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BIO - 168 Final Exam Study Guide

Terms in this set (120)

Most cranial fontanelles and sutures normally close by the time a child is 2-3 years old, and mature sutures begin to appear by about age 12. The coronal, sagittal and lambdoid sutures may take up to 40 years to fully close. In birth defects called craniosynostosis, these sutures close prematurely. This presents a problem in that the brain is still growing and expanding. Craniosynostosis results in an abnormally shaped head (plagiocephaly), although its consequences can be much more serious.The implications and severity of craniosynostosis depend on how many sutures are involved; simple craniosynostosis involves only one suture, and complex craniosynostosis involves more than one suture. In some children a suture on one side is affected, and in other children both are. The sagittal suture is most commonly affected, followed by the coronal suture, and then the metopic suture. The metopic suture extends from the anterior fontanelle to the nose. Synostosis, or bone fusion, of the lambdoid suture is rare. Craniosynostosis, usually affecting multiple sutures, may also occur in association with syndromes. A syndrome is a condition that is characterized by a common set of clinical symptoms.Imagine holding a balloon as it is being inflated. Your hands prevent that part of the balloon beneath them from expanding, but the unrestrained parts of the balloon will continue to expand. Predict the deformities given the information provided. Image A, above, represents the direction of skull expansion following premature fusion of the sagittal suture. Images B and C show images of skull deformities as a result of craniosynostosis. Ear locations are shown in Figure C.Besides cranial deformities, trapping a growing brain within a rigid cranium affects the alignment of the orbits, causing misalignment of the eyes (strabismus), and in complex craniosynostosis, pressure within the cranial cavity can lead to headache, seizures, loss of vision and hearing, and, of course, brain damage. Surgical correction is implemented at the earliest age possible to prevent the continuing progression of damage during growth.After reading the text above, with its content and terminology, predict the following clinically observable outcomes of early suture fusion: