necks

Necks are the anatomical region that connects the head to the torso. In humans, the neck houses the cervical spine, seven vertebrae (C1–C7), intervertebral discs, and a complex set of muscles, fascia, and ligaments that support the head and permit its movement. The uppermost vertebrae form specialized joints: the atlas (C1) and axis (C2). The atlanto-occipital joint allows nodding, while the atlanto-axial joint enables most head rotation. The neck also contains major blood vessels, including the carotid arteries and internal jugular veins, and the nerves of the cervical plexus. The anterior neck contains endocrine and digestive structures such as the thyroid and parathyroid glands, as well as portions of the pharynx, larynx, and trachea. The posterior neck includes the spinal cord in its cervical region, cervical nerve roots, lymph nodes, and the paravertebral muscles.

Functions include supporting and stabilizing the head, protecting the upper spinal canal, and housing pathways for air, food, and the vascular and nerve supply to the head. Movement is produced by muscles such as the sternocleidomastoid and the scalene group, along with deeper neck muscles.

Common clinical concerns of the neck include muscle strains and stiffness, whiplash injuries after sudden impact, torticollis (abnormal neck positioning), cervical spondylosis, herniated discs, and nerve compression. Imaging and examination focus on alignment, disc integrity, vascular and neural status, and surrounding structures.

In nonhuman animals, neck length and musculature vary widely and can reflect ecological adaptations, such as elongated necks in certain herbivores.