Your neck contains a surprisingly dense collection of vital structures packed into a relatively small space. Seven vertebrae, dozens of muscles, major blood vessels, critical nerves, glands that regulate your metabolism, airways, food passages, and chains of immune tissue all run through or sit within the neck. Here’s a closer look at each system and what it does.
Seven Vertebrae That Support Your Head
The bony framework of your neck is the cervical spine, a stack of seven vertebrae labeled C1 through C7. Together they support the weight of your head, which averages 10 to 13 pounds, while still allowing a wide range of motion: tilting forward and backward, rotating side to side, and bending ear to shoulder.
The top two vertebrae are specialized. C1, called the atlas, is a ring-shaped bone that sits right at the base of your skull and holds your head upright. C2, called the axis, has a peg-like projection that lets the atlas pivot against it, giving you that side-to-side “no” rotation. The remaining five vertebrae (C3 through C7) are connected by small facet joints in the back that guide the neck’s bending and twisting movements. Running through the center of all seven bones is a hollow canal that surrounds and protects the spinal cord. Small openings in C1 through C6 also create a protected pathway for the vertebral arteries, which carry blood up to your brain.
The Throat: Airway and Food Passage
Two tubes run vertically through your neck, one for air and one for food, stacked front to back. The trachea (windpipe) sits in front. It’s held open by rings of cartilage so it doesn’t collapse when you breathe, and its inner lining traps dust and germs in a layer of mucus that tiny hair-like structures push upward to be swallowed or coughed out. Directly behind the trachea is the esophagus, the muscular tube that carries food from your throat down to your stomach.
Sitting above both tubes is the pharynx, a shared space at the back of your throat where air and food temporarily use the same passageway. Just below the pharynx, between the fourth and sixth vertebrae, is the larynx, or voice box. The larynx has two jobs. During breathing, it stays open to let air pass into the trachea. During swallowing, a flap called the epiglottis folds down over it like a trap door to keep food out of your airway. The larynx is also where your vocal cords sit. When you speak, air from the lungs passes between the cords, making them vibrate to produce sound. Male vocal cords are longer (15 to 23 mm) than female vocal cords (13 to 17 mm), and the cartilage framework of the larynx meets at a sharper angle in men (90 degrees versus 120 degrees in women), which is why the “Adam’s apple” is more prominent in males.
Major Blood Vessels
Your neck is a highway for blood traveling between your heart and brain. On each side, a carotid artery carries oxygen-rich blood upward to your head and brain. Running alongside these arteries are three pairs of jugular veins that return used blood back toward the heart. The internal jugular veins are the largest, draining blood from the brain. The external jugular veins collect blood from areas outside the skull, and the smaller anterior jugular veins run along the front of the neck on either side of the windpipe. All of these veins eventually feed into the subclavian veins beneath your collarbones.
Glands That Control Your Metabolism
The thyroid gland wraps around the front of your trachea, just below the voice box, with one lobe on each side. In a healthy adult it weighs roughly 10 to 20 grams (about the size of two small plums) and is one of the most blood-vessel-rich organs in your body. It produces hormones that regulate how fast your cells use energy, affecting everything from heart rate to body temperature. The thyroid also releases a hormone involved in keeping calcium levels in your blood from getting too high.
Embedded in the back surface of the thyroid are four tiny parathyroid glands, each about the size of a grain of rice. They secrete a hormone that does the opposite job: raising blood calcium when it drops too low. Together, these glands maintain the tight calcium balance your muscles and nerves need to function.
Muscles That Move and Stabilize
More than 20 muscles crisscross the neck, organized into three groups: front (anterior), side (lateral), and back (posterior). They work together to move your head, stabilize your spine, and assist with breathing, swallowing, and speaking.
- Front muscles include the scalene muscles, which lift your first two ribs during each breath, and two groups of smaller muscles above and below the hyoid bone that move your voice box and the floor of your mouth when you swallow or talk.
- Side muscles control head movements from the base of the skull and let you twist and tilt your head.
- Back muscles include superficial strap-like muscles for extending and rotating your head, deep suboccipital muscles just below the base of your skull, and a group of muscles that help you move your head forward and backward while stabilizing your spine.
The Hyoid Bone
Just below your jawline sits a small, horseshoe-shaped bone called the hyoid. It’s the only bone in your entire body that doesn’t directly connect to another bone. Instead, it floats in place, anchored by muscles, ligaments, and cartilage. The hyoid serves as an attachment point for the tongue, the floor of the mouth, the epiglottis, and the voice box. Without it, speaking, swallowing, and breathing would all be significantly harder.
Nerves Running Through the Neck
The spinal cord itself passes through the cervical vertebrae, but several important individual nerves also travel through the neck. The most notable is the vagus nerve, the longest cranial nerve in the body. It exits the skull and descends through the neck between the carotid artery and jugular vein on each side, then continues all the way down to the large intestine. Along the way it sends branches to the throat, voice box, heart, lungs, esophagus, and digestive tract. Your two vagus nerves carry about 75% of the nerve fibers responsible for “rest and digest” functions, regulating heart rate, digestion, and breathing without any conscious effort on your part.
Other nerves passing through the neck include the phrenic nerve, which controls the diaphragm (and therefore your ability to breathe), and the nerves branching off the cervical spinal cord that serve your arms, shoulders, and upper back.
Lymph Nodes and Immune Tissue
Your neck contains roughly 300 lymph nodes organized into chains that run from just below the chin all the way down to the collarbones. Clinicians map them into six levels. Level I nodes sit under the chin and along the jawline. Levels II, III, and IV form a chain running down each side of the neck alongside the jugular vein, from the skull base to the collarbone. Level V nodes fill the back triangle of the neck between the large side muscle and the trapezius. Level VI nodes cluster in the front of the neck around the trachea and voice box.
These nodes filter fluid draining from your head, face, mouth, and throat, trapping bacteria, viruses, and abnormal cells. When you feel swollen “glands” during a cold or sore throat, you’re feeling lymph nodes that have ramped up their immune response. Because so many nodes are concentrated here, the neck is often the first place you notice signs of infection or, less commonly, other conditions that affect the lymphatic system.