What occurs during flexion of the sphenobasilar synchondrosis (SBS)?

• A. The greater wings of the sphenoid and lateral angles of the occiput move inferiorly and separate
• B. The greater wings of the sphenoid and occiput move superiorly and approximate
• C. The sphenoid and occiput rotate around the foramen magnum
• D. The occiput moves anteriorly while sphenoid moves posteriorly

Answer: (A)

Flexion of the sphenobasilar synchondrosis is the phase where the two bones move apart at the base of the skull, producing a widening of the cranial base. In this pattern, the greater wings of the sphenoid move downward (inferiorly) and the lateral angles of the occiput also move downward. This coordinated downward movement of both bones creates separation at the SBS, which is what defines flexion. Think of the cranial bones tipping and translating to increase the distance between the sphenoid and occiput, aligning with the inhalation-like expansion described in cranial rhythm. The other patterns would imply inward approximation or rotation around the foramen magnum, which correspond to extension or other non-flexion motions, not the flexion pattern.