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Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
In humans, the vertebral column normally consists of 33 vertebrae divided into five subdivisions (Figure 11.1), based on some distinguishing characteristics of the vertebrae in each subdivision. The five subdivisions are, rostrally to caudally: Cervical, or neck, region comprising 7 vertebrae, denoted as C1 to C7. The C1 vertebra supports the skull, and the C2 vertebra serves as a pivot for C1.Thoracic, or chest, region comprising 12 vertebrae, denoted as T1 to T12. These vertebrae support the 12 pairs of ribs, which are joined ventrally at the sternum, or breastbone.Lumbar, or lower back, region comprising 5 vertebrae, denoted as L1 to L5.Sacral, or thigh, region comprising 5 fused vertebrae (the sacrum) having a roughly triangular shape. The sacrum articulates laterally with the hip bones. The vertebrae in this region are denoted as S1 to S5.Coccyx, or tailbone, region comprising 4 fused, rudimentary vertebrae.
Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
The pelvis is a rigid massive bony basin connecting the trunk and the lower extremities. The pelvis is made up of three different and distinctive bones: The upper portion made up of two bones named ilium, the middle part which is somehow a lower part is the pubis, and the bottom portion is the ischium. The two ilium bones are united by the sacrum bone and the pubis bone is united by pubic symphysis. The total unification (fusion) of these bones occurs at the time of puberty. At the lower extremity of the sacrum is a tiny bone named coccyx or tailbone.
Designing for Lower Torso and Leg Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The sacrum (refer to Section 4.4.1 description, Figure 4.8 illustration) with five vertebral elements fused into a shield-shaped bone, functions as a supportive base for the vertebrae above it. The lateral edges of the sacrum also serve as pivot points to allow subtle movements between the sacrum and the iliac portion (ilium) of the bony pelvis. These movements are necessary for walking and running. The coccyx or tailbone—three to five very small, variably fused vertebrae caudal to the sacrum—taper to a point above the rectum and anus.
Validating a wheelchair in-seat activity tracker
Published in Assistive Technology, 2022
Nauman Ahad, Sharon E. Sonenblum, Mark A. Davenport, Stephen Sprigle
Wheelchair users, especially users with spinal cord injuries, experience limited sensory cues to move within their chairs. This leads to extended periods of stationary sitting (Sonenblum et al., 2016) which causes extensive loading of body tissues, particularly around the ischial tuberosities and sacrum and coccyx. Increased loading of tissues, both in magnitude and duration, can hinder blood and oxygen supply to tissues which can cause pressure ulcers. About 46% of 300,000 people with spinal cord injuries in the United States experience pressure ulcers (N.S.C.I.S.C, 2015). After sustaining spinal cord injuries, more than 20% require costly surgeries to manage these ulcers (Saunders et al., 2012). The recurrence rate for pressure ulcers can be up to 79% which further adds to healthcare costs (Bates-Jensen et al., 2009). These pressure ulcers can become infected, leading to life-threatening complications such as sepsis – such complications are associated with mortality rates of 48%.(N.S.C.I.S.C, 2015).
Biomechanics of adjacent segment after three-level lumbar fusion, hybrid single-level semi-rigid fixation with two-level lumbar fusion
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Mingzheng Zhang, Weiyan Ren, Zhongjun Mo, Jian Li, Fang Pu, Yubo Fan
The elements of the sacrum and coccyx below S1 were fixed in all directions. To validate the intact model, loading conditions were replicated from an in vitro study (Yamamoto et al. 1989). A pre-load of 150 N and a 10 Nm moment were applied to the top surface of L1. For the implanted models, displacement- controlled FE analysis was used and loads were applied in two steps (Zhong et al. 2009). First, a pre-load of 150 N was applied to the top surface of L1. Then a moment was applied in increments of 0.3 Nm, up to a maximum of 30 Nm. All results of the sub-steps were saved and the result having the same range of motion (ROM) as the intact model was selected for analysis. The two-step load procedure was replicated from a previous study (Zhong et al. 2009), which was in accordance with the hybrid testing protocol (Panjabi 2007; Ruberté et al. 2009).
Analysis of sagittal profile of spine using 3D ultrasound imaging: a phantom study and preliminary subject test
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2020
Timothy Tin-Yan Lee, James Chung-Wai Cheung, Siu-Yu Law, Michael Kai Tsun To, Jason Pui Yin Cheung, Yong-Ping Zheng
Human spine composes of five regions: cervical, thoracic, lumbar, sacrum and coccyx. Thoracic kyphosis and lumbar lordosis are two common sagittal parameters when analyzing sagittal profile. For normal individuals, acceptable ranges for kyphosis and lordosis are between 20–50 degrees and 31–79 degrees, respectively (Bridwell and Bernhardt 1989; Boseker et al. 2000). It is essential to maintain a balanced sagittal spinal profile because an optimal degree of kyphosis and lordosis is necessary to maintain spine motor control with minimum energy expenditure, enhance the load tolerance of the spine and increase spinal muscle efficiency (Kim et al. 2006). From a clinical point of view, a better understanding of the sagittal spinal profile helps to evaluate patients with spinal pathology, assist surgical planning and minimise complications such as spinal deformity issues like sagittal imbalance (Cho et al. 2014).