Craniosynostosis
Nonsyndromic craniosynostosis occurs much more frequently than syndromic. The most common premature closure occurs in the sagittal suture, which leads to scaphocephaly, dolichocephaly, or elongated head. The next most common…
Spinal Dysraphism (Continued)
A far more devastating variant of spina bifida aperta is myelomeningocele, in which the spinal cord or nerve roots, or both, protrude through the posterior bony and cutaneous defects due…
Spinal Dysraphism
Cutaneous stigmata of spina bifida occulta include dimples, dermal sinuses, subcutaneous lipomas, tufts of hair, or hemangiomas. Cutaneous lesions may occur in isolation, or herald an underlying tethered cord due…
Fetal Brain Growth in the First Trimester
At 49 days of age (see top, Plate 1-9), the brain and spinal cord undergo further bending that situates both appropriately in the developing head and trunk. The cephalic flexure…
Defective Neural Tube Formation (Continued)
Several other clinical conditions characterized by congenital failure of fusion of the midline structures of the spinal column are grouped under the general classification of spinal dysraphism. These various manifestations…
Central Nervous System at 36 Days
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Defective Neural Tube Formation
An encephalocele is a protrusion of a portion of the brain or meninges through a skull defect. Although an encephalocele usually occurs in the occipital region in patients from Europe…
Embryo at 20 to 24 Days
By embryonic day 21, the neural tube in the midsection of the embryo has closed; the neural folds fuse and the underlying neuroectoderm encloses a fluid-filled cavity that becomes the…
Central Nervous System at 28 Days
The region of the neural tube posterior to the midbrain undergoes a dramatic series of morphogenetic changes that transform it into the rhombencephalon. The most noticeable event is the establishment…
Embryo at 18 Days
At this point, the fate of ectodermal cells, particularly that of the visibly thickened sheet of cells above the notochord called the neural plate, can be mapped fairly precisely. Stem…
