External Occipital Protuberance Research Articles

Localization of the Greater Occipital Nerve Through Palpation of Bony Landmarks: A Cadaveric Study

Objective:to provide anatomic confirmation that standard methods which practitioners skilled in palpation use, can reliably identify the most likely site of emergence of the greater occipital nerve in most patients. The location and frequency of subcutaneous emergence of the greater occipital nerve and occipital artery with respect to the external occipital protuberance-mastoid line are reported. Methods:The external occipital protuberance and the mastoid processes were identified by palpation bilaterally on 57 body donors and the medial trisection point of a line connecting these bony landmarks was identified. A 4cm circular dissection guide divided into 4 quadrants was centered on the trisection point and used to guide the removal of a circle of skin. The in-situ location of the nerve and artery were exposed by deep dissection within the circle. The frequency of the emergence and occurrence of the nerve and artery by quadrant were analyzed. ResultsIn 114 total dissections the greater occipital nerve was found to emerge within the circle 96 times (84%) and the occipital artery 100 times (88%). The nerve (90%) and artery (81%) emerged from the two inferior quadrants most of the time with no difference noted between male and female donors. The greater occipital nerve and occipital artery were found to emerge together most commonly in inferior lateral quadrant. Branches of the nerve and artery traveled together most frequently through the two lateral quadrants. ConclusionThis study confirmed that the medial trisection point of the external occipital protuberance-mastoid line can be located via palpation and reliably used to pinpoint the subcutaneous emergence of the greater occipital nerve and occipital artery in most individuals. When relying on palpation alone to identify the trisection point in the clinic, infusion of nerve block inferior and lateral to this point is most likely to bathe the greater occipital nerve in anesthetic.

Use of bone landmarks for assessing the safety of acupuncture on the posterior midline of the neck region

ObjectiveMany acupuncture acupoints are located on the posterior midline of the neck region. The needling depth for acupuncture is important for practitioners, and an unsafe needling depth increases the possibility of damage to the spinal cord and brainstem. Can the safety of acupuncture be assessed by examining bone structures? We focused on this aim to carry out this study.MethodsThe shortest distance from the posterior border of the foramen magnum to the line joining both upper ends of the posterior border of the mastoid process was measured on 29 skulls. Distances from the posterior border of the vertebral foramen to the tip of the spinous process and posterior tubercle of the atlas were measured and evaluated from 197 dry cervical vertebrae and 31 lateral cervical radiographs of patient subjects. The anatomic relationships of the vertebral canal with the external occipital protuberance, tip of the spinous process of the axis, tip of the posterior tubercle of the atlas, and upper end of the posterior border of the mastoid process were observed and evaluated via lateral cervical radiography.ResultsThe shortest distance from the foramen magnum to the line between the mastoid processes was 4.65±1.75 mm, and the distance from the superior border of the vertebral foramen of the atlas to the posterior tubercle was less than the distance from the inferior border. The distance from the superior border of the vertebral canal to the tip of the spinous process in C2-C7 was greater than the distance from the inferior border. The mean lengths of the superior border of the C2 spinous process and the inferior border of the C7 spinous process were greater than 21 mm and 31 mm, respectively. The line from the upper end of the posterior border of the mastoid process to the tip of the C2 spinous process or 10 mm deep to the tip of the C2 spinous process was posterior to the vertebral canal.ConclusionsOn the posterior midline of the neck region between the tip of spinous process of axis and external occipital protuberance, if the needle reaches the depth of the line between the upper end of posterior border of mastoid process and the tip of the spinous process of the axis, approximately 10 mm along the spinous process of the axis, the needle is in the safe region. The mean length of the C2-C7 spinous process is suitable to accommodate the needling depth of the adjacent acupoint. Bone structures can be used to effectively assess the safety of acupuncture on the posterior midline of the neck region.

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.

The triangular area between the greater, lesser, and third occipital nerves and its possible clinical significance.

Occipital Neuralgia (ON) is defined as a unilateral or bilateral pain in the posterior area of the scalp occurring in the distribution area or areas of the greater occipital nerve (GON), lesser occipital nerve (LON), and/or third occipital nerve (TON). In the present study, the purpose was to show the possible importance of the triangular area (TA) in nerve block applied in ON by measuring the TA between GON, TON, and LON. A total of 24 cadavers (14 males, 10 females) were used in the present study. The suboccipital region was dissected, revealing the points where the GON and TON pierced the trapezius muscle and superficial area, and the point where the LON left the sternocleidomastoid muscle from its posterior edge and was photographed. The area of the triangle between the superficial points of these three nerves and the center of gravity of the triangle (CGT) were determined by using the Image J Software and the results were analyzed statistically. The mean TA values were 952.82 ± 313.36 mm2 and 667.55 ± 273.82 mm2, respectively in male and female cadavers. Although no statistically significant differences were detected between the sides (p > 0.05), a statistically significant difference was detected between the genders (p < 0.05). The mean CGT value was located approximately 5cm below and 3-3.5cm laterally from the external occipital protuberance in both genders and sides. In ON that has more than one occipital nerve involvement, all occipital nerves can be blocked by targeting TA with a single occipital nerve block, and thus, the side effects that may arise from additional blocks can be reduced. The fact that there was a statistically significant difference according to the genders in the TA suggests that different block amounts can be applied according to gender.

Determination of skull variation in Akkaraman and Kangal Akkaraman sheep by geometric morphometric method

Sheep breeding has an important place in the world and in Turkey, as sheep are farm animals that provide most of their nutritional needs from pasture, have good adaptability and are low in cost. Akkaraman sheep and the Kangal Akkaraman sheep, which was considered its sub-variety until 2012, constitute half of the sheep population in Turkey. In this study, morphometric diversity between the skulls of Akkaraman and Kangal Akkaraman breed sheep was examined by geometric morphometric method. 2D images obtained from 3D models of 24 male sheep skulls from two different provinces were analyzed using 10 landmarks from dorsal and lateral views. The results from the dorsal view, the first three principal components (PC1, PC2 and PC3) accounted for a total of 64.13% of the morphological variation and the largest changes in are associated with external occipital protuberance, midline nasofrontal suture and rostral edge of the incisive fissure. From the lateral view, three first principal components explained the morphological variation 27.56%, 22.32% and 10.65% respectively. In the comparison of the skull morphology of Akkaraman and Kangal Akkaraman sheep from dorsal and lateral views, no allometric components were identified, as most of the described shape variations were not size-dependent. As a result of these analyses, more detailed information was obtained about the shape differences of the skull. Geometric morphometric analysis is successful in detecting differences in skull shape of different sheep breeds and can be successfully used for classification.

Cervical Range of Motion Assessment through Inertial Technology: A Validity and Reliability Study

Inertial technology has spread widely for its comfortable use and adaptability to various motor tasks. The main objective of this study was to assess the validity of inertial measurements of the cervical spine range of motion (CROM) when compared to that of the optoelectronic system in a group of healthy individuals. A further aim of this study was to determine the optimal placement of the inertial sensor in terms of reliability of the measure, comparing measurements obtained from the same device placed at the second cervical vertebra (C2), the forehead (F) and the external occipital protuberance (EOP). Twenty healthy subjects were recruited and asked to perform flexion–extension, lateral bending, and axial rotation movements of the head. Outcome measurements of interest were CROM and mean angular velocities for each cervical movement. Results showed that inertial measurements have good reliability (0.75 &lt; ICC &lt; 0.9). Excellent reliability (ICC &gt; 0.9) was found in both flexion and right lateral bending angles. All parameters extracted with EOP placement showed ICC &gt; 0.62, while ICC &lt; 0.5 was found in lateral bending mean angular velocities both for F and C2 placements. Therefore, the optimal sensor’s positioning emerged to be EOP. These results suggest that inertial technology could be useful and reliable for the evaluation of the CROM.

Modified interfacet technique using shaped autologous occipital bone mass for basilar invagination

PurposeIn economically undeveloped areas, surgery for basilar invagination (BI) is still a serious economic burden for people. This study introduces a modified interfacet technique for the treatment of BI using shaped autologous occipital bone mass to reduce BI and to save economical expenditure. MethodsThe data of 6 patients with BI who underwent modified interfacet technique using shaped autologous occipital bone mass in our hospital from April 2020 to February 2021 were retrospectively analyzed. During the operation, osteotomy at the external occipital protuberance was performed using ultrasonic osteotome, followed by interfacet release and implantation of shaped autologous occipital bone mass to complete vertical reduction. The atlantodental interval (ADI), Chamberlain's line violation (CLV), clivo-axial angle (CXA) and cervico-medullary angle (CMA) were compared before and after surgery. Additionally, we observed implant stability during the follow-up period to assess the long-term success of the modified interfacet technique. ResultsThe surgical procedure was successful in all six patients, with no reported incidents of vascular injury, spinal cord injury, or dural tear. Following the operation, improvements were observed in the ADI, CLV, CXA, and CMA. Throughout the follow-up period, the implants remained stable, demonstrating no complications such as bone resorption of the autologous occipital bone mass, implant fracture, or displacement. ConclusionThe utilization of shaped autologous occipital bone mass in atlantoaxial interfacet bone grafting has demonstrated effectiveness and feasibility. This technique offers simplicity, ease of preparation, and cost-effectiveness, making it a viable option for treating BI.

Can exostoses of the external occipital protuberance and superior nuchal lines cause headache? A report of two cases

Compression of the occipital nerves can cause occipital headache. Several potential compression points have been identified along their course. One of these points is the hitherto undescribed instance of exostoses of anatomic structures of the occipital bone. A 34-year-old man with a prominent external occipital tuberance and superior nuchal lines complained of headache in the area of distribution of the greater occipital nerve with tenderness near the bony protrusion on palpation. A 44-year old woman experienced stabbing pain in the lateral orbital region with pressure on the ossified insertion of the ipsilateral trapezius muscle near the external occipital protuberance. Local nerve block achieved temporary relief of pain. Exostosis of the external occipital protuberance and superior nuchal lines may impinge on the greater and third occipital nerves. The characteristics of the pain in our cases differ in some aspects from those of occipital neuralgia.

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

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. 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. 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 16.63mm; 20.1mm, and 7.82mm 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. 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.

Morphometric Evaluation of Occipital Artery

Objective: Occipital artery anatomy should be well known in order to minimize complications that may occur in the occipital artery, which is closely adjacent to this nerve, during greater occipital nerve blockade. In this study, it is aimed to evaluate the morphometric relationship of the occipital artery with neighboring anatomical structures in order to prevent damage during clinical applications. Materials and Methods: This study was carried out using CTA images of the head and neck region of patients who applied to Balikesir University Medical Faculty Training and Research Hospital for various reasons between 2015 and 2021. In the study, CTA images of 85 individuals aged 35-63 years were evaluated morphometrically using Radiant DICOM viewer 64-bit computer software. The obtained data were transferred to SPSS Version 25 software and analyzed quantitatively. Results: According to the results obtained from the study, no significant difference was found between the variables and genders. As the age of the individual increased, it was observed that the left occipital artery was located more inferolateral to the external occipital protuberance. As a result of the data obtained, a negative correlation was observed between the closest distance between the right OA-ML and the right EOP-ML and the spinous process of the seventh cervical vertebra. Conclusion: In line with the average values obtained as a result, it is thought that an injection to the central point of the triangular area, which is formed as a result of combining the reference points in the posterior occiput, may be safer in order to protect the occipital artery.

Topographic and anatomical relationships of the lower jaw and auricle in human prenatal ontogenesis

Aim to describe the topographic and anatomical relationships of the fetal lower jaw and auricle in the mid-gestation period.&#x0D; Material and methods. The 110 mandibles of human fetuses of the second trimester were selected for the study and divided into groups by sex and age. The morphological techniques and the method of ultrasound scanning were used to determine the topographic relationships of the lower jaw and the fetal ear, the location of the central part of the auricle relative to the lower jaw (the line connecting the gnathion point and the external occipital protuberance) at different age periods.&#x0D; Results. During the mid-gestation period, with the growth of the fetus, the auricle normally shifts upward relative to the mandible. At the beginning of the study period, the auricle is located just below the angle of the lower jaw. Its central part (C) is below the line (AB) connecting the gnathion point and the external occipital protuberance. The perpendicular from the conditional center of the auricle to the line AB is half the diameter of the auricle 3.7 1.1 mm. In the second age group, the auricle is located at the level of the branch and angle of the lower jaw Its conditional center (C) is below the line AB and is of the diameter of the auricle 3.1 0.8 mm. By the end of the mid-gestation period, the auricle is displaced to the level of the processes of the lower jaw above the notch. Its central part is above line AB, the perpendicular from point C to line AB is 6.1 1.4 mm.&#x0D; Conclusion. The deviations in the formation of the topographic and anatomical relationships of the lower jaw and auricle of the fetus from 14 to 27 weeks of gestation can be additional criteria for the development of congenital fetal pathology and require the fetoabnormal alertness.

Occipital spur: an incidental finding on a diagnostic cone-beam computed tomography – a case report

Exaggerated bony outgrowth of the external occipital protuberance is called occipital spur. The current report presents a case of a 20-year-old male patient seeking orthodontic treatment. The patient was referred for a cone-beam computed tomography scan to determine the position of impacted maxillary canines. An incidental finding on the scan was the existence of a focal spine-like hyperostosis in the occipital protuberance, and confirmed to be an occipital spur (Type III spine form). Clinical examination showed a palpable bone swelling without any tenderness, infection or discharge. He was referred to an orthopaedic surgeon should any symptoms get aggravated in the future. This case supports the essential role of cone-beam computed tomography to detect, analyse and identify the lesion as an occipital spur. This is the first such case report of its kind, which measures the size of occipital spur using cone-beam computed tomography and 3D imaging software. Usually asymptomatic, awareness of this uncommon presentation can expedite emergency medical care in the event of pain, or trauma leading to fracture or avulsion of the spur fragment. In such an event, the readily available CBCT data will be indispensable to surgeons for planning surgery with precise linear and volumetric measurements. Knowledge of these bony spurs is of untold value to anatomists, who will benefit greatly from being able to study the variants in vivo, in addition to studies on dry skulls or preserved cadavers. It is also of interest to clinicians and radiologists for diagnostic purposes, and sports physicians.

Morphometric evaluation of great vein of Galen and its clinical implications.

The Galenic venous system plays a vital role in the drainage of blood from deeper parts of the brain. This venous system is contributed by many major veins. These veins are located closer to the pineal gland making the surgical approach in this region difficult. Any accidental injury or occlusion of the vein of Galen could lead to devasting results. Thus, studying the dimensions of the vein of Galen is more important. Hence, we aimed to evaluate the morphometry and trajectory to the vein of Galen. About 100 computed tomographic venography records were evaluated and the length, diameter of vein of Galen, angle between straight sinus and vein of Galen and distance from internal occipital protuberance and roof of fourth ventricle to vein of Galen were studied. The mean length and diameter of vein of Galen were 9.8±2.7 and 4.08±1.04 respectively. The mean angle between straight sinus and vein of Galen was 64.2°. The mean distance between external occipital protuberance and roof of fourth ventricle to vein of Galen were 52±6.9 and 33.3±4.5 respectively. No significant morphometric differences were observed between the age groups as well as between the sexs. The results obtained from this study may be helpful for the neurosurgeons in better understanding of the anatomy of the Galenic venous system and to adopt a safe surgical approach to improve the efficacy of the surgeries of the pineal gland and also in the region of vein of Galen.

Anatomical dimensions and variances of the foramen ovale in adult human skulls

Background/Aim: The foramen ovale (FO) is very important in neurosurgical approaches; however, studies and developments in the literature report that no definite consensus about the cannulation of the FO is available. Therefore, more morphometric information concerning the FO is needed in addition to the previously defined morphological and morphometric features. The aim of this study was to compare the features of the foramen ovale stated in the literature and to analyze the topographic relationship between the FO and the anatomical structures around it to determine its precise location. Methods: The study included 70 sides from 35 dry skulls of unknown age and gender. Skulls with any deformity or pathology that would affect the measurements were not included in the study. All skulls were placed in the horizontal plane with the external occipital protuberance facing posteriorly, the piriform aperture facing anteriorly, and the skull base pointing upwards at a 90° angle after which it was photographed vertically with the length scale. A Nikon D5300 Digital Camera was used for the photography, and digital image processing software (Image J) was used for foramen ovale measurements. In addition, the shape of the foramen ovale was classified as oval, almond, D-shaped, slit-shaped, round, and irregular. SPSS 21.0 was used for the statistical analysis. Results: The mean anteroposterior diameter length of the FO was 6.144 mm, and the transverse diameter length was 2.885 mm. When the distribution of the shape of the FO was examined, oval and almond shapes were most common shapes (34.29%). In addition, round (12.85%), D-shaped (10%), and slit-shaped (8.57%) were obtained. According to Pearson’s correlation analysis, the highest correlation was between the distance from the carotid canal to the foramen ovale and the shortest distance from the foramen ovale to the midline (FO-CC and the FO-ML, respectively; r = 0.427). Conclusion: The morphology of the FO is important in terms of surgical and interventional approaches. In the literature, no significant differences between the right and left sides for the foramen ovale were found in contrast to our study. When the FO shape percentages were examined in most previous studies, it was seen that most of them were oval. In this study, the ratios of oval and almond shapes were the same. Morphometric measurements can give different results in every race due to the structure of the bones, which may vary according to the population. We think that presenting data on the Turkish population in this study will set an example for conducting future studies.

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.

Computed Tomographic Study of Occipital Thickness in Ethnic Malays.

Introduction:Occipitocervical fusion is performed to address craniocervical and atlantoaxial instability. A screw of at least 8mm is needed for biomechanical stability. Occipital thickness of Malay ethnicity is unknown, and this study presents the optimal screw placement positions for occiput screw in this population. This was a retrospective cross-sectional study of 100 Malays who underwent computed tomography (CT) scan for brain assessment. To measure the occipital bone thickness of Malay ethnicity at the area of common screw placement for occipitocervical fusion. The subject’s data was obtained from the institutional database with consent from the administrations and the patients. None of the patients had any head and neck pathology.Materials and methods:The subject’s data was obtained from the institutional database with consent from the administrations and the patients. None of the patients had any head and neck pathology. Computed tomography (CT) of 100 Malay patients who underwent head and neck CT were analysed, based on our inclusion and exclusion criteria. Measurements were taken using a specialised viewer software where 55 points were measured, followed a grid with 10mm distance using external occipital protuberance (EOP) as the reference point.Results:There were 57 males and 43 females of Malay ethnicity with a mean age of 36.7 years analysed in this study. The EOP was the thickest bone of the occiput which measured 16.15mm. There was an area of at least 8mm thickness up to 20mm on either side of the EOP, and at level 10mm inferior to the EOP. There is thickness of at least 8mm, up to 30mm inferior to the EOP at the midline. The males have significantly thicker bone especially along the midline compared to females.Conclusion:Screws of at least 8mm can be safely inserted in the Malay population at 20mm on either side of the EOP at the level 10mm inferior to the EOP and up to 30mm inferior to the EOP at the midline.

Correlation of the external occipital protuberance with venous sinuses: a magnetic resonance imaging study.

To date, no study has explored the external occipital protuberance (EOP) using neuroimaging modalities. This study aims to characterize them using magnetic resonance imaging (MRI). A total of 96 patients underwent thin-sliced, post-contrast MRI. The sagittal images were analyzed. In 97%, the EOPs were delineated as a focal external protrusion of the midline region of the occiput with varying morphologies. In 89% of 93 patients with identifiable EOPs, parts of the intracranial dural sinuses were found to lie just below the inion, the most prominent point of the EOP. The most frequently targeted dural sinus was the confluence of sinuses that was found in 57%, followed by the superior sagittal sinus. In 16%, a bony foramen and transmitting vessel were detected in the EOP, connecting between the diploic channels and the subcutaneous veins. Furthermore, in 33%, bony foramina and transmitting venous structures were identified in the region just below the EOPs, connecting between the diploic channels and the subcutaneous veins. The intracranial dural venous sinus is located just below the EOP with a high probability. Most bony foramina in the EOP and midline suboccipital region may transmit veinous structures connecting to the diploic channel.

Prenatal and early post-natal development of the skull in Nigerian breeds of sheep: a gross anatomical study

The aim of this study was to bridge the gap of information on the gross morphology of the skull of sheep foetuses. A total of 240 samples consisting of fetal and day-old Balami, Uda and Yankasa breeds were used; the skulls were prepared using chemical maceration technique. In the 1st trimester, no visible ossifications were observed on the skull. In the 2nd trimester, ossification of the frontal, parietal, occipital and basisphenoid bones were observed. The nasal bones were ossified, but concaved in Balami and flat in Uda and Yankasa. In the 3rd trimester, an interparietal bone developed between the parietal and occipital bones. The paracondyloid processes, occipital squamous, and the external occipital protuberance were developed in the 3rd trimester. The interparietal bone appeared paired in Yankasa but unpaired in Balami and Uda, which developed into a paired bone in the day-old. In the day-old, the orbital walls were completely fused except in the Uda; the formation of the cornual process began; the presphenoid of the Yankasa was developed. It was concluded that grossly, ossification was observed in the 2nd trimester and it began with the neurocranial bones, however, in the 2nd trimester, the skull was partly soft and pliable and the foramina were rudimentary. In the 3rd trimester, the skull bones were hard and osseous. All the bones on the dorsal surfaces of the skull were membranous whereas some of the bones of the ventral surface were cartilaginous in origin.

Prenatal and early post-natal development of the skull in Nigerian breeds of sheep: a gross anatomical study

The aim of this study was to bridge the gap of information on the gross morphology of the skull of sheep foetuses. A total of 240 samples consisting of fetal and day-old Balami, Uda and Yankasa breeds were used; the skulls were prepared using chemical maceration technique. In the 1st trimester, no visible ossifications were observed on the skull. In the 2nd trimester, ossification of the frontal, parietal, occipital and basisphenoid bones were observed. The nasal bones were ossified, but concaved in Balami and flat in Uda and Yankasa. In the 3rd trimester, an interparietal bone developed between the parietal and occipital bones. The paracondyloid processes, occipital squamous, and the external occipital protuberance were developed in the 3rd trimester. The interparietal bone appeared paired in Yankasa but unpaired in Balami and Uda, which developed into a paired bone in the day-old. In the day-old, the orbital walls were completely fused except in the Uda; the formation of the cornual process began; the presphenoid of the Yankasa was developed. It was concluded that grossly, ossification was observed in the 2nd trimester and it began with the neurocranial bones, however, in the 2nd trimester, the skull was partly soft and pliable and the foramina were rudimentary. In the 3rd trimester, the skull bones were hard and osseous. All the bones on the dorsal surfaces of the skull were membranous whereas some of the bones of the ventral surface were cartilaginous in origin.

Neanderthal child's occipital from Baume Moula‐Guercy (Soyons, Ardèche, France)

AbstractObjectivesThis article provides an ontogenetically based comparative description of two immature occipital fragments from Baume Moula‐Guercy (MIS 5e) and examines their affinities to European and Middle Eastern Middle‐to‐Late Pleistocene (≈MIS 14–MIS ≈ 1) Homo.Materials and methodsDescription of the M‐S‐41 and M‐S‐61 occipital fragments (≈6–8 years) is based on observations of original fossils, casts, CT scans, literature descriptions, and virtual ectocranial and endocranial reconstructions. Our ontogenetically based sample represents a Preneanderthal‐Neanderthal group and a Homo sapiens group. These groups are subdivided into (1) Preneanderthals (≈MIS 14–9), Early Neanderthals (MIS 7–5e), and Late Neanderthals (MIS 5d‐3), and (2) Middle (MIS 5), Upper (MIS 3–1), and Late (MIS ≈ 1) Paleolithic H. sapiens. Measurements and developmental age determinations follow standard techniques.ResultsBased on the M‐S‐41/M‐S‐61 composite, the strongly convex upper occipital scale flattens into the vertical suprainiac fossa, as in immature Early Neanderthals. A doubled suprainiac fossa expressing a weakly developed bounding torus and pocking of the central region is typical of immature Neanderthals. The transverse torus is thickened medially, lacks significant lateral development, has a laterally placed protuberance, and is concave medially. A linear (triangular) tubercle, as opposed to an external occipital protuberance, is present. An occipital bun is absent.DiscussionThe occipital remains from Moula‐Guercy make a substantial contribution to the record of Neanderthal cranial evolution because immature Early Neanderthal occipitals are rare, fragmentary, and likely represent only two paleodemes (Krapina, La Chaise‐de‐Vouthon). The Moula‐Guercy occipital possesses characteristics well‐established in European Neanderthals by MIS 7, and it is most similar to the occipitals of other Early Neanderthals.