Joint guide
Your spine is a stack of 33 vertebrae in the usual count, cushioned by 23 discs, with four gentle curves. Each region moves differently: the neck turns the most, the upper back twists, and the lower back bends forward and back. Discs and joints change with age in almost everyone, usually without causing pain.
It is built to bend, lift and twist. Rounding your back while lifting hasn't been shown to cause back pain, and exercise lowers the chance of a new episode. What discs need is less certain: people who run or walk briskly tend to have healthier-looking discs, but those studies can't show cause and effect.
This guide covers how the spine is built and how far each region moves, what discs need, the evidence on bending, lifting and cracking, and the moves that keep every region moving and strong. If your back or neck hurts, start with our pain guides.
7 in the neck, 12 in the upper back, 5 in the lower back, 5 fused into the sacrum and about 4 fused into the tailbone, with 23 discs between them. Variations are common: about a quarter of young adults in one X-ray study had a transitional vertebra where the lower back meets the sacrum.
From the side, the neck and lower back curve inward and the upper back and sacrum curve outward. Normal values vary a lot, and people with back pain have the same lower-back curve, on average, as people without.
The neck turns about 75 to 80 degrees each way. The upper back is the twisting region. The lower back bends forward and back but twists only 1 to 2 degrees per level.
Disc degeneration shows on scans of 37% of 20-year-olds without back pain, rising to 96% at 80. A scan report doesn't explain pain on its own.
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Rounding your lower back while lifting hasn't been linked with back pain, and lifting-technique training didn't prevent it. Exercise combined with education cut the chance of a new episode of low back pain by about 45% in trials.
In finger joints filmed with MRI (magnetic resonance imaging), the crack came from a gas bubble forming in the joint fluid. Pain relief after manipulation is the same with or without a pop, and forcing your own neck to crack has caused rare but serious harm.
In the usual count there are 33 vertebrae, and the 24 above the sacrum move separately.
Thirty-three is the textbook count, not a rule. In one X-ray study of young adults without symptoms, 26.4% had a transitional vertebra where the lower back meets the sacrum, a variant StatPearls puts at 35% of the general population. In a CT (computed tomography) study, 3.4% of people had 11 pairs of ribs rather than 12.
There are 23 discs: 6 in the neck, 12 in the upper back and 5 in the lower back. There's none between the skull and the first vertebra, or between the first two. Each has a gel centre (the nucleus pulposus), 66% to 86% water, inside 15 to 25 layers of tough fibres (the annulus) that alternate in direction, like a radial tyre. Together the discs make up about a quarter to a third of the spine's length.
Behind each pair of vertebrae sit two small facet joints, with cartilage and joint fluid like any other synovial joint. They guide and limit movement, and their angle is why the upper back twists and the lower back doesn't. At the base, the two sacroiliac (SI) joints link the sacrum to the pelvis. They move only 2 to 4 mm and are held by some of the strongest ligaments in the body.
Long ligaments run down the front and back of the vertebral bodies, and shorter ones link the arches and bony points behind them. At the top, strong ligaments hold the first two vertebrae together. The spinal cord runs through the canal and usually ends at the first or second lumbar vertebra, below which the nerve roots continue down; 31 pairs of spinal nerves leave between the vertebrae.
From the side, the neck and lower back curve inward (lordosis) and the upper back and sacrum curve outward (kyphosis). The outward curves are there at birth; the neck curve forms as babies hold up their heads, and the lower-back curve as they stand. On standing X-rays of 300 adults, the lower-back curve averaged 60 degrees, give or take 10.
An upper-back curve of more than 40 degrees is often called hyperkyphosis, and the curve grows with age. StatPearls notes that in a review of 7,633 healthy adults the curve was above 40 degrees in 65%, so a fixed cut-off over-labels older people. Our posture guides cover it in detail.
The erector spinae and multifidus straighten the spine and control each level; the quadratus lumborum bends it sideways; the abdominal muscles bend and twist the trunk; the psoas joins the lower spine to the thigh; and the sternocleidomastoid and scalenes turn and tilt the neck. Each guide covers one muscle.
Range depends on how it's measured (X-ray, motion capture or a hand-held angle gauge), on whether you move yourself or are moved, and on your position, so figures from different studies don't line up exactly. Treat them as typical, not as targets.
With motion capture, young adults turned the head about 75 to 80 degrees each way, nodded through about 130 degrees from chest to ceiling, and tilted ear towards shoulder about 38 to 45 degrees each way. Most nodding happens where the skull meets the top vertebra, and most turning between the top two vertebrae.
On X-rays of 1,230 people without symptoms, the lower neck's range from bending forward to bending back fell from 68 degrees in people in their 20s to 45 in their 70s.
The upper back is the spine's twisting region: about 25 degrees each way from top to bottom in a CT study of maximal trunk rotation, most of it in the middle and lower segments. The ribs and the angle of the facet joints limit bending.
On X-rays of 627 adults, the lower back bent about 31 to 35 degrees forward and 19 to 20 degrees back, about 52 degrees in all, with more in women. It twists very little: 1 to 2 degrees per level during a 45-degree turn of the trunk.
Side bending has been measured in only one small, preliminary X-ray study (82 people). Range there fell steadily from the 40s, to about half the young-adult figure in the 70s and about a third in the 80s, with most movement in the middle of the lower back and least at the lowest level.
In 60 adults, 15 everyday tasks needed a median of about 20 degrees of neck bending and 18 degrees of turning, a small part of the full range. Reversing a car was the exception: it used 92% of full turning range.
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Across 16 studies, bending forward, bending back and side bending in the lower back fell with age, particularly from 40 to 50 and after 60, while twisting changed very little. In both the neck and the lower back, bending back falls more than bending forward. The decline isn't steady, and women are generally more mobile.
In 21 prevention trials (30,850 people), exercise combined with education cut the risk of a new episode of low back pain by about 45%, with moderate-quality evidence; exercise alone may help too, with lower-quality evidence. Education alone, back belts and shoe insoles didn't prevent it.
In 701 adults who had just recovered from back pain, a 6-month walking and education programme with six physiotherapy sessions nearly doubled the time before the next episode that limited activity (208 days against 112 with no treatment). The walkers did report more leg and foot complaints.
Across 33 studies of 3,110 people without back pain, disc degeneration showed on scans of 37% of 20-year-olds and 96% of 80-year-olds, and disc bulges in 30% and 84%. Findings like these are often part of normal ageing.
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People with low back pain have the same lower-back curve on average as people without (8 studies), and an umbrella review of 41 reviews found no consensus that posture or physical exposures cause back pain. People with back pain do tend to move their lower back less and more slowly, but it isn't known whether that comes before or after the pain.
The UK consensus on exercise for osteoporosis recommends resistance and impact exercise, strength and balance training, and spinal extension exercise, and advises avoiding postures with a lot of spinal rounding in exercise and daily life. After a spinal fracture, impact should usually go no higher than brisk walking.
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In a trial of 101 postmenopausal women with low bone mass, 8 months of twice-weekly, closely supervised heavy lifting and impact training raised lower-spine bone density by 2.9%, while it fell 1.2% with gentle home exercise. There was one minor back spasm. The women were screened and supervised, so this isn't a reason to lift heavy alone with osteoporosis.
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The disc is the body's largest structure without a blood supply. Oxygen and glucose seep in (diffuse) from tiny blood vessels in the bone above and below and around the outer rim, so the centre of the disc gets the least. In a healthy disc, nerves reach only the outer two-thirds of the tough outer ring, not the centre.
Under the day's load, disc height falls by 10% to 20%, and it recovers overnight when you lie down. That's why you're about 1.5 to 2 cm shorter by the evening.
Loading squeezes water out of discs, and it soaks back in when you rest, so movement does change the disc's water. But small nutrients such as oxygen and glucose arrive almost entirely by diffusion, and this fluid flow has virtually no direct effect on them, though it may help larger molecules. The popular idea that movement pumps food into your discs is only partly true.
In 79 adults aged 25 to 35, regular joggers (20 to 40 km a week) had about 9% better disc hydration on MRI than inactive people, and movement at the pace of brisk walking or slow jogging went with the healthiest discs. A 2026 meta-analysis of 39 studies (4,152 people) linked upright loading, mostly running, with better disc health.
But these studies compare groups at one point in time, the certainty is very low, and they can't show that running caused the difference. Discs also shrink briefly straight after a run, as water is squeezed out.
In the one 6-month trial, 40 adults with chronic back pain did progressive upright aerobic and strength exercise, and their discs didn't change compared with the control group. A 12-week run-walk trial found more favourable disc changes in some subgroups, which its authors call a hypothesis to test, not a result.
A review of mostly animal and lab studies concluded that repeated upright loading at slow to moderate speeds, like walking and jogging, is likely good for discs, while long static loads, twisting under heavy load, high-impact or explosive loading and inactivity are likely bad. It's a reasonable guide, not proof in people.
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Discs are fullest of water after a night lying down. If bending forward flares your back, our editorial precaution, not a tested rule, is to leave heavy or repeated loaded bending until later in the day, as our segmental roll-down page also advises.
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In 9 of 11 studies, there was no difference in how much people with and without back pain bent their lower back when lifting; where there was a difference, people with back pain bent less, not more. The one study that followed people over time found no link with back pain starting or lasting. The evidence is low quality.
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In 7 trials of 19,317 workers, training and advice on how to lift, with or without lifting aids, didn't prevent back pain.
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In 8 studies that followed workers, the odds of back pain rose by about 11% for every extra 10 kg lifted and about 9% for every extra 10 lifts a day. Reviews that applied stricter tests of cause and effect found the evidence conflicting, and an umbrella review found no consensus that lifting causes back pain.
A 2026 review of 10 mostly lab-based studies found that round-back lifting put more shearing force on the lowest lumbar joint, and called the direction the spine moves a risk factor worth changing. Another 2026 review, of deadlifting, argued that trained lifters often round a little without clear evidence of more injury, and that sudden jumps in training load were the more consistent risk. Neither settles it.
Bending and lifting are normal jobs for a healthy spine. Lift in whatever way feels strong and controlled, keep the load close, and build weight and volume gradually. Treat very heavy, very frequent or sudden loading with more respect, and with osteoporosis avoid deep, loaded rounding.
When a finger joint was filmed cracking with real-time MRI, the sound came with a gas-filled cavity suddenly forming in the joint fluid as the surfaces separated, not with a bone going back into place. The spine's small joints are assumed to work the same way, but that comes from finger-joint imaging.
During manipulation, the pops don't come from one targeted joint: a lower-back thrust gave about 5 pops on average, as often on the opposite side as the target side, and 92% of upper-neck manipulations gave pops on both sides.
In 5 studies, pain after manipulation was no better when there was a pop, and in 70 people with low back pain, outcomes were the same with or without one. Even so, in a survey of 478 adults, many believed the pop meant realignment and was needed for success.
We found no study that has followed people who crack their own mid or lower back, so there's no evidence of harm or of benefit. For the neck, a 2026 review found 24 published cases of harm after people manipulated their own necks: 9 severe and 4 catastrophic, including 2 deaths, almost all within 2 days. The authors found no evidence that such harm is common, with very low certainty.
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Across 47 trials (9,211 people), spinal manipulation for chronic low back pain worked about as well as other recommended treatments, and its side effects were mostly mild and short-lived.
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In a study of 818 strokes, the link between chiropractic visits and stroke was no stronger than for GP visits, most likely because people with an early tear in a neck artery seek care for neck pain and headache.
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The NHS says chiropractic or osteopathy may not be safe if you take blood thinners or have a raised risk of stroke, have very weak or damaged bones or joints, or have a nerve condition such as peripheral neuropathy. Practitioners in the UK must be registered with the General Chiropractic Council or the General Osteopathic Council.
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Painless cracking that happens as you move needs no treatment. You don't need to force it: if you feel the urge many times a day, move your back through its range and strengthen it instead. Don't force your neck, and don't self-manipulate with osteoporosis or after an injury.
Our editorial starting point: a 10 to 15 minute routine that takes your neck, upper back and lower back through bending, arching, side bending and twisting, on most days. Lower-back range falls from about 40, and exercise is what prevented back pain in trials, though no trial has tested a routine like this one on its own.
Our editorial starting point: 2 or 3 days a week of back-extension, trunk and hip work, building the load gradually. Our back pain plan's doses are a good guide: 2 to 3 sets of 6 to 8 bird dogs each side, holding each for 3 to 5 seconds, and 3 sets of 8 to 10 kettlebell deadlifts, light to start. With osteoporosis, include back-extension exercises such as the low cobra, as the UK consensus recommends.
Walking built up gradually over months delayed the next episode of back pain in the WalkBack trial, and brisk walking and slow jogging went with the healthiest-looking discs. Build up steadily, as the walkers there reported more leg and foot complaints.
Start light, keep the load close and add weight in small steps. In the deadlifting review, sudden jumps in training load were a more consistent risk than the shape of the back, and technique training alone didn't prevent back pain.
Move slowly, within comfort, and skip any move that sends pain, pins and needles or numbness down an arm or leg. Starting doses from each move's page and our workouts: 8 slow chin tucks, 6 thoracic rotations each side, 8 slow cat-cow waves and 2 to 4 holds of 20 to 30 seconds for the knee hug.
3D demoChin tuckBeginner · No equipment
3D demoNeck CARsBeginner · No equipment
3D demoSide neck stretchBeginner · No equipment
3D demoThoracic rotationBeginner · No equipment
3D demoSide-lying Open Book RotationBeginner · No equipment
3D demoFoam Roller Thoracic ExtensionBeginner · A foam roller
3D demoOverhead side bendBeginner · No equipment
3D demoCat-cowBeginner · No equipment
3D demoSphinx pose (Salamba Bhujangasana)Beginner · No equipment
3D demoProne press-up (McKenzie press-up)Beginner · No equipment
3D demoDouble knee-to-chest stretchBeginner · No equipment
3D demoSupine spinal twist (Supta Matsyendrasana)Beginner · No equipment
3D demoSegmental Roll DownIntermediate · No equipment
3D demoHip-hinge practiceBeginner · No equipment2 or 3 days a week, building the load gradually (our editorial starting point; each move's page has its dose). With osteoporosis, favour the extension moves, skip deep rounding, and keep the curl-up small.
3D demoLying chin tuckBeginner · No equipment
3D demoChin tuck with head liftIntermediate · No equipment
3D demoIsometric neck holds (four-way)Beginner · No equipment
3D demoProne Y-T-W raisesBeginner · No equipment
3D demoSeated upper-back lift (sit tall, shoulders back)Beginner · A bench or box
3D demoLow cobra (Bhujangasana)Beginner · No equipment
3D demoLocust pose (Salabhasana)Beginner · No equipment
3D demoBird dogBeginner · No equipment
3D demoBird dog, one limb at a timeBeginner · No equipment
3D demoDead bugBeginner · No equipment
3D demoKnee side plankBeginner · No equipment
3D demoSide plankIntermediate · No equipment
3D demoMcGill curl-upBeginner · No equipment
3D demoGlute bridgeBeginner · No equipment
3D demoHalf-kneeling Pallof pressBeginner · A band + An anchor point
3D demoKettlebell deadliftBeginner · A kettlebell
3D demoDumbbell Romanian deadliftIntermediate · A dumbbell
3D demoBack extension on a 45-degree benchIntermediate · A bench or box
3D demoSuitcase carryIntermediate · A dumbbell + A kettlebellThe spine mobility routine takes every region through every direction in 15 minutes. The others focus on one region, or on strength and bone.
A 15-minute routine that moves your neck, upper back and lower back through bending, arching, side bending and twisting, then holds the spine steady.
15 minBeginner12 movesNo equipmentSeven gentle stretches and mobility moves for a stiff lower back, done lying and kneeling.
12 minBeginner7 movesA wallA 12-minute routine for a stiff upper back and rounded shoulders: chin tucks, wall angels, Y-T-W raises and open books.
12 minBeginner8 movesA foam roller, A wallEight gentle neck and shoulder stretches for desk stiffness, done standing or seated in ten minutes.
10 minBeginner8 movesA wallA 12-minute routine to move every joint through its range under control: slow neck, shoulder, hip and ankle circles, spine and hip rotation, and deep squats.
12 minBeginner10 movesA wallA 30-minute routine for a rounded upper back in later life, built from the SHEAF trial: floor back-strengthening, posture practice and gentle mobility.
30 minBeginner13 movesA bench or box, A wallA gentle 15-minute Pilates-based routine for ongoing low back pain, built from neutral-spine moves with options for backs that dislike bending or arching.
15 minBeginner10 movesNo equipmentA gentle 20-minute yoga sequence for back pain, based on the first weeks of a 12-week trial programme: lying, all-fours and standing poses, then rest.
20 minBeginner12 movesNo equipmentA 15-minute beginner core workout on the floor: dead bugs, bird dogs, knee planks, side planks and curl-ups.
15 minBeginner6 movesNo equipmentImpact, strength and balance for stronger bones, following UK osteoporosis consensus advice, with options for every level.
40 minBeginner14 movesA kettlebell, Other / check instructionsA one-line orientation for each; the guides below have the detail, a staged plan and the warning signs.
Usually not a sign of serious damage. Our back pain guide sorts it by where it hurts and what eases it, and our long-term back pain guide covers pain that lasts.
A herniated (slipped) disc, sciatica and spinal stenosis can all send pain down a leg. Disc bulges are common on scans of people without pain, and leg pain from stenosis typically eases when you sit or bend forward.
Neck pain, a stiff neck and tech neck usually settle with movement. Arm pain, tingling or numbness can come from a pinched nerve, and whiplash, headaches from the neck and neck arthritis each have their own guide.
Sacroiliac joint pain is felt low and to one side of the back; upper back pain sits between the shoulder blades, and some causes there need a doctor.
Osteoporosis changes how you exercise the spine. Ankylosing spondylitis is an inflammatory back pain that usually starts before 45 and responds to daily mobility and strength work.
Kyphosis, swayback, scoliosis and forward head posture: our posture guides cover what's normal variation and what exercise can and can't change.
If you have back pain and pain, tingling, weakness or numbness in both legs; a loss of feeling around your genitals or anus; changes in your bladder or bowels, such as difficulty peeing, or peeing or pooing yourself; changes in how your penis or vagina feels during sex, or not being able to get or keep an erection or to orgasm; chest pain; or if it started after a serious accident, such as a car accident. Do not drive yourself to A&E.
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If you have back pain and feel hot, cold, shivery or generally unwell, or it's severe pain that starts suddenly or is getting worse quickly. In the US, contact your doctor or urgent care.
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If it doesn't improve after treating it at home for a few weeks or stops you doing day-to-day activities; you've lost weight without trying to; there's a lump or swelling in your back, or your back has changed shape; it doesn't improve after resting or is worse at night; it's worse when sneezing, coughing or pooing; or it's coming from the top of your back, between your shoulders, rather than your lower back.
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If you feel clumsiness in your hands, or numbness, pins and needles or weakness that is getting worse in one or both arms; you've had problems with your balance or walking since your neck pain started; or your neck pain comes with a severe headache. Phone 111 if your practice is closed.
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If you have neck pain and feel generally unwell, if it started when you were ill with other problems such as rheumatoid arthritis or cancer, or if it comes with blurred vision, ringing in your ears or dizziness. The NHS also advises seeing a GP for pins and needles or a cold arm.
Stop or shrink any move that sends pain, pins and needles or numbness down an arm or leg. Dizziness or changes in your vision during neck movements are a stop sign. With osteoporosis or a past spinal fracture, avoid deep, loaded rounding.
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It's the usual count. A transitional vertebra at the base of the spine shows up in about a quarter to a third of people, and a few have 11 pairs of ribs rather than 12.
From the side it has four natural curves, and normal values vary widely.
People with back pain have the same lower-back curve on average as people without, and reviews found no consensus that posture causes back pain. Our posture guides cover it.
Rounding while lifting hasn't been shown to cause back pain, and technique training didn't prevent it. Build loads gradually instead.
These findings are common in people without pain and rise with age: degeneration shows in 96% of 80-year-olds without back pain.
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Only partly. Loading moves water in and out of discs, but oxygen and glucose arrive almost entirely by diffusion.
In finger joints filmed with MRI, the sound was gas forming in joint fluid. During manipulation, pops come from either side of the spine, and they don't predict who gets better.
A "slipped disc" is a herniation: some of the gel centre pushes out through the outer fibres. The whole disc doesn't move.
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Supervised, progressive heavy training raised spine bone density in a trial, and the UK consensus recommends resistance and impact exercise, with care to avoid deep spinal rounding.
Usually 33: 7 in the neck, 12 in the upper back, 5 in the lower back, 5 fused into the sacrum and about 4 fused into the tailbone. The 24 above the sacrum move separately. Variations are common: about a quarter of people have a transitional vertebra where the lower back meets the sacrum.
23: 6 in the neck, 12 in the upper back and 5 in the lower back. There's no disc between the skull and the first vertebra, or between the first two. Together the discs make up about a quarter to a third of the spine's length.
Occasional, painless cracking as you move has no known harm, though no study has followed people who do it habitually. The sound is a gas bubble forming in joint fluid, not a bone slipping back into place, and pain improves just as much after manipulation with or without a pop. Don't force your neck, and don't self-manipulate with osteoporosis or after an injury.
Twisting can pull the surfaces of the small facet joints apart. In finger joints filmed with MRI, a quick separation like this formed a gas bubble with a pop, and the spine is thought to work the same way. If it doesn't hurt, it doesn't need treatment.
Moving your neck gently every day is good; forcing it to crack is not recommended. A 2026 review found 24 published cases of harm after people manipulated their own necks, some serious, though there's no evidence that such harm is common. New or unusual neck pain or headache needs checking, not cracking.
Studies haven't found that people who round their lower back more when lifting are more likely to get back pain, and lifting-technique training didn't prevent back pain in 19,317 workers. Very heavy or very frequent lifting at work is linked with a little more back pain, so build up gradually. With osteoporosis, avoid deep rounding under load.
Not when the load is built up gradually. In a supervised trial, heavy lifting raised spine bone density in women with low bone mass, and our back pain plans bring deadlifts back on purpose. Sudden jumps in training load look like a more consistent risk than the shape of your back.
No. The lower back is built to bend, about 31 to 35 degrees forward on X-ray, and reviews found no consensus that bending causes back pain. If bending flares current pain, favour the direction that eases it for now, and with osteoporosis avoid deep rounding.
Probably regular, varied movement and moderate upright loading, like walking and jogging. Discs have no blood supply, so nutrients seep in from the bone above and below. Runners and brisk walkers tend to have healthier-looking discs, but those studies compare groups at one point in time, at very low certainty, and the one 6-month exercise trial found no change in the discs.
Yes. On scans of people with no back pain, disc degeneration shows in 37% at 20 and 96% at 80, and bulges in 30% and 84%. These findings often have nothing to do with pain.
Young adults turn about 75 to 80 degrees each way and nod through about 130 degrees from chest to ceiling, and range falls gradually with age. Everyday tasks use only a small part of it, but reversing a car uses nearly all of your turning.
From the side, the neck and lower back curve inward (lordosis) and the upper back and sacrum curve outward (kyphosis). Babies have the outward curves at birth; the neck curve forms as they hold up their heads and the lower-back curve as they stand. Normal values vary widely, and people with back pain have the same lower-back curve on average as people without.
Education about how your joints work, not a diagnosis, and clinical review of these guides is pending. For a painful, swollen or injured joint, see the pain guide for that area and a doctor or physiotherapist, and stop any exercise that causes sharp or increasing pain. Health disclaimer.
