Proximate cause, anatomical correlates, and obstetrical implication of a supernumerary lumbar vertebra in humans

Tague, Robert G.

doi:10.1002/ajpa.23361

Cited by 4 publications

(3 citation statements)

References 95 publications

(125 reference statements)

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“…In those specimens, the first coccygeal element is incorporated within the sacrum by complete fusion. In our sample, sacralizations of the coccyx were relatively common (32%) and frequently occurred in conjunction with lumbarizations, which is in accordance with previous findings (Derry, 1912 ; Mitchell, 1936 ; Tague, 2018 ). Therefore, attention must be paid not only to the first but also to the last sacral element, specifically the interarticular cornua, since such situations are otherwise not recognizable in isolated sacra.…”

Section: Discussionsupporting

confidence: 93%

“…Many authors suggested that obstetric disadvantages might result from segmentation anomalies (Breus & Kolisko, 1904;Buttenberg, 1962;Diehl & Holmberg, 1968;Kirchhoff, 1949;Kirchhoff, 1958;Mahato, 2018;Müller, 1932;Nastoulis et al, 2019;Tague, 2018;Winter, 1953). The pelvic inlet dimensions, for example, the conjugate, the inlet circumference, and the transverse diameter, may therefore vary with changes in the relative position of the promontory, sacral breadth, height, and sagittal curvature.…”

Section: Discussionmentioning

confidence: 99%

“…Homeotic border shifts have also been implicated in the evolution of the spinal segmentation formulae of mammals and particularly of hominins (e.g., Haeusler et al, 2002 , 2011 ; Machnicki & Reno, 2020 ; McCollum et al, 2010 ; Pilbeam, 2004 ; Williams et al, 2016 , 2019 ; Williams & Pilbeam, 2021 ). However, the precise mechanisms responsible for the number and morphological identities of the vertebrae are still elusive (Kudlicki, 2019 ; Tague, 2018 ), and it is unknown whether these Hox genes are responsible for segmentation anomalies since Hox gene mutations also involve severe perturbation of limb and pelvic morphology (Wellik & Capecchi, 2003 ).…”

Section: Introductionmentioning

confidence: 99%

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The morphological consequences of segmentation anomalies in the human sacrum

Krenn

Fornai

Webb

et al. 2021

American Journal of Biological Anthropology

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Objectives Despite the high frequency of segmentation anomalies in the human sacrum, their evolutionary and clinical implications remain controversial. Specifically, inconsistencies involving the classification and counting methods obscure accurate assessment of lumbosacral transitional vertebrae. Therefore, we aim to establish more reliable morphological and morphometric methods for differentiating between sacralizations and lumbarizations in clinical and paleontological contexts. Materials and Methods Using clinical CT data from 145 individuals aged 14–47 years, vertebral counts and the spatial relationship between the sacrum and adjoining bony structures were assessed, while the morphological variation of the sacrum was assessed using geometric morphometrics based on varied landmark configurations. Results The prevalence of lumbosacral and sacrococcygeal segmentation anomalies was 40%. Lumbarizations and sacralizations were reliably distinguishable based on the spatial relationship between the iliac crest and the upward or downward trajectory of the linea terminalis on the sacrum. Different craniocaudal orientations of the alae relative to the corpus of the first sacral vertebra were also reflected in the geometric morphometric analyses. The fusion of the coccyx (32%) was frequently coupled with lumbarizations, suggesting that the six‐element sacra more often incorporate the coccyx rather than the fifth lumbar vertebra. Conclusions Our approach allowed the consistent identification of segmentation anomalies even in isolated sacra. Additionally, our outcomes either suggest that homeotic border shifts often affect multiple spinal regions in a unidirectional way, or that sacrum length is highly conserved perhaps due to functional constraints. Our results elucidate the potential clinical, biomechanical, and evolutionary significance of lumbosacral transitional vertebrae.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The morphological consequences of segmentation anomalies in the human sacrum

Krenn

Fornai

Webb

et al. 2021

American Journal of Biological Anthropology

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References

2023

Asymptomatic Osseous Variations of the Postcranial Human Skeleton

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Lumbarization and sacralization: Domains of their co‐occurrence with other costal‐vertebral transformations are not identical

Tague

2024

American Journal of Biological Anthropology

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ObjectivesThis study evaluates whether sacralization of a lumbar vertebra and lumbarization of a sacral vertebra are a paired duality but with opposite expressions; the former is associated with 23 presacral vertebrae (PSV) and the latter with 25 PSV. Are sacralization and lumbarization local phenomena, involving only vertebra (V) 24 and V25, or are they associated with other costal‐vertebral transformations?Materials and MethodsStudy sample is of skeletonized humans, 431 females and 1405 males, who were 20–49 years of age‐at‐death and who died in the United States in the 20th and 21st centuries. Data collected are numbers of PSV and sacral vertebrae, presence of rib of V7, position of diaphragmatic vertebra, and transverse process and rib lengths of V5–V9, V18–V19, and V21–V22.ResultsFemales and males differ significantly in numbers of PSV. Both sexes show significant differences among individuals with 23 PSV, 24 PSV, and 25 PSV: (1) individuals with 23 PSV have the shortest ribs, whereas those with 25 PSV have the longest ribs, of V18 and V19; and (2) individuals with 23 PSV have the highest frequency of 6 sacral vertebrae, whereas those with 25 PSV have the highest frequency of 5 sacral vertebrae.DiscussionIndividuals with 23 PSV and 25 PSV show posterior and anterior homeotic transformation, respectively, of the thoracic‐lumbar and lumbar‐sacral boundaries, but only individuals with 25 PSV show transformation of the sacral–coccygeal boundary. As co‐occurring costal‐vertebral transformations differ between sacralization and lumbarization, inferentially the set of genes that influences these vertebrae also differs.

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Proximate cause, anatomical correlates, and obstetrical implication of a supernumerary lumbar vertebra in humans

Cited by 4 publications

References 95 publications

The morphological consequences of segmentation anomalies in the human sacrum

The morphological consequences of segmentation anomalies in the human sacrum

References

Lumbarization and sacralization: Domains of their co‐occurrence with other costal‐vertebral transformations are not identical

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