Neck

The neck is the part of the body connecting the head to the torso (shoulders and trunk). It is a narrow passage through which pass the airway, the esophagus, the major blood vessels carrying blood to the head, and nerves branching from the spinal cord.

The neck affords the head considerable mobility: forward and backward bending, lateral flexion, and rotation. This is possible because the muscles and bones of the neck share the burden of supporting the weight and movements of the head.

Bone structure

The core of the neck consists of the cervical vertebrae (vertebrae), the upper section of the spinal column. Humans and most other mammals have seven cervical vertebrae. The two uppermost vertebrae have specialized functions: the first supports the head, while the second permits rotation. Within the vertebral column runs the spinal cord, which is the conduit for signals from the brain.

Muscles and movement

Various muscles surround the neck. Those on the sides allow the head to flex and rotate, while those at the back keep the head upright. Other muscles contribute to swallowing and speech. When the neck is held in poor posture for prolonged periods—for example, while seated at a computer—the muscles become fatigued and cause pain.

Passages and structures

The neck contains the esophagus (food passage) and the trachea (airway), which is attached to the larynx (voice box). Major blood vessels—both those supplying blood to the head and those returning it—run on both sides. The thyroid gland, an endocrine gland situated just below the larynx, and lymph nodes, which participate in immune defense, are also located there.

Health and injury

Because many vital passages are concentrated in the neck, neck injury can be serious. Motor vehicle collisions can cause muscle and ligament injuries (whiplash), while fracture of the cervical vertebrae can damage the spinal cord and result in paralysis. Common neck pain typically results from poor posture or muscle strain and usually improves with rest and time.