The middle point on the anterior margin of the foramen magnum, opposite the opisthion. [G. basis, a base]
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ba·si·on 'bā-sē-.än, -zē- n the midpoint of the anterior margin of the foramen magnum
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n.
the midpoint of the anterior border of the large hole (foramen magnum) at the base of the skull.
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ba·si·on (baґse-on) [Gr. basis base] [TA] a craniometric landmark located at the midpoint of the anterior border of the foramen magnum, at the base of the clivus. Called also point Ba. basial, basialis adj
Basion, in an inferior view of the skull.
Medical dictionary. 2011.