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Embryology of the Spinal Cord, Peripheral Nerves, and Vertebrae
Published in Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand, Pediatric Regional Anesthesia, 2019
Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand
At this stage, the meninges develop from the paraxial mesoderm, and three fundamental zones may be identified within the neural tube (Figure 1.10): The ependymal zone, next to the central canalThe mantle zone, outside the ependymal zone, in which neuroblasts and neuroglia can be identifiedThe marginal zone, formed mainly by growing nerve fibers (cells are scarce)
Mitochondrial Dysfunction and Hearing Loss
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
The ear starts its developmental during the 3 weeks after the fertilization; then during the 23 days period the otic placode is evident. As in any organ, the development of the ear has specific temporal and spatial changes, with many genes involved. At this time, there is a trilaminar embryo (ectoderm, mesoderm and endoderm). In the median ectoderm, the subjacent cells constitute the prechordal plate and notochordal plate. In the prechordal plate, the stomodeum forms. The mesoderm located lateral to the midline (paraxial mesoderm) is segmented in somitomeres. There are seven somitomeres from prosencephalon to the level of the otic placode. When the anterior neural tube closes, the otic placode and neural epithelium are separated for thin ectodermic, then the placode epithelium thickens.6 It is important to point out, that all the skeleton and connective tissue of the face are from neural crest origin.7
The skeleton and muscles
Published in Frank J. Dye, Human Life Before Birth, 2019
Paraxial mesoderm becomes segmented into paired aggregates of tissue called somites (see Figure 14.3B). The first somites to appear (early in the embryonic period) are in the head region. Subsequently, additional pairs of somites form in a progressively caudal direction. Each somite is organized into two regions: sclerotome and dermatomyotome (see Figure 14.3C). Cells of the sclerotome leave the somites and aggregate around the notochord (the primitive axial skeleton of the embryo) and developing spinal cord. These cells give rise to the vertebrae (by the process of endochondral ossification) and to the intervertebral discs (masses of fibrocartilage between vertebrae). Despite the importance of the notochord to the developing embryo, the notochord's only contribution to the adult is the nucleus pulposus, which occupies the core of each disc. Ossification (bone formation) replaces the original cartilaginous vertebral column with a bony one. This process begins during the embryonic period and continues into about the 25th year of life.
Brachial distal biceps injuries
Published in The Physician and Sportsmedicine, 2019
Drew Krumm, Peter Lasater, Guillaume Dumont, Travis J. Menge
Many growth factors, regulatory mechanisms, and genes contribute to the health of skeletal muscle. These all play a role in myogenesis and skeletal muscle differentiation. Skeletal muscle originates from somites arising from the paraxial mesoderm. Mesodermal stem cells are the earliest elements of myogenesis [7]. Exercise and aging have structural and metabolic changes on skeletal muscle. During endurance exercise, IL-6 is released which inhibits TNF-alpha, consequently reducing muscle fiber apoptosis. Resistance exercise, or anaerobic training, induces skeletal muscle hypertrophy (increase in the size of muscle fibers) and activation of satellite cells, which increases the number of muscle fibers. During exercise, reactive oxygen species can be formed, leading to cellular alterations and possible injury. Furthermore, aging can lead to sarcopenia, or the loss of skeletal muscle mass and function. This decrease is muscle strength is due to an increase in catabolism and decrease in anabolism [8]. Both aging and certain exercises have lasting effects on skeletal muscle that may predispose some individuals to distal biceps injuries.
Familial predisposition of thoracic outlet syndrome: does a familial syndrome exist? Report of cases and review of literature
Published in Acta Chirurgica Belgica, 2021
Jens Goeteyn, Niels Pesser, Bart van Nuenen, Marc van Sambeek, Joep Teijink
The presence of CRs and its influence on TOS has been researched thoroughly. There have been several case reports about CRs in multiple members of the same family. The skeletal system arises from the paraxial mesoderm [9]. The Hox genes are a family of transcription factors that regulate the embryogenesis of the body axis [10,11]. These genes regulate patterning of the axial skeleton in vertebrates and Hox gene mutants often display abnormalities of the vertebral column, including CRs [12]. The co-occurrence of rudimentary or even absent 12th ribs in 23.6% of cases with CR indicates that a homeotic shift occurred during embryogenesis [9].
Posterior Fossa Decompression and superficial durotomy rather than complete durotomy and duraplasty in the management of Chiari 1
Published in Neurological Research, 2021
Adem Aslan, Usame Rakip, Mehmet Gazi Boyacı, Serhat Yildizhan, Serhat Kormaz, Emre Atay, Necmettin Coban
Aydin et al. [28] concluded that the underdevelopment of occipital somites arising from paraxial mesoderm during intrauterine development is the main cause of CMs. It has been reported that normal sized posterior fossa herniation is induced secondary to overcrowding in the posterior fossa, and displacement of anatomical structures in the posterior fossa probably contributes to CM symptoms. It was concluded that the formation of syringomyelia was directly caused by the obstruction in the foramen magnum.