Anatomy of the Neck: Bones, Discs, Joints and Nerves

Your neck (cervical spine) is built from seven bones called vertebrae, stacked from the base of your skull to the top of your upper back. Between most of them sits a disc that absorbs load. At the back, small paired joints called facet joints guide movement. The spinal cord runs down a canal through the middle, and eight pairs of nerves branch off to supply the neck, shoulder, arm and hand. Muscles in layers hold the head up and move it.

Each of these parts can be a source of pain, and each tends to produce a slightly different pattern. Knowing which part does what helps explain why neck problems so often reach the shoulder blade, the top of the shoulder and the arm.

Key takeaways

Seven vertebrae, eight nerve pairs: the neck has seven cervical vertebrae and eight pairs of cervical spinal nerves.
The top two bones are special: the first (atlas) and second (axis) vertebrae have no disc between them and allow about half of the neck’s turning movement.
Discs and facet joints share the load: discs sit at the front between vertebrae, and facet joints sit in pairs at the back.
The lower neck works hardest: the levels between the fifth, sixth and seventh vertebrae are where disc and nerve root problems most often occur.
Neck structures often refer pain: the lower neck commonly sends pain to the shoulder blade and top of the shoulder, and the upper neck to the head.

The bones: seven cervical vertebrae

The neck vertebrae are numbered C1 to C7 from the top. They are the smallest vertebrae in the spine, which lets the neck move more than any other part of the spine.

C1 (atlas): a ring of bone with no body. The skull rests on it. Most nodding “yes” happens between the skull and C1.
C2 (axis): has a peg of bone (the dens) that points up through the ring of C1. C1 turns around this peg, giving roughly half of your ability to turn your head “no”.
C3 to C7: similar in shape, each with a body at the front, an arch at the back, and small side holes for the vertebral arteries. C7 has a longer spine at the back that you can usually feel as the bump at the base of the neck.

Seen from the side, the neck has a gentle forward curve (cervical lordosis). The amount of curve varies a lot between healthy people. A straighter neck on an X-ray is common and is not, on its own, a cause of pain.

The discs

An intervertebral disc sits between the bodies of each pair of vertebrae from C2 down to the first thoracic vertebra. There is no disc between the skull and C1, or between C1 and C2. Each disc has a tough outer ring of fibers (the annulus fibrosus) around a softer, gel-like center (the nucleus pulposus).

With age, discs lose water and height. This is part of normal aging and shows on scans of many people without neck pain, often from the age of 40 onward. When a disc bulges or part of its center pushes through the outer ring (a disc herniation), it can press on or irritate a nearby nerve root.

The joints

Facet joints (zygapophyseal joints): small paired joints at the back of each level, lined with cartilage and surrounded by a capsule. They guide bending, extending and turning. Irritated facet joints usually cause pain to one side of the neck that is worse looking up or turning toward that side.
Uncovertebral joints: small ridges at the sides of the vertebral bodies from C3 to C7. With age they can thicken and narrow the openings where nerves leave the spine.
Upper neck joints: the joints between the skull, C1 and C2. Irritation here is a common source of headache felt at the back of the head (cervicogenic headache).

Ligaments run the length of the spine and between the vertebrae, limiting movement at the extremes. Whiplash injuries can strain these ligaments along with the facet joint capsules and muscles.

The spinal cord and nerve roots

The spinal cord runs down the spinal canal, protected by the ring of bone formed by each vertebra. At each level a nerve root leaves through a small opening on each side (the intervertebral foramen). In the neck, the nerve roots C1 to C7 exit above the vertebra of the same number. The C8 root exits between C7 and the first thoracic vertebra. That is why the neck has eight nerve pairs but only seven vertebrae.

C1 to C4: supply the back of the head, the neck and the top of the shoulder. C3 to C5 also form the phrenic nerve, which drives the diaphragm.
C5 to C8, with T1: form the brachial plexus, which supplies the shoulder, arm and hand.

A nerve root can be squeezed when a disc bulges into the opening or when bony changes narrow it. This is called cervical radiculopathy. It typically causes arm pain that follows a strip of skin, with possible tingling, numbness or weakness in that nerve’s area. C7 is the root most often affected, followed by C6.

If the spinal canal narrows enough to press on the cord itself, the result is cervical myelopathy. This tends to cause clumsy hands, numb fingers and unsteady walking rather than sharp neck pain. It is less common than radiculopathy and needs medical assessment.

A neck that is small enough to turn easily is also small enough to feel every hour you spend looking down.

The muscles

Deep neck flexors (longus colli and longus capitis): run down the front of the spine and help hold the neck curve steady. They often test weak in people with long-standing neck pain.
Suboccipital muscles: small muscles between the skull and the top two vertebrae that fine-tune head position.
Back of the neck (splenius, semispinalis): extend and turn the head and hold it up when you look down.
Side and front (sternocleidomastoid, scalenes): turn and tilt the head. The scalenes attach to the upper ribs, and the arm’s nerves pass between them.
Neck to shoulder blade (upper trapezius, levator scapulae): link the neck to the shoulder blade, so shoulder blade position and neck load affect each other.

How the neck moves

Most people can turn the head roughly 70 to 90 degrees to each side, and this range tends to reduce with age. About half of that turning comes from the joint between C1 and C2. Nodding comes mostly from the joint between the skull and C1. Bending forward and back, and tilting ear to shoulder, come mostly from C2 to C7. The lower neck levels, C5 to C7, take the most bending load, which is part of why wear changes and disc problems are most common there.

How the neck connects to the shoulder and upper back

The neck does not work alone. The lowest neck vertebra joins the upper back (thoracic spine), and a stiff upper back makes the lower neck bend more to look up or down. Muscles from the neck attach to the shoulder blade, so carrying, reaching and shrugging all load the neck. The nerves to the shoulder and arm leave the neck, so a problem at a neck level can be felt at the shoulder blade, the top of the shoulder, or down the arm.

Which problems start where

Muscles and soft tissue: neck strain and the stiff neck you wake up with. Usually one-sided and achy, and often settles within days to a few weeks.
Facet joints: one-sided neck pain, worse looking up or turning, that may refer to the shoulder blade.
Discs: neck pain, sometimes with arm pain if a nerve root is involved. Arm pain from a disc often takes 6 to 12 weeks or longer to settle.
Nerve roots: arm pain, tingling or weakness in a strip of the arm (radiculopathy).
Upper neck: headache from the back of the head toward the forehead, and sometimes a type of dizziness linked to neck movement.
Spinal cord: myelopathy, with hand clumsiness and balance change.

What it means for you: a scan that shows disc wear or narrowing does not, on its own, explain your pain, because these changes are common in people without pain. The pattern of your symptoms, and how they change with movement, usually tells a physical therapist or doctor more than the picture alone.

Get it checked if

Arm weakness is getting worse: see a doctor today.
Your hands or walking change: clumsy hands, trouble with buttons, numbness in both hands, unsteady walking, or a change in bladder or bowel control needs urgent medical assessment.
Neck pain follows a fall, collision or car accident: go to the emergency department.
Fever comes with a stiff neck: especially with headache, a rash or sensitivity to light, call your local emergency number.
Sudden severe headache or neck pain: particularly with dizziness, double vision, slurred speech or trouble swallowing, call your local emergency number.