Ligament of Berry is formed by
The posterior layer of the thyroid capsule is thick. On either side it forms a suspensory ligament for the thyroid gland known as ligament of Berry .The ligaments are attached chiefly to the cricoid cartilage, and may extend to the thyroid cartilage. They support the thyroid gland, and do not let it sink into the mediastinum.
Investing layer of Deep Cervical fascia
Pretracheal layer
Prevertebral layer
Pharyngobasilar fascia