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Anatomy of the Pelvis
Published in Gowri Dorairajan, Management of Normal and High Risk Labour During Childbirth, 2022
Therefore, ligaments provide the sole stabilising mechanism for the sacroiliac articulation. The transfer of weight from axial skeleton to ilia occurs primarily through the interosseous sacroiliac ligaments and thence to the femora on standing and ischial tuberosities on sitting. The weight of the body conveyed through the fifth lumbar vertebra has a tendency to thrust the sacrum downwards and forwards towards the symphysis. The interosseous sacroiliac and iliolumbar ligaments oppose these gliding movements of the joint surfaces. Similarly, the function of opposing the forward rotation of sacral promontory is performed by sacro-tuberous and sacrospinous ligaments. The sacrospinous ligaments slacken in later months of gestation, allowing minimal rotation of the sacrum.
Pelvis
Published in Harold Ellis, Adrian Kendal Dixon, Bari M. Logan, David J. Bowden, Human Sectional Anatomy, 2017
Harold Ellis, Adrian Kendal Dixon, Bari M. Logan, David J. Bowden
The transverse processes of the fifth lumbar vertebra (12) are bulky and all but reach the sacrum, particularly (in this subject) on the left side. Reference to Axial section 3 shows partial sacralization of L5, a very common variation.
The Spinal Cord and the Suboccipital Triangle
Published in Gene L. Colborn, David B. Lause, Musculoskeletal Anatomy, 2009
Gene L. Colborn, David B. Lause
Upon a sacrum identify the articular processes for the fifth lumbar vertebra. Note the spinous processes and the sacral hiatus. Observe the forwardly concave shape (a primary curve) of the sacrum which, with the coccyx, forms the posterior bony wall of the pelvis. Note the sacral cornua. The ventral portion of the body of the first sacral vertebra projects into the pelvis as the promontory of the sacrum. In some people the first sacral vertebra is partially or wholly separate from the remaining part of the sacrum, a condition known as lumbarization of S1.
Deep vein thrombosis of the common iliac vein caused by neurogenic heterotopic ossification in the anterior lower lumbar spine of a patient with complete paraplegia due to radiation-induced myelopathy
Published in The Journal of Spinal Cord Medicine, 2022
Du Hwan Kim, Mathieu Boudier-Revéret, Duk Hyun Sung, Min Cheol Chang
The left and right CIA and CIV branch from the abdominal aorta and inferior vena cava, respectively, at the level of the fourth or fifth lumbar vertebra.11 MTS is a condition in which the right CIA overlies and compresses the left CIV.11 However, whether venous compression in MTS can cause DVT remains uncertain. In this case, we speculated that the left CIV was vulnerable to DVT due to pulsation of the right CIA opposite the NHO anterior to the lower lumbar spine (L3–L5). As the NHO in our patient had matured and enlarged, the left CIV became compressed between the right CIA and the NHO. This mechanical compression of the left CIV is thought to have resulted in DVT development. SCI above the sixth thoracic segment reduces descending autonomic control over the sympathetic portion of the spinal cord. The elimination of descending autonomic projections to the spinal sympathetic pre-ganglionic neurons can decrease the tone of the CIA,12 which might have contributed to the development of DVT. Whether the decreased tone of deep veins is associated with the development of DVT in patients with SCI has not been studied to date. Also, the hypermobility of the spine due to the fusion of L4 to S1 might have caused mechanical stress to the vessels, which might have contributed to the development of DVT in the CIV. Further research should explore this issue.
Lumbopelvic Fixation Versus Novel Adjustable Plate for Sacral Fractures: A Retrospective Comparative Study
Published in Journal of Investigative Surgery, 2020
Ruipeng Zhang, Yingchao Yin, Shilun Li, Ao Li, Zhiyong Hou, Yingze Zhang
For the patients in group A, a posterior middle incision was conducted from the L3 (third lumbar vertebra) or L4 (fourth lumbar vertebra) to the S3 (third sacral vertebra) or S4 (fourth sacral vertebra) segment according to the level of the fracture line. Subcutaneous soft tissues were separated to the level of the lumbodorsal fascia. Longitudinal spilt of the lumbodorsal fascia was conducted along the connection of the facet joints. Surgical exposure was conducted along the gap of spinalis and longissimus in the superficial muscle layers. Then, the ipsilateral posterior superior iliac spine parapophysis and facet joint of L4 and L5 (fifth lumbar vertebra) could be exposed directly through the gap of multifidus and longissimus in the deep layer of muscles. The Universal Spinal System (USS, Synthes, Switzerland) was employed to accomplish lumbar polyaxial pedicle screw placement in L4 and L5 vertebra. The highest point of ipsilateral PSIS was then perforated with an awl. Pedicle probes were predrilled to create a channel from the perforated point to the anterior cortex (Figure 1A). A greater than 5- to 7-cm deep probe should be forbidden to lower the rate of iatrogenic injury. Then, polyaxial pedicle screws of suitable length were inserted to the preformed channels. A precurved longitudinal rod was placed into the pedicle polyaxial screws. The nuts were tightened after the sacral fractures were reduced under the supervision of the C-arm (Figure 1B). Layered wound closure was performed after drain insertion.
Influence of energy absorbers on Malgaigne fracture mechanism in lumbar-pelvic system under vertical impact load
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
K. Arkusz, T. Klekiel, G. Sławiński, R. Będziński
The results of numerical analysis of shearing force on the pelvic girdle under vertical impact load (7 m/s) are consistent with the analysis of medical cases indicating the Malgaigne fracture as the most common in traffic road collision and IED explosion (Alvarez 2011; Gokalp et al. 2016). Due to the lack of experimental data, the ultimate compressive strength of each bone of LPC was assumed as 150 MPa (Masson et al. 2010; Havaldar et al. 2014). Displacements caused by the rigid seat induced the uniform stress distribution in the pelvic girdle (Figure 3D). Slightly higher values of von Mises stresses localised in the right ilium were the result of pelvic asymmetry indicating its lower slope compared to the left ilium (Boulay et al. 2006). Further analysis pointed the maximum stress (104 MPa) in the right ischial tuberosity in the first 2 ms after impact. These are, however, no destructive forces. At 4.5 ms, the maximum von Mises stress (149 MPa) were localised in fifth lumbar vertebra, causing the first fracture in LPC. The main role in stress transfer played by the anterior sacroiliac ligaments (both right and left), which had an elongation exceeded 7% (at 4.31 and 5 ms, respectively) indicating the micro-damaging of this ligament (Wheaton and Jensen 2011). Tear in this ligaments caused the concentration of von Mises stress in the ilium, transferred by the sacrospinous and sacrotuberous ligaments, resulting in the wing of the ilium fracture (180 MPa at 8 ms). This injury resulted in the tear of the posterior sacroiliac ligaments (Table 5), breaking in continuity of the pelvic ring and another fracture of the ischium and the pubis (Figure 2), together leading to the Malgaigne fracture. Obtained results indicated a key moment – lumbar vertebra fracture due to its contact with the ilium bone, as a cause of stress concentration in the pelvic girdle.