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Child's Nervous System : ChNS :... Apr 2011The embryology of the bony craniovertebral junction (CVJ) is reviewed with the purpose of explaining the genesis and unusual configurations of the numerous congenital... (Review)
Review
BACKGROUND
The embryology of the bony craniovertebral junction (CVJ) is reviewed with the purpose of explaining the genesis and unusual configurations of the numerous congenital malformations in this region. Functionally, the bony CVJ can be divided into a central pillar consisting of the basiocciput and dental pivot and a two-tiered ring revolving round the central pivot, comprising the foramen magnum rim and occipital condyles above and the atlantal ring below. Embryologically, the central pillar and the surrounding rings descend from different primordia, and accordingly, developmental anomalies at the CVJ can also be segregated into those affecting the central pillar and those affecting the surrounding rings, respectively.
DISCUSSION
A logical classification of this seemingly unwieldy group of malformations is thus possible based on their ontogenetic lineage, morbid anatomy, and clinical relevance. Representative examples of the main constituents of this classification scheme are given, and their surgical treatments are selectively discussed.
Topics: Atlanto-Occipital Joint; Humans; Occipital Bone
PubMed: 21193993
DOI: 10.1007/s00381-010-1358-9 -
Biological Reviews of the Cambridge... Jun 2020The origin and evolution of the vertebrate skull have been topics of intense study for more than two centuries. Whereas early theories of skull origin, such as the... (Review)
Review
The origin and evolution of the vertebrate skull have been topics of intense study for more than two centuries. Whereas early theories of skull origin, such as the influential vertebral theory, have been largely refuted with respect to the anterior (pre-otic) region of the skull, the posterior (post-otic) region is known to be derived from the anteriormost paraxial segments, i.e. the somites. Here we review the morphology and development of the occiput in both living and extinct tetrapods, taking into account revised knowledge of skull development by augmenting historical accounts with recent data. When occipital composition is evaluated relative to its position along the neural axis, and specifically to the hypoglossal nerve complex, much of the apparent interspecific variation in the location of the skull-neck boundary stabilizes in a phylogenetically informative way. Based on this criterion, three distinct conditions are identified in (i) frogs, (ii) salamanders and caecilians, and (iii) amniotes. The position of the posteriormost occipital segment relative to the hypoglossal nerve is key to understanding the evolution of the posterior limit of the skull. By using cranial foramina as osteological proxies of the hypoglossal nerve, a survey of fossil taxa reveals the amniote condition to be present at the base of Tetrapoda. This result challenges traditional theories of cranial evolution, which posit translocation of the occiput to a more posterior location in amniotes relative to lissamphibians (frogs, salamanders, caecilians), and instead supports the largely overlooked hypothesis that the reduced occiput in lissamphibians is secondarily derived. Recent advances in our understanding of the genetic basis of axial patterning and its regulation in amniotes support the hypothesis that the lissamphibian occipital form may have arisen as the product of a homeotic shift in segment fate from an amniote-like condition.
Topics: Animals; Anura; Biological Evolution; Birds; Cervical Vertebrae; Extinction, Biological; Fossils; Hypoglossal Nerve; Mammals; Neck; Occipital Bone; Phylogeny; Reptiles; Skull; Spinal Canal; Urodela; Vertebrates
PubMed: 31912655
DOI: 10.1111/brv.12578 -
PloS One 2021To investigate three-dimensional morphological variation of the occipital bone between sexes and among populations, to determine how ancestry, sex and size account for...
OBJECTIVES
To investigate three-dimensional morphological variation of the occipital bone between sexes and among populations, to determine how ancestry, sex and size account for occipital shape variation and to describe the exact forms by which the differences are expressed.
METHODS
CT data for 214 modern crania of Asian, African and European ancestry were compared using 3D geometric morphometrics and multivariate statistics, including principal component analysis, Hotelling's T2 test, multivariate regression, ANOVA, and MANCOVA.
RESULTS
Sex differences in average occipital morphology are only observed in Europeans, with males exhibiting a pronounced inion. Significant ancestral differences are observed among all samples and are shared by males and females. Asian and African crania have smaller biasterionic breadths and flatter clivus angles compared to Europeans. Asian and European crania are similar in their nuchal and occipital plane proportions, nuchal and occipital angles, and lower inion positions compared to Africans. Centroid size significantly differs between sexes and among populations. The overall allometry, while significant, explains little of the shape variation. Larger occipital bones were associated with a more curved occipital plane, a pronounced inion, a narrower biasterionic breadth, a more flexed clivus, and a lower and relatively smaller foramen magnum.
CONCLUSIONS
Although significant shape differences were observed among populations, it is not recommended to use occipital morphology in sex or population estimation as both factors explained little of the observed variance. Other factors, relating to function and the environment, are suggested to be greater contributors to occipital variation. For the same reason, it is also not recommended to use the occiput in phylogenetic studies.
Topics: Asian People; Black People; Female; Humans; Imaging, Three-Dimensional; Male; Models, Anatomic; Occipital Bone; Sex Characteristics; Skull; Tomography, X-Ray Computed; White People
PubMed: 33444349
DOI: 10.1371/journal.pone.0245445 -
Orthopaedic Surgery Jun 2020Occipitocervical fusion (OCF) is an effective treatment for instability of occipitocervical junction (OCJ). The occipital condyle screw serves as a novel surgical...
OBJECTIVES
Occipitocervical fusion (OCF) is an effective treatment for instability of occipitocervical junction (OCJ). The occipital condyle screw serves as a novel surgical technique for occipitocervical fixation. However, the intraoperative procedures for the occipital condyle screw technique have relied on surgeons' experience, so the pool of surgeons who are able to perform this surgery safely is limited. The present study aims to evaluate the feasibility and safety of the occipital condyle screw technique using human cadavers and to provide image anatomy for clinical application basis.
METHODS
The scientific study comprised 10 fresh-frozen cadaveric specimens from the anatomy department of Qingdao University. Placement of the occipital condyle screws (3.5 mm diameter and 20.0 mm length) was performed in the 10 fresh-frozen cadaveric specimens with intact occipitocervical junctions, respectively. Occipitocervical CT was performed for all specimens and the DICOM data was obtained. Occipitocervical CT three-dimensional (3D) reconstruction was performed for the cadavers. Morphometric analysis was performed on the bilateral occipitocervical junction of 10 cadaveric specimens based on the 3D reconstruction CT images. Detailed morphometric measurements of the 20 occipital condyles screws were conducted including the average length of the screw trajectory, inside and upper tilting angles of screws, distance to the hypoglossal canal, and to the medial wall of occipital condyle.
RESULTS
Placement of the occipital condyle screws into the 20 occipital condyles of the 10 cadaveric specimens was performed successfully and the trajectory of implantation was satisfactory according to 3D CT reconstruction images, respectively. There was no obvious injury to the spinal cord, nerve root, and vertebral artery. The length of the bilateral screw trajectory was, respectively, 20.96 ± 0.91 mm (left) and 20.59 ± 0.77 mm (right) (t = 1.306, P > 0.05). The upper tilting angle of bilateral screws was, respectively, 11.24° ± 0.74° (left) and 11.11° ± 0.64° (right) (t = 0.681, P > 0.05). The inside tilting angle of bilateral screws was, respectively, 31.00° ± 1.32° (left) and 30.85° ± 1.27° (right) (t = 0.307, P > 0.05). The screw's distance to the bilateral hypoglossal canal was, respectively, 4.84 ± 0.54 mm (left) and 4.70 ± 0.54 mm (right) (t = 0.685, P > 0.05). The screw's distance to the medial wall of the bilateral occipital condyle was, respectively, 5.13 ± 0.77 mm (left) and 5.04 ± 0.71 mm (right) (t = 0.384, P > 0.05).
CONCLUSION
The occipital condyle screw technique can serve as a feasible and safe treatment for instability of the occipitocervical junction with meticulous preoperative planning of the screw entry point and direction based on individual differences. Morphometric trajectory analysis is also an effective way to evaluate the surgical procedure.
Topics: Bone Screws; Cadaver; Cervical Vertebrae; Feasibility Studies; Humans; Imaging, Three-Dimensional; Joint Instability; Occipital Bone; Spinal Fusion; Tomography, X-Ray Computed
PubMed: 32495510
DOI: 10.1111/os.12700 -
European Spine Journal : Official... Feb 2010
Topics: Atlanto-Occipital Joint; Bone Screws; Cervical Atlas; Female; Gait Disorders, Neurologic; Humans; Internal Fixators; Joint Instability; Middle Aged; Occipital Bone; Postoperative Complications; Prosthesis Implantation; Spinal Cord Compression; Spinal Fusion; Treatment Outcome; Wounds and Injuries
PubMed: 20130929
DOI: 10.1007/s00586-010-1303-3 -
AJNR. American Journal of Neuroradiology Aug 1994To describe the CT findings in occipital condyle fractures in patients suffering craniocervical trauma. (Review)
Review
PURPOSE
To describe the CT findings in occipital condyle fractures in patients suffering craniocervical trauma.
METHODS
Six occipital condyle fractures in five patients were analyzed. Because of clinical or plain-film findings, the craniocervical junction in each patient was imaged using thin-section, high-resolution CT. Axial data were reformatted in the coronal plane or in both coronal and sagittal planes. Clinical and radiologic findings associated with occipital condyle fractures reported in the English medical literature were correlated with our cases to determine conclusive predictive features indicating condylar injury.
RESULTS
Two avulsion (type III) fractures in two patients, two compression (type I) fractures in one patient, and two compression fractures in two patients were diagnosed by CT. Specific predictive features indicating occipital condyle fracture could not be confirmed.
CONCLUSIONS
CT greatly facilitates diagnosing and typing of occipital condyle fractures. Nonspecific parameters promoting CT after trauma are unexplained persistent upper-neck pain with normal plain-film findings, lower cranial nerve palsies, spasmodic torticollis, retropharyngeal or prevertebral soft-tissue swelling, and fractures of the atlas or axis.
Topics: Cervical Vertebrae; Humans; Neurologic Examination; Occipital Bone; Skull Fractures; Spinal Cord Compression; Tomography, X-Ray Computed
PubMed: 7976943
DOI: No ID Found -
Anatomical Record (Hoboken, N.J. : 2007) Nov 2022The basioccipital bone is an essential developmental component to the occipital bone, occipital condyles, foramen magnum, clivus, and cranial base. The basioccipital...
The basioccipital bone is an essential developmental component to the occipital bone, occipital condyles, foramen magnum, clivus, and cranial base. The basioccipital bone joins each exoccipital bone with a basiexoccipital synchondrosis and the basisphenoid/sphenoid bone with a spheno-occipital synchondrosis. The basioccipital is found intermediate to the petrous temporal bones and forms the bilateral petrooccipital/petroclival fissures otherwise known as the petrooccipital complex. Thus, the basioccipital bone is a central component to the developing cranial base. Despite the importance of basioccipital development in cranial ontogeny, there has been limited study of basioccipital ontogeny. This study assessed 98 disarticulated human basioccipital bones from a perinatal population ranging in age-at-death from 5-months intrauterine to 5-months post-natal development. Size and shape of basioccipital bones were assessed with traditional and extended eigenshape geometric morphometric analysis. The results of this study demonstrate that the basioccipital bone grows in width at a faster rate than it grows in length. The maximum basioccipital width surpassed the midsagittal length at approximately 7-months intrauterine development. Canonical variate analysis revealed statistically significant shape change occurring from a relatively narrow/elongate (anterior-to-posterior) basiocciput shape with mild concavity at the foramen magnum in the fifth and sixth intrauterine months to a relatively broad/stout basiocciput shape with more pronounced concavity in the postnatal months. Likewise, growth rate in total length was greater than midsagittal length, demonstrating enlargement of concavity in the anterior foramen magnum over time. This report provides insight into cranial development and aids in estimating age-at-death among fetuses and infants.
Topics: Female; Fetus; Humans; Infant; Infant, Newborn; Occipital Bone; Pregnancy; Skull Base; Sphenoid Bone
PubMed: 34825511
DOI: 10.1002/ar.24838 -
Scientific Reports Mar 2024The 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...
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.
Topics: Male; Female; Humans; Clinical Relevance; Peripheral Nerves; Occipital Bone; Neck Muscles; Cadaver
PubMed: 38462647
DOI: 10.1038/s41598-024-55648-8 -
Folia Morphologica 2022The foramen magnum (FM) is an important landmark because of its close relationship to key structures such as the brainstem and spinal cord, an extension of the medulla...
BACKGROUND
The foramen magnum (FM) is an important landmark because of its close relationship to key structures such as the brainstem and spinal cord, an extension of the medulla oblongata. Because of the similarity in their shape, the existence of a relationship between cranial length and anteroposterior diameter of the FM, and between cranial width and transverse diameter of the FM may reveal the magnificent harmony of the skull and FM. Based on this idea, we investigated the existence of this harmony in skulls that we used in our study.
MATERIALS AND METHODS
In this study, 60 adult dry skulls belonging to the Turkish population were examined. The anteroposterior and transverse diameters of the foramen magnum and the length and width of the skull were measured. Measurements were made directly on the skull using a digital sliding calliper. New indices and ratios were applied with those measurements.
RESULTS
Our study suggests that FM width and FM length could be estimated by using the cranial length and cranial width measurements in the skull by accepting the mean of these coefficients (4.62) as the golden ratio. The average of the coefficients of cranial width to FM width ratio (4.62 ± 0.35 [95% CI: 4.52-4.70]) and the average of the coefficients of cranial length to the FM length ratio (4.62 ± 0.50 [95% CI: 4.49-4.76]) were found to be equal to each other. In order to check the accuracy of this hypothesis, FM width and FM lengths were estimated with the help of new equations.
CONCLUSIONS
In the present study, the ratio between the anteroposterior and transverse diameters of both FM and the cranium was estimated at 4.62, indicating a magnificent harmony between cranial and subcranial structures. With this ratio, it is easy to estimate FM's size based on simple cranial measurements.
Topics: Foramen Magnum; Head; Pilot Projects; Skull; Spinal Cord
PubMed: 33634836
DOI: 10.5603/FM.a2021.0018 -
Operative Neurosurgery (Hagerstown, Md.) Jun 2021Pediatric occipitothoracic fusion can be challenging because of small size pedicles and thin occipital bone. Three-dimensional (3D) printing technology can help with...
BACKGROUND
Pediatric occipitothoracic fusion can be challenging because of small size pedicles and thin occipital bone. Three-dimensional (3D) printing technology can help with accurate screw insertion but has not been described for occipital keel plate positioning so far.
OBJECTIVE
To describe the novel use of 3D technology to position occipital keel plates during pediatric occipitothoracic fixation.
METHODS
A young boy with segmental spinal dysgenesis presented with asymmetrical pyramidal paresis in all limbs. Developmental abnormities of the cervical spine caused a thinned spinal cord, and because of progressive spinal cord compression, surgical intervention by means of occipitothoracic fixation was indicated at the age of 3 yr.Because of the small-size pedicles and thin occipital bone, the pedicle screws and occipital plates were planned meticulously using 3D virtual surgical planning technology. The rods were virtually bent in order to properly align with the planned screws. By means of 3D-printed guides, the surgical plan was transferred to the operating theater. For the occipital bone, a novel guide concept was developed, aiming for screw positions at maximal bone thickness.
RESULTS
The postoperative course was uneventful, and radiographs showed good cervical alignment. After superimposing the virtual plan with the intraoperative acquired computed tomography, it was confirmed that the occipital plate positions matched the virtual plan and that pedicle screws were accurately inserted without signs of breach.
CONCLUSION
The use of 3D technology has greatly facilitated the performance of the occipitothoracic fixation and could, in the future, contribute to safer pediatric spinal fixation procedures.
Topics: Cervical Vertebrae; Child; Humans; Male; Occipital Bone; Pedicle Screws; Spinal Fusion; Surgery, Computer-Assisted
PubMed: 33728473
DOI: 10.1093/ons/opab060