Where does the longissimus muscle insert?

The longissimus muscle has several points of insertion that are crucial for its function in extending and laterally flexing the vertebral column. Specifically, it inserts on the ribs between the tubercles and the angles in both the thoracic and cervical regions. This attachment to the ribs allows the longissimus to play a significant role in stabilizing the thoracic spine during various movements, as well as contributing to the overall posture and balance of the body.

In addition to the rib insertions, the longissimus also attaches to the transverse processes of some cervical and lumbar vertebrae, and it can reach the mastoid process of the temporal bone; however, the most extensive and distinguishing feature involves its rib insertions, as these are particularly characteristic of the muscle's pathway. Thus, the option highlighting rib insertion captures the essence of what the longissimus primarily does in terms of its action and anatomical relevance.

The other choices are either overly specific or do not encapsulate the broader, more significant points of insertion and function, making the choice regarding the ribs the most comprehensive answer.