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Platybasia; Specialty: Neurosurgical, orthopedic: Symptoms: Platybasia is characterised by abnormal flattening of the skull base as defined as a base of skull angle over 143º.In the absence of neural compression, pain at the back of the skull and upper part of the neck is the most common symptom.
Basilar invagination is invagination (infolding) of the base of the skull that occurs when the top of the C2 vertebra migrates upward. It can cause narrowing of the foramen magnum (the opening in the skull where the spinal cord passes through to the brain). It also may press on the lower brainstem. [1]
Potentially life-threatening complications, all of which become more common in more severe OI, include: tearing of the major arteries, such as the aorta; [1]: 333 [11] pulmonary valve insufficiency secondary to distortion of the ribcage; [1]: 335–341 [12] and basilar invagination. [13]: 106–107
Other features are: parietal bossing, basilar invagination (atlantoaxial impaction), persistent metopic suture, abnormal ear structures with hearing loss, supernumerary ribs, hemivertebrae with spondylosis, small and high scapulae, hypoplasia of illiac bones, absence of the pubic bone, short / absent fibular bones, short / absent radial bones ...
Several indirect measurements on CT can be used to assess ligamentous integrity at the craniocervical junction. The Wackenheim line, a straight line extending along the posterior margin of the clivus through the dens, should not intersect the dens on plain film, with violation of this relationship raising concern for basilar invagination.
In tunicates, invagination is the first mechanism that takes place during gastrulation. The four largest endoderm cells induce the invagination process in the tunicates. Invagination consists of the internal movements of a sheet of cells (the endoderm) based on changes in their shape.
The sphenethmoid bone forms as three bones: the lesser wings and the anterior part of the base. These two parts of the sphenethmoid may be distinguished as orbitosphenoids and presphenoid, respectively, although there is often some degree of fusion. Only the parasphenoid appears to be entirely absent in mammals.
The cytostome is located on the anterior end of the cell close to a structure known as the flagellar pocket. The flagellar pocket is also an invagination in the cell and also serves as a site of endocytosis. The opening of the cytostome is approximately level with the opening of the flagellar pocket. [3] Ciliophora is a phylum of protozoa. The ...