The ligament of berry

The last 2 cm of the extralaryngeal course of the recurrent laryngeal nerve is an area of critical anatomical importance. It is the site of greatest risk for neuropraxia, the site of development of the artificial genu and point of maximal tension within the recurrent laryngeal nerve at thyroidectomy and the site of bifurcation of the recurrent laryngeal nerve. In this last 2 cm segment, the Ligament of Berry which attaches the thyroid to the trachea is located. Two fascial layers are described in the region of the Ligament of Berry, covering the last 2 cm of the extralaryngeal course of the recurrent nerve. The more superficial layer, the superficial vascular fascial layer, contains branches of the inferior thyroid artery, the superior parathyroid gland, and the Tubercle of Zuckerkandl. Following dissection and division of this layer, the recurrent laryngeal nerve will be seen to lie on the deeper layer, the more fibrous and denser true Ligament of Berry. At thyroidectomy, once the fibrous Ligament of Berry layer is divided, the recurrent laryngeal nerve relaxes and adopts a serpiginous course in the tracheoesophageal groove. The Ligament of Berry maybe in two layers with thyroid tissue between the two layers. Because of anteromedial rotation of the thyroid and larynx and trachea, the recurrent laryngeal nerve lies lateral to the Ligament of Berry and deep to the superficial vascular fascial layer. The recurrent laryngeal nerve thus lies between the two layers but does not pass through the Ligament of Berry.