Properties and function of extensible ligaments in the necks of turkeys (Meleagris gallopavo) and other birds

Highly extensible ligaments connect the neural spines of successive vertebrae in the proximal part of the neck in birds. Their elastic properties, and their lengths in different neck positions, have been investigated in experiments on turkeys. Their properties are very similar to those of the ligamentum nuchae of artiodactyls. They are stretched to large strains when the head is lowered but do not develop sufficient force to support the extended head and neck without the aid of muscles.