The longus colli muscle is a long, slender muscle located in the neck. It consists of three parts: the anterior, middle, and posterior. The anterior and middle parts originate at the transverse processes of the cervical vertebrae (bones in the neck), and the posterior part originates at the spinous processes of the thoracic vertebrae (bones in the chest). The three parts converge at the base of the skull and insert into the anterior arch of the atlas (first cervical vertebra).

The longus colli muscle has several important functions in the head and neck. It helps to flex the neck and head, and also helps to stabilize the cervical spine. It is also involved in respiration, as it helps to elevate the rib cage during inspiration.

The longus colli muscle is innervated by the cervical spinal nerves. It is a voluntary muscle, meaning that it can be controlled voluntarily by the person.

In some cases, the longus colli muscle may be surgically modified or altered to address certain medical conditions, such as problems with neck movement or instability of the cervical spine. It may also be used as a donor muscle for reconstructive surgery in the head and neck region.