Hemivertebrae cause an angling of the spine and are most commonly manifested in defects such as One probable cause of this failure is a lack of blood supply to the vertebrae. Hemivertebrae, or wedge-shaped vertebrae, are caused by failure of formation or segmentation of somites during This suite of malformations of the spine that occur during gestation is referred to as congenital vertebral defects. These defects can cause compression of the spinal cord due to deformation of the vertebral canal, spinal curvature, and alterations of the shape and number of vertebrae. If disrupted, the process of spinal formation can result in vertebral anomalies such as hemivertebrae, block vertebrae, butterfly vertebrae, transitional vertebrae, and in extreme cases, spina bifida. This allows the spinal nerves to pass between the precartilaginous vertebral bodies which later form the vertebral arches and protect the spinal nerves. There is then a sudden shift in which the cranial portion of each somite simultaneously recombines with the caudal portion of the directly anterior somite in a process known as resegmentation. Somites, the building blocks of the spine, are formed sequentially from anterior to posterior and then separate into cranial and caudal portions. The human spine usually consists of thirty-three vertebrae, seven of which are cervical (C1–C7), twelve are thoracic (T1–T12), five are lumbar (L1–L5), and nine are pelvic (five fused as the sacrum and four fused as the coccyx).Įmbryogenesis is an intricate and highly regulated process. These regions are classified by their differences in curvature. The vertebrae of the spine are organized into four regions (listed in order from cranial to caudal): cervical, thoracic, lumbar, and pelvic. Spinal column is the central structure in the vertebrate body from which stability, movement, and posture all derive.
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