Which ligament provides a connection to the superior sternum and resists downward movement?

The interclavicular ligament serves as a crucial connection between the superior sternum and the two clavicles. Its primary function is to provide stability to the sternoclavicular joint while resisting excessive downward movement of the clavicles. This ligament acts as a supportive structure during arm movements that may place stress on the shoulder girdle, ensuring that the clavicles remain properly positioned in relation to the sternum.

In the context of the other options:

• The costoclavicular ligament primarily stabilizes the clavicle in relation to the first rib.

• The anterior sternoclavicular ligament is responsible for reinforcing the front of the sternoclavicular joint and preventing excessive movement but does not specifically resist downward movement.

• The posterior sternoclavicular ligament serves a similar role to the anterior ligament but focuses on providing support at the back.

Thus, the interclavicular ligament's specific role in connecting to the superior sternum and preventing downward displacement makes it the correct answer.