramina is of great importance for neurosurgeons during suboccipital craniotomy and skull base surgeries, including far lateral and transcondylar approaches to access posterior cranial fossa for management of pathologies in the cranial cavity.

Morphological and morphometric anatomy of the lesser occipital nerve and its possible clinical relevance.

The lesser occipital nerve (LON) has one of the most variations among occipital nerves. We aimed to investigate morphological and morphometric features of LON. A total of 24 cadavers, 14 males (58%) and 10 females (42%), were dissected bilaterally. LON was classified into 3 types. The number of branches and the perpendicular distances of the point where LON emerged from the posterior border of sternocleidomastoid muscle to vertical and transverse lines passing through external occipital protuberance were determined. The shortest distance between LON and great auricular nerve (GAN), and linear distance of LON to its branching point were measured. The most common variant was Type 1 (30 sides, 62.5%), followed by Type 2 (12 sides, 25%) and Type 3 (6 sides, 12.5%), respectively. In males, Type 1 (22 sides, 78.6%) was the most common, while Type 1 (8 sides, 40%) and Type 2 (8 sides, 40%) were equally common and the most common in females. On 48 sides, 2-9 branches of LON were observed. The perpendicular distance of said point to vertical and transverse lines was meanly 63.69 ± 11.28 mm and 78.83 ± 17.21 mm, respectively. The shortest distance between LON and GAN was meanly 16.62 ± 10.59 mm. The linear distance of LON to its branching point was meanly 31.24 ± 15.95 mm. The findings reported in this paper may help clinicians in estimating the location of the nerve and/or its branches for block or decompression surgery as well as preservation of LON during related procedures.

Anatomy of the craniocervical junction - A review.

An in-depth understanding of the anatomy of the craniocervical junction (CCJ) is indispensable in skull base neurosurgery. In this paper, we discuss the osteology of the occipital bone, the atlas (C1) and axis (C2), the ligaments and the muscle anatomy of the CCJ region and their relationships with the vertebral artery. We will also discuss the trajectory of the vertebral artery and review the anatomy of the jugular foramen and lower cranial nerves (IX to XII). The most important surgical approaches to the CCJ, including the far lateral approach, the anterolateral approach of Bernard George and the endoscopic endonasal approach, will be discussed to review the surgical anatomy.

Hypoglossal canal: an osteological and morphometric study on a collection of dried skulls in an Italian population: clinical implications.

BACKGROUND: The hypoglossal canal is a dual bone canal at the cranial base near the occipital condyles. The filaments of the hypoglossal nerve pass through the canal. It also transmits the meningeal branch of the ascending pharyngeal artery, the venous plexus and meningeal branches of the hypoglossal nerve. The hypoglossal nerve innervates all the intrinsic and extrinsic muscles of the tongue except the palatoglossal and is fundamental in physiological functions as phonation and deglutition. A surgical approach to the canal requires knowledge of the main morphometric data by neurosurgeons. METHODS: The present study was carried out on 50 adult dried skulls: 31 males: age range 18-85 years; 19 females: age range 26-79 years. The skulls came from the ''Leonetto Comparini'' Anatomical Museum. The skulls belonged to people from Siena (Italy) and its surroundings (1882-1932) and, therefore, of European ethnicity. The present study reports (a) the osteological variations in hypoglossal canal (b) the morphometry of hypoglossal canal and its relationship with occipital condyles. One skull had both the right and left hypoglossal canals occluded and, therefore, could not be evaluated. None of the skulls had undergone surgery. RESULTS: We found a double canal in 16% of cases, unilaterally and bilaterally in 2% of cases. The mean length of the right and left hypoglossal canals was 8.46 mm. The mean diameter of the intracranial orifice and extracranial orifice of the right and left hypoglossal canals was 6.12 ± 1426 mm, and 6.39 ± 1495 mm. The mean distance from the intracranial end of the hypoglossal canal to the anterior and posterior ends of occipital condyles was 10,76 mm and 10,81 mm. The mean distance from the intracranial end of the hypoglossal canal to the inferior end of the occipital condyles was 7,65 mm. CONCLUSIONS: The study on the hypoglossal canal adds new osteological and morphometric data to the previous literature, mostly based on studies conducted on different ethnic groups.The data presented is compatible with neuroradiological studies and it can be useful for radiologists and neurosurgeons in planning procedures such as transcondilar surgery. The last purpose of the study is to build an Italian anatomical data base of the dimensions of the hypoglossal canal in dried skulls..

Retrospective evaluation of the morpometric and morphological anatomy of the occipital condyle, hypoglossal canal and foramen magnum in Turkish populaton with CBCT.

PURPOSE: The aim of this study is to morphometrically and morphologically examine the occipital condyle, which is an important anatomical region in terms of surgery and forensic medicine, and its surrounding structures, to evaluate the change in mean values according to gender and age, and to evaluate the correlation of the measurements obtained. METHODS: 180 (90 men, 90 women) CBCT images selected from the archive of Ankara University Faculty of Dentistry. Occipital Condyle length and width, Hypoglossal Canal-Basion distance, Hypoglossal Canal-Opistion distance, Hypoglossal Canal-Occipital Condyle anterior and posterior border distance, Occipital Condyle thickness, Hypoglossal Canal length, the widest diameter of Hypoglossal Canal, the narrowest diameter of the Hypoglossal Canal, the length of the Jugular Tubercle, the width of the Jugular Tubercle, the anterior intercondylar distance, the posterior intercondylar distance, and the Foramen Magnum index were measured. At the same time, the presence of septum or spicule in the hypoglossal canal and protrusion of the occipital condyle were evaluated. The relationship of age, gender, anterior and posterior intercondylar distance, and foramen magnum index measurements with all measurements were examined. RESULTS: In our study, all measurements were repeated 1 month after the first measurements to evaluate the intra-observer agreement, and the agreement between the obtained measurements and the first measurements was evaluated by calculating the intraclass correlation coefficient and 95% confidence intervals. Men's measurements were found to be significantly higher than women's measurements. When the coefficients of concordance in all measurements were examined, it was observed that there was a perfect concordance. CONCLUSION: When the results of the study are evaluated, it is seen that the values ​​obtained are generally close to the studies related to CT. Considering this, an idea can be gained as to whether CBCT, which has a lower dose and less cost, can be used as an alternative to CT in studies to be conducted with more comprehensive and different methods in skull base surgical planning.

Surgical anatomy of hypoglossal canal for various skull base surgeries.

PURPOSE: Anatomical knowledge of the hypoglossal canal is very important in relation to drilling of occipital condyle, jugular tubercle etc. So, this study was conducted to identify various morphometric and morphological features of the hypoglossal canal and its distance from adjacent structures relative to stable and reliable anatomic landmarks. METHODS: The study was performed on 142 hypoglossal canals of 71 adult human dry skulls. The parameters measured were the transverse, vertical diameter, depth of the hypoglossal canal. The distances from the hypoglossal canal to the foramen magnum, occipital condyle and jugular foramen were also noted. In addition, the different locations of the hypoglossal canal orifices in relation to the occipital condyle were assessed. The different shapes and types of the hypoglossal canal were also noted. RESULTS: There was significant difference (p < 0.05) in measurements taken on the right and left sides in males and females. The intracranial orifice of hypoglossal canal was present in middle 1/3rd in 100% of occipital condyle for both genders. The extracranial orifice of the hypoglossal canal was found to be in the anterior 1/3rd in 99% and 93.7% for male and female, respectively. Simple hypoglossal canal with no traces of partition was found to be more in males and females. The most common shape noted was oval both in males and females (71.8% and 68.7% respectively). CONCLUSION: The results of the dimensions of the hypoglossal canal and its distance from other bony landmarks will be helpful for neurosurgeons to plan which surgical approaches should be undertaken while doing various surgeries in posterior cranial fossa.

External occipital protuberance classification with special reference to spine type and its clinical implications.

PURPOSE: This investigation aimed to study the types of external occipital protuberance (EOP) with special reference to Type 3 (spine type). Detailed information will be useful for clinicians to manage occipital headaches or issues related to the biomechanics of the neck and for accurate radiological interpretations. METHODS: Thirty-one dry intact cadaveric skulls were studied for EOP classification. In Type III EOP cases, the size of EOP was noticed using different modalities and compared. The superior nuchal lines and external occipital crest were observed for their prominence and any variation. RESULTS: 42% of the skulls belong to Type 1, 51.5% to Type 2, and 6.5% to Type 3 EOP. Superior nuchal lines and external occipital crest were more prominent in Types 2 and 3 EOP. In Type 3 EOP cases, the mean length, width, and thickness of the spine as measured directly on the skull were 16.63 mm; 20.1 mm, and 7.82 mm respectively, the same as radiograph findings. CT examination revealed the average volume as 0.95 cm3. Out of two Type 3 EOP cases, the spine with larger values for its size was having a lesser volume value in CT. CONCLUSIONS: Plain lateral radiography is a reliable method to measure the length and thickness of spinous EOP. However, more values of these parameters for morphometry of the EOP spine do not mean more volume of EOP and vice versa. Detailed information regarding the occurrence of occipital spur and its morphology will be of great importance to neurosurgeons, sports, physicians, emergency departments, and radiologists.

Classification of Endoscopic Transnasal Lateral Skull Base Approaches: Anatomical Study.

OBJECTIVE: Endoscopic transnasal approaches (ETAs) to the ventrolateral skull base are commonly classified according to coronal planes or anatomical structures. Our goal is to simplify the description of the ETA to lateral skull base regions in a sequential dissection with correlation to computed tomography, helping in preoperative planning and efficient surgical exposure, and exposing the surgical anatomy limitations. METHODS: Five freshly injected cadaver heads were dissected using an extended ETA to the lateral skull base. Each specimen underwent a high-resolution computed tomography scan. A classification of the lateral skull base based on well-defined zones was proposed. RESULTS: We divided the lateral target into four different zones, in a craniocaudal orientation: zone 1 is the space lying between the orbital floor superior and the level of the sellar floor inferior, zone 2 is on the coronal plane, located between the level of the sellar floor and the vidian canal, zone 3 is the area lateral to the anterior limb of the petro-occipital fissure, located between the vidian canal and the carotid canal, and zone 4 is the space located between the carotid canal and the extracranial opening of the hypoglossal canal, lateral to the anterior part of the posterior limb of petro-occipital fissure. CONCLUSIONS: Multiple previous works have described and classified the coronal plane and its lateral extensions. Our classification system for the proposed lateral zones enables preoperative planning to select a suitable approach. The craniocaudal orientation facilitates the understanding of surgical corridors and tailored exposure.

Radiologic Evaluation of the Fossa Navicularis on Dry Skull: A Comparative CBCT Study.

Fossa navicularis (FN) is defined as bony depression that is not always present and is located anterior to the foramen magnum and pharyngeal tubercle on the inferior aspect of the basilar part of the occipital bone. It has been reported that FN can create an infection spread path from the pharynx to the intracranial structures. Therefore, the diagnosis of this variation is important. Although cone beam computed tomography (CBCT) diagnostic accuracy has mostly been verified in detection and quantification particularly on human skulls, there is no study comparing morphometric measurements between direct measurement on the skull and CBCT measurement. The main object of this study is to evaluate the presence of FN on dry bones and CBCT images of the same dry skull and to examine the morphometric and morphological features of this formation. Thirty-two random craniums that were made available for this study that did not have any fractures or deformities of the cranial base were examined. The sagittal diameter, transverse diameter, and depth of the FN was measured both directly on dry skulls and radiologically on CBCT images of dry skull. In addition, the shape of FN (SFN) was determined. FN was detected in 10 (31.25%) of 32 craniums examined with both modalities. It was determined that sagittal diameter of the FN, transverse diameter of the FN, depth of the FN, and the shape of FN did not show a statistically significant difference between the 2 measurements. Unlike the literature, FN was investigated on dry bones both directly and in CBCT images in this study. In contrast to previously thought the FN may be smaller according to this findings, and this small variation can be detected with CBCT images. According to this findings, it can be said that morphometric evaluations on CBCT are accurate and reliable, and CBCT is a safe method for clinical diagnosis and treatment.

Resection of Condylar Skull Base Tumor via Combined Far Lateral and Infrajugular Approaches with Single-Stage Occipitocervical Fusion.

Epithelioid hemangioma is a rare vascular mesenchymal tumor with a paucity of reports of cranial involvement. In particular, guidance on treatment for lateral skull base lesions is lacking, despite this being a highly technically challenging location. Nuances in the management decisions for this tumor type are discussed. Two major challenges with this location are proximity to critical neurovascular structures and managing secondary craniocervical instability. We present a patient with a lateral skull base epithelioid hemangioma treated with transcondylar resection, single-stage occipitocervical fusion, and adjuvant radiation and chemotherapy. The patient consented to both the procedure and the published report of her case including imaging. Obtaining tissue was necessary for diagnosis. Maximal safe resection, resection of a tumor such that the greatest clinical benefit is achieved with the minimum risk, was favored given the location and vascularity of the lesion. Occipitocervical fusion was recommended given ongoing bony destruction by the tumor and further expected iatrogenic instability upon resection. This was performed as a single stage given expected need for postoperative adjuvant radiation therapy and dynamic neck pain (Video 1). Surgical planning and decision making are detailed, including rationale and potential risks and benefits. We discuss positioning, equipment needs, and the importance of a multidisciplinary surgical team. Park bench positioning was used for part 1, left-sided extended far lateral and infratemporal fossa presigmoid approaches. For part 2, occipitocervical fusion, the patient was transitioned to prone position. The anatomy is highlighted in labeled pictures of the approach and dissection, and surgical video is presented for key surgical steps. Preoperative and postoperative imaging is analyzed. A desirable clinical outcome was obtained.

Sexual dimorphism and biomechanical loading in occipital bone morphological variation.

We explore the contribution of biological sex and biomechanical activity from subsistence to occipital bone variation. Previous studies have used occipital bone traits to determine biological sex and identify ancestry to differing degrees of success. Biomechanical stress from variation in subsistence and gender-based divisions of labor could perhaps explain some of the noise in the signal for these grouping variables. To explore this possibility, we used metric (foramen magnum length and breadth, external occipital protuberance depth, lambda-inion length, bicondylar breadth) and nonmetric traits (general occipital form, presence of a nuchal crest, and nuchal line count). We collected original data and mined published data for our analysis using skeletal collections of Native American hunter-gatherers and horticulturalists, a historic military site, and contemporary study collections. We find that the foramen magnum area exhibits sexual dimorphism and is not influenced by subsistence, but the accuracy of sex estimation is only 71%, suggesting the chance of being correct at slightly more than two-thirds. All traits exhibited sex-based variation but only bicondylar breadth and lambda-inion metrics exhibited subsistence-based variation. Given the limited amount of variance explained by either sex or sex and subsistence, biomechanics may still play a role but not from the influence of subsistence practices in these datasets. Additional data from a wider array of skeletal samples, perhaps with known occupation, is warranted if we are to understand how occipital variation is shaped.

Reappraisal of the types of hypoglossal canal: endocranial approach.

This study aims to classify the endocranial variations inside the Hypoglossal Canal (HC) and evaluate the elements of the HC region in terms of sizes, diameters, and distances to the nearby surgical landmarks. The present study was done on 18 adult human fixed cadaver heads bilaterally. The internal opening of HC was examined for the presence of dural or osseos septations in the canal and was classified into five types (Type 1-5). The dimensions of hypoglossal nerve (CN XII) and the distance of intracranial openings of HC from the jugular foramen and jugular tubercle were measured. The prevalence of endocranial HC types were determined on both sides as follows: type 1 (23.53% left, 6.25% right), type 2 (37.5% right, 5.88% left), type 3 (52.94% left, 25% right), type 4 (18.75% right, 17.65% left), type 5 (12.5% right). Understanding the endocranial HC types is crucial for neurosurgeons in the differential diagnosis of various intracranial pathologies for the posterior cranial fossa approach. Knowing the anatomical relationships between the adjacent structures and symmetrical organization of the HC according to the types is crucial in determining surgical strategies and preserving adjacent structures.

The Forgotten Intermediate Condylar Canal: Anatomic Study with Application to Skull Base Surgery.

BACKGROUND: The intermediate condylar canal, which lies lateral to the occipital condyles and medial to the jugular foramen, is rarely mentioned in textbooks, even those devoted to the skull base. Therefore the present anatomic study was performed to better elucidate these structures. METHODS: We studied 100 adult skulls (200 sides) to better understand the prevalence and anatomy of the intermediate condylar canal. RESULTS: An intermediate canal was found on 6 of 200 sides (3%). On average, these canals traveled 7.1 mm lateral to the occipital condyle and had a mean of 2.2 mm posteromedial to the jugular foramen. Anteriorly, these canals opened into the external surface of the hypoglossal canal and, when present, were just medial to a paracondylar process for which there was a strong positive correlation. The length of the canals ranged from 5 to 7.8 mm. In all, there were 3 partial canals and 3 complete canals. One left canal communicated anteriorly at the confluence of the inferior opening of a septated (bifurcated) hypoglossal canal and an unnamed foramen medial to the jugular foramen. These canals were distinct from posterior condylar canals when the latter was present. CONCLUSIONS: Knowledge of the anatomic variants at the base of the skull may help minimize complications during surgical procedures that employ a paracondylar or transcondylar approach or approaches to the jugular foramen.

Morphometric assessment methods for estimation of sexual dimorphism from cranial occipital condyles / Métodos de evaluación morfométrica para la estimación del dimorfismo sexual de los cóndilos occipitales craneales

SUMMARY: Identification of fragmentary human remains is an integral par of medico legal investigations. Occipital region is commonly not affected in traumatic injuries and accidents due to its secluded position which makes it the integral part in determination of sex in the absence of entire skeleton. Occipital condylar region is also the most common area for degenerative and neoplastic diseases. So thorough knowledge of anatomy of occipital condyle is very essential during surgical interventions. 86 skulls were studied from osteological collections of Department of Anatomy, Yenepoya Medical College. Maximum length and breadth of the occipital condyle, anterior intercondylar distance and posterior intercondylar distance was measured with the help of vernier callipers. Descriptive statistics was calculated for the parameters considered. Metric data of right and left sides were compared with student t test and p value was calculated.All data obtained was subjected for discriminant function analysis to derive the statistical model. All the measurements were significantly high in males compared to females. Condylar length and width, anterior and posterior intercondylar distance can be used to derive formula for determination of sex in south Indian population with an accuracy of 66.3 %.

RESUMEN: La identificación de restos humanos fragmentarios es una parte integral de las investigaciones médico legales. La región occipital comúnmente no se ve afectada en lesiones traumáticas y accidentes debido a su posición apartada que la convierte en parte integral en la determinación del sexo en ausencia de un esqueleto completo. La región condilar occipital es también el área más común de enfermedades degenerativas y neoplásicas. Por lo tanto, el conocimiento integral de la anatomía del cóndilo occipital es esencial durante las intervenciones quirúrgicas. Se estudiaron 86 cráneos de colecciones osteológicas del Departamento de Anatomía, Facultad de Medicina de Yenepoya. Se midió el largo y ancho máximo del cóndilo occipital, la distancia intercondilar anterior y la distancia intercondilar posterior con la ayuda de un calibrador vernier. Se calculó la estadística descriptiva para los parámetros considerados. Los datos métricos de los lados derecho e izquierdo se compararon con la prueba t de Student y se calculó el valor de p. Todos los datos obtenidos se sometieron a análisis de función discriminante para derivar el modelo estadístico. Todas las medidas fueron significativamente altas en los hombres en comparación con las mujeres. La longitud y el ancho del cóndilo, la distancia intercondilar anterior y posterior se pueden utilizar para derivar la fórmula para determinar el sexo en la población del sur de la India con una precisión del 66,3 %.

Frequency of enlarged external occipital protuberance and its association with age and sex: a cross-sectional CT scan study / Frecuencia de la protuberancia occipital externa agrandada y su asociación con la edad y el sexo: un estudio de tomografía computarizada transversal

SUMMARY: External occipital protuberance (EOP) is a midline bony protrusion in the occipital bone, the significance of which has gained recent attention in the medical community. Our present study aims to assess the average size of EOP in a Jordanian cohort and its relation to age and sex, while determining the frequency of enlarged EOP in this cohort. The present study was a cross-sectional study that was carried out in a referral hospital in Jordan. We reviewed thousands of CT scans taken with dedicated bone window imaging during the last two years, beginning January 2018. Measurements were taken by trained radiology residents and were then further reviewed by radiology specialists. An EOP was classified as enlarged (EEOP) if it exceeded 10 mm. A total of 4409 patients, 2265 (51.4 %) females and 2144 (48.6 %) males, met our inclusion criteria. Their mean age was 54.1 ? 22.2 years. The mean size of the EOP in these patients was 8.4 ? 4.2 mm (range: 0-56 mm). Out of the 4409-study population, 1210 (27.4 %) presented with EEOP. The prevalence of an EEOP was significantly higher in the male population (33.6 %) when compared with the female population (21.6 %) (P < 0.001). The size of the EOP was also significantly related to the age of the patient, with EEOP increasing with increasing age. The mean size of EOP in our Jordanian cohort was 8.4 ? 4.2 mm. The frequency of enlarged EOP was found to be 27.4 % in our cohort, and was significantly more common in males and in older patients.

RESUMEN: La protuberancia occipital externa (POE) es una protuberancia ósea localizada en el plano mediano del hueso occipital, cuya importancia recientemente ha ganado atención en la comunidad médica. Este estudio tuvo como objetivo evaluar el tamaño promedio de POE en una cohorte jordana y su relación con la edad y sexo, mientras se determina la frecuencia de POE aumentada en este grupo. Se llevó a cabo un estudio transversal en un hospital de referencia en Jordania. Revisamos miles de imagenes radiológicas en tomografía computarizada y visualización de ventanas durante los últimos dos años, a partir de enero de 2018. Las mediciones fueron tomadas por residentes de radiología, y luego revisadas por especialistas en radiología. Un POE se clasificó como aumentado (POEA) si superaba los 10 mm. Un total de 4409 pacientes, 2265 (51,4 %) mujeres y 2144 (48,6 %) hombres, cumplieron con nuestros criterios de inclusión. La edad media fue de 54,1 ? 22,2 años. El tamaño medio del POE en estos pacientes fue de 8,4 ? 4,2 mm (rango: 0-56 mm). De la población del estudio 4409, 1210 (27,4 %) presentaron POEA. La prevalencia de una POEA fue significativamente mayor en la población masculina (33,6 %) en comparación con la población femenina (21,6 %) (P <0,001). El tamaño del POE también se relacionó significativamente con la edad del paciente, aumentando el POEA con la edad. El tamaño medio de POE en nuestra cohorte jordana fue de 8,4 ? 4,2 mm. Se encontró que la frecuencia de aumento de POE en nuestra cohorte fue del 27,4 % y fue significativamente más común en hombres y en pacientes mayores.

The Ligamentum condylicum posterius as a precursor structure of the Processus condylicus posterior, another Proatlas-Manifestation of the human occipital bone.

This article presents the results of a dissection series investigating a previously neglected ligamentous structure attached to the human occipital bone, the Ligamentum condylicum posterius or posterior condylar ligament, and relates these results to the manifestation of a likewise poorly recognized occipital bony variation, the Processus condylicus posterior. The dissection of 50 human cranio-cervical junctions revealed the existence of the posterior condylar ligament in 98% of all cases, sometimes containing free elongated ossicles and osseous spurs at the insertion points at the occipital bone. In two cases the osseous formation of a Processus condylicus posterior became apparent (4%), which further provided the opportunity to study the behaviour of the ligament in these cases. In this article, we show and discuss that the posterior condylar ligament and osseous structures possibly derive from tissue that originates from the material of the dorsal arch of the Proatlas, a rudimentary vertebra between occipital bone and atlas. For this purpose, the Ponticulus atlantis posterior as another Proatlas-manifestation, whose origin from the dorsal Proatlas-arch is widely accepted in literature, is considered. This bony variant was found in 11 specimens (22%) in the present study and further served to classify and interpret the findings of the much rarer Processus condylicus posterior. As a result of this dissection series and a review of literature on this understudied topic, a typology of manifestations of the posterior condylar ligament, Processus condylicus posterior and related structures like free ossicles has been introduced.