0000000000068657
AUTHOR
Shahed Nalla
showing 14 related works from this author
Sexual dimorphism in the vertebral wedging of the human lumbar vertebrae and its importance as a comparative framework for understanding the wedging …
2020
Lumbar lordosis is a key element of the upright posture, being interpreted as a consequence of bipedal locomotion. There is consensus that the generic modern human pattern of metameric vertebral body wedging is sexually dimorphic in modern humans. However, recently published studies have compared this pattern with other hominins, such as Neanderthals. These tried to establish whether the (male) Neanderthal lumbar vertebrae express a pattern that falls within or outside the range of modern human males. In the present study, data collected by 3D landmarks of the lumbar vertebrae of modern humans from different geographic regions and Neanderthals (Ntotal = 505 individual vertebrae) are used to…
Three-dimensional geometric morphometrics of thorax-pelvis covariation and its potential for predicting the thorax morphology: A case study on Kebara…
2020
The skeletal torso is a complex structure of outstanding importance in understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as researchers apply their own anatomical expertise to the process. Among different fossil reconstruction methods, 3D geometric morphometric techniques have been increasingly used in the last decades. Two-block partial least squares analysis has shown great potential for predicting missing elements by exploiting the covariation between two structures (blocks) in a reference sample: one block can be predicted from the other one based on the strength of covariation between blocks. The first aim of this study is to test w…
The Retrotransverse Foramen of the Atlas Is not a Modern Anatomic Variation
2019
Background The retrotransverse foramen (RTF) is a nonmetric variant of the atlas vertebra that consists of an abnormal accessory foramen located on the posterior root of the transverse process and it extends from the posterior root of the transverse process to the root of the posterior arch. Its presence has been related to regional variations of the venous circulation. It is currently unknown whether the RTF is a modern or an ancient anatomic variation. Case Description We analyzed the skeletal remains from the late-ancient Roman necropolis (II-VI centuries ad ) of La Boatella (Valencia, Spain) and we found a well-preserved individual skeleton that presented with a left retrotransverse for…
Prevalence of anatomic variations of the atlas vertebra
2018
Abstract BACKGROUND CONTEXT The retrotransverse foramen (RTF), arcuate foramen (AF), unclosed transverse foramen (UTF) and posterior atlas arch defects (PAAD) are anatomic variations of the atlas vertebra that surgeons must be aware of before spine surgery is performed. PURPOSE To analyze the prevalence of the AF, RTF, UTF, and PAAD. STUDY DESIGN Ex-vivo anatomical study. PATIENT SAMPLE Two hundred eighteen atlas vertebrae obtained from 100 Caucasian subjects and 118 sub-Saharan African subjects (48 Sotho subjects, 35 Xhosa subjects and 35 Zulu subjects). METHODS We studied 218 atlas vertebrae from skeletons of the Raymond A. Dart Collection in order to analyze the prevalence of AF, RTF, UT…
3D geometric morphometric analysis of variation in the human lumbar spine
2019
[Objectives]: The shape of the human lumbar spine is considered to be a consequence of erect posture. In addition, several other factors such as sexual dimorphism and variation in genetic backgrounds also influence lumbar vertebral morphology. Here we use 3D geometric morphometrics (GM) to analyze the 3D morphology of the lumbar spine in different human populations, exploring those potential causes of variation.
Atlases with Arcuate Foramen Present Cortical Bone Thickening That May Contribute to Lower Fracture Risk.
2018
To date, no information about the cortical bone microstructural properties in atlas vertebrae with arcuate foramen has been reported. As a result, we aimed to test in an experimental model if there is a cortical bone thickening in an atlas vertebra which has an arcuate foramen that may play a protective role against bone fracture.We analyzed by means of micro-computed tomography the cortical bone thickness, the cortical volume, and the medullary volume (SkyScan 1172 Bruker micro-CT NV, Kontich, Belgium) in cadaveric dry atlas vertebrae with arcuate foramen and without arcuate foramen. We also reviewed a case series of 31 posterior atlas arch fractures to correlate the possible presence in t…
The torso integration hypothesis revisited in Homo sapiens: Contributions to the understanding of hominin body shape evolution.
2018
Objectives: Lower thoracic widths and curvatures track upper pelvic widths and iliac blades curvatures in hominins and other primates (torso integration hypothesis). However, recent studies suggest that sexual dimorphism could challenge this assumption in Homo sapiens. We test the torso integration hypothesis in two modern human populations, both considering and excluding the effect of sexual dimorphism. We further assess covariation patterns between different thoracic and pelvic levels, and we explore the allometric effects on torso shape variation. Material and Methods: A sex-balanced sample of 50 anatomically connected torsos (25 Mediterraneans, 25 Sub-Saharan Africans) was segmented fro…
Possible Clinical Implications of Geographic Differences in Prevalence of Double Transverse Foramen
2019
The double transverse foramen (DBLTF) is a cervical spine anatomic variant. Current literature has presented prevalence values of DBLTF in Caucasian Mediterranean subjects that seem to be higher than those observed in other samples of subjects. Therefore we aimed to test if Caucasian Mediterranean subjects present a higher prevalence of the DBLTF than sub-Saharan African subjects.We analyzed the presence of DBLTF in cervical spines of 100 skeletons from Caucasian Mediterranean subjects and 91 skeletons from sub-Saharan African subjects, resulting in a total of 1337 cervical vertebrae having been studied.No DBLTF was found in vertebrae C1, C2, and C3. The pattern of prevalence observed in al…
Double Retrotransverse Foramen of Atlas (C1)
2018
Background The retrotransverse foramen is a nonmetric variant of C1 that consists of an abnormal accessory foramen on the posterior root of the transverse process. Case Description During a study on the prevalence of the retrotransverse foramen in 150 dry C1 vertebrae, we observed an exceptional C1 (0.67%) with a right double retrotransverse foramen of the 14 C1 vertebrae (9.3%). This has not been reported previously in the literature. No osteogenic reaction and no degenerative signs were observed in this C1 with the double retrotransverse foramen. Conclusions Neurosurgeons should be aware of the possible presence of the “conventional” retrotransverse foramen and the “exceptional” double re…
Can the transverse foramen/vertebral artery ratio of double transverse foramen subjects be a risk for vertebrobasilar transient ischemic attacks?
2018
The C6 is the cervical vertebra into which the vertebral artery enters the passage of the transverse foramen and it is the vertebra most affected by double transverse foramina. There is currently little information about the relation between the vertebral artery and the double transverse foramen in C6. We aimed to test whether subjects with a double transverse foramen in C6 have a reduced transverse foramen/vertebral artery ratio when compared with normal anatomy subjects who possess a single transverse foramen which may be a risk for transient vertebral artery stenosis. We measured the area of the transverse foramen and the vertebral artery in 27 double transverse and 56 normal anatomy sub…
Geometric Morphometric Studies in the Human Spine
2019
This chapter overviews the theoretical basics of geometric morphometrics (GM) and reviews its potential for the study of hominin vertebrae and vertebral columns. We show that challenges are related to seriality and the metameric nature of the spine. Measuring a series of vertebrae is a time-consuming process because the necessary sample sizes need to be multiplied by the number of vertebrae composing the spine or its anatomical parts. This is particularly true when measuring 3D semilandmarks of curves and surfaces in virtual anthropology. The lack of independence among vertebral series of a skeleton and the complex conceptual relation between the shape of vertebrae (parts) and the effect of…
The Decreasing Prevalence of the Arcuate Foramen
2018
[Background]: The arcuate foramen (AF), or ponticulus posticus, is an anatomic variant of the first cervical vertebra that consists of a complete or partial osseous bridge over the groove for the vertebral artery and extends from the posterior aspect of the superior articular facet to the superior lateral border of the posterior arch. The AF has been associated with clinical symptoms, such as headache, migraine, neck pain, shoulder pain, arm pain, and vertebral artery dissection. We aimed to test whether the prevalence of the AF has decreased in the modern human population over the past centuries as a result of reduction in inbreeding and endogamy.
Unexpected Persistent Dentocentral Synchondrosis of C2.
2017
Background The persistence of synchondrosis in adulthood can confound diagnostic decisions made during patient management. Case Description A 59-year-old woman who presented neck pain, acute headache, and acute cervical myelopathy symptoms after suffering whiplash grade 3 in a car rear-end impact underwent a conventional radiologic study that revealed no fracture and no anatomic spine variations. The magnetic resonance imaging study revealed no spinal cord intensity signal changes, but it showed a persistent (remnant) dentocentral synchondrosis that was undetected in a previous conventional radiographic evaluation. Conclusions The localization and level of the remnant of the dentocentral sy…
Assessing thoraco-pelvic covariation in Homo sapiens and Pan troglodytes: A 3D geometric morphometric approach
2019
[Objectives]: Understanding thoraco-pelvic integration in Homo sapiens and their closest living relatives (genus Pan) is of great importance within the context of human body shape evolution. However, studies assessing thoraco-pelvic covariation across Hominoidea species are scarce, although recent research would suggest shared covariation patterns in humans and chimpanzees but also species-specific features, with sexual dimorphism and allometry influencing thoraco-pelvic covariation in these taxa differently.