The structure indicated is the coracoclavicular ligament

The coracoclavicular ligament is one of the ligaments which stabilises the acromioclavicular joint. The acromioclavicular joint is formed between the acromion of the scapula and the clavicle. It is a small synovial joint that is stabilised by the following ligaments:

• Acromioclavicular ligament (consists of superior and inferior parts)
• Coracoclavicular ligaments

The coracoclavicular ligaments consist of two parts:

• Trapezoid ligament
• Conoid ligament

The coracoclavicular ligament, as the name suggests connects the clavicle to the coracoid process of the scapula.

Learn more about the anatomy of the shoulder joint in this tutorial.