What structure divides the nasal cavity in the center of the nose?

The vomer is a thin, flat bone that forms part of the nasal septum, which is the structure that divides the nasal cavity into two halves. Its position is crucial for maintaining the integrity of the nasal structure as it separates the left and right nostrils. The vomer articulates with several other bones in the skull, including the sphenoid and the maxilla, contributing to the overall shape and function of the nasal cavity.

In comparison, the palatine bones are involved in forming the hard palate of the mouth and do not play a direct role in dividing the nasal cavity. The sternum is a flat bone located in the center of the chest and does not relate to the nasal cavity at all. The epicranius is a muscle that covers the upper part of the skull and is not a structural component of the nasal anatomy. Thus, the vomer is specifically responsible for partitioning the nasal cavity, making it the correct answer.