Corpus
Upper body

Hands & Wrists

Twenty-seven bones per hand, an opposable thumb, and a grip strength that predicts how long you'll live.

By The Corpus Atlas Editorial TeamUpdated Last reviewed How we source this

27

Bones per hand

Over a quarter, in both hands

Share of all body bones

Around 29

Joints per hand

An independent predictor of mortality

Grip strength

Overview

The hand is the most mechanically complex structure in the body outside the head. Twenty-seven bones, around thirty joints, and more than thirty muscles — most of them located in the forearm rather than the hand itself, connected by long tendons that run through the wrist like cables through a conduit. That arrangement keeps the fingers slim enough to be precise while retaining the power of large forearm muscles. The opposable thumb, which can rotate to touch each fingertip, is the feature that makes human tool use possible; it accounts for roughly 40% of hand function on its own. The hand is also disproportionately represented in the brain's sensory and motor maps, with a density of nerve endings in the fingertips that rivals anywhere in the body.

Interesting facts

  • There are no muscles in your fingers — the movements come from muscles in the forearm and palm pulling on long tendons.
  • Grip strength is one of the most reliable simple predictors of all-cause mortality, outperforming systolic blood pressure in some large cohort studies.
  • The fingertips contain thousands of touch receptors per square centimetre, enabling discrimination of surface features on the order of micrometres.
  • The hands and face occupy a disproportionately large share of the brain's sensory and motor cortex — the basis of the 'cortical homunculus' with its oversized hands.
  • Knuckle cracking is caused by gas bubble formation in the joint fluid, and long-term studies have found no association with arthritis.

Common misconceptions

  • Cracking your knuckles causes arthritis.
    Multiple studies, including one researcher's 60-year self-experiment on one hand, have found no association between knuckle cracking and osteoarthritis.
  • Carpal tunnel syndrome is caused by typing.
    The evidence linking ordinary keyboard use to carpal tunnel is weak. Forceful, repetitive gripping and vibration exposure are far stronger occupational risk factors, alongside diabetes, pregnancy and thyroid disease.
  • Hand arthritis means you should avoid using your hands.
    Hand exercise programmes improve grip strength and function in hand osteoarthritis; inactivity accelerates stiffness and weakness.
  • Wrist pain from a fall is only a sprain if you can still move it.
    Scaphoid fractures are frequently missed because movement is preserved and initial X-rays can appear normal — untreated, they risk permanent damage.

Anatomy & how it works

The hand and wrist combine a dense cluster of small bones with tendons controlled largely from the forearm.

  • Carpal bones

    Eight small bones forming the wrist, arranged in two rows and permitting complex multi-axis movement.

  • Metacarpals and phalanges

    The five palm bones and fourteen finger bones that give the hand its structure and reach.

  • Extrinsic tendons

    Long tendons from forearm muscles that flex and extend the fingers, passing through the wrist.

  • Intrinsic hand muscles

    Small muscles within the hand itself that control fine positioning, spread and thumb opposition.

  • Carpal tunnel

    A narrow passage at the wrist through which the median nerve and nine flexor tendons pass — the site of carpal tunnel syndrome.

  • Thumb carpometacarpal joint

    A saddle joint enabling thumb opposition; one of the most common sites of osteoarthritis in the body.

  • Ulnar and radial nerves

    Alongside the median nerve, these supply sensation and motor control across distinct territories of the hand.

Human grip divides broadly into power grips, where the object is held against the palm with the fingers wrapped around it, and precision grips, where it is held between fingertips and thumb. Power comes primarily from the forearm flexors pulling on long tendons; precision comes from the small
intrinsic musclesThe small muscles within the hand itself, responsible for fine positioning and control.
within the hand itself. The wrist's position governs both — flexor tendons lose mechanical efficiency when the wrist is bent, which is why grip is strongest with the wrist slightly extended, and why sustained flexed-wrist positions cause fatigue and pain.

Primary functions

  • Grasping and manipulating objects with both power and precision
  • Providing high-resolution touch and texture sensation
  • Opposing the thumb to the fingers for tool use and fine control

Secondary functions

  • Communicating through gesture and sign language
  • Bearing weight in pushing, climbing and falling
  • Sensing temperature, vibration and pain as a protective system
  • Contributing to balance and counterbalance during movement

Across a lifetime

Development
Hand development begins early in gestation, with fingers separating from paddle-like buds; grasp reflexes are present at birth and give way to voluntary control over the first year.
Childhood
Fine motor development proceeds from whole-hand grasp to pincer grip to writing control, and is a standard developmental milestone marker.
Adulthood
Grip strength typically peaks in the late twenties to thirties; overuse conditions such as tendinopathy and carpal tunnel syndrome emerge with occupational loading.
Later life
Grip strength declines measurably from midlife and is used clinically as a marker of sarcopenia and frailty; thumb-base and finger osteoarthritis become very common.
Sex differences
Carpal tunnel syndrome, thumb-base osteoarthritis and rheumatoid arthritis affecting the hands are all substantially more common in women.

Body connections

Grip strength has become one of the most useful single measurements in clinical medicine. It independently predicts cardiovascular events, disability and all-cause mortality across large international cohorts — not because grip itself is protective, but because it is an efficient proxy for total muscle mass, neurological integrity and overall physiological reserve.

Body connections

How this links to the rest of you

Arms & elbows

The muscles controlling the fingers originate at the elbow, which is why grip loading causes tennis and golfer's elbow.

Shoulders

Shoulder stability provides the base from which the hand is positioned; shoulder weakness increases distal compensation.

Neck & cervical spine

Cervical nerve root compression commonly presents as hand numbness or weakness, mimicking local nerve entrapment.

Brain

The hand occupies an outsized share of the motor and sensory cortex, and hand dexterity is a sensitive marker of neurological function.

Pancreas

Diabetes markedly increases the risk of carpal tunnel syndrome, trigger finger and Dupuytren's contracture.

How lifestyle changes it

Exercise

Grip and forearm training maintain hand strength; loaded carries and hanging are among the most efficient methods.

Nutrition

Protein sufficiency maintains the muscle mass that grip strength reflects; inflammatory arthritis is influenced by broader dietary patterns.

Hydration

No direct hand-specific role beyond general tissue health.

Sleep

Carpal tunnel symptoms classically wake people at night, and wrist position during sleep is a major contributor — night splinting is first-line treatment for this reason.

Stress

Stress increases forearm muscle tension and grip force during tasks, contributing to overuse symptoms.

Ageing

Grip strength declines steadily from midlife, and hand osteoarthritis becomes near-universal on imaging — though symptoms vary widely.

Environment

Vibrating tool use, forceful repetitive gripping and cold working conditions are the strongest occupational risk factors for hand and wrist disorders.

Genetics

Dupuytren's contracture has a strong hereditary component, and hand osteoarthritis clusters clearly in families.

Symptoms & conditions

Rare conditions

  • Complex regional pain syndrome
  • Kienböck's disease
  • Scaphoid non-union with avascular necrosis

Acute & chronic problems

  • Scaphoid fracture
  • Distal radius (Colles') fracture
  • Thumb ulnar collateral ligament tear (skier's thumb)
  • Mallet finger
  • Tendon laceration
  • Carpal tunnel syndrome
  • Thumb-base osteoarthritis
  • Trigger finger
  • De Quervain's tenosynovitis
  • Dupuytren's contracture
  • Raynaud's phenomenon

Early warning signs

  • Night-time hand numbness or tingling that you shake out
  • Dropping objects more often than before
  • Pain at the base of the thumb when gripping or opening jars
  • A finger catching or clicking as it straightens

Risk factors

  • Forceful repetitive gripping or vibrating tool use
  • Diabetes and thyroid disease
  • Pregnancy (for carpal tunnel)
  • Family history of Dupuytren's or hand osteoarthritis
  • Smoking, which worsens Raynaud's and healing

Protective factors

  • Regular grip and forearm training
  • Ergonomic tool and workstation setup
  • Task variation rather than sustained repetition
  • Warmth and glove use in cold conditions for Raynaud's

Optimise & recover

Prevention

  • Train grip directly — loaded carries, hangs and gripper work maintain the strength that declines with age
  • Vary tasks rather than sustaining a single repetitive hand position for hours
  • Set up keyboards and tools so the wrist stays near neutral rather than extended or flexed
  • Take microbreaks and stretch the forearms during long typing or manual sessions

Recovery

  • Use a neutral wrist night splint for carpal tunnel symptoms — the best-evidenced conservative first step
  • Load tendons progressively after tendinopathy rather than resting completely
  • Keep arthritic hands moving; structured hand exercise improves function even where imaging shows advanced change

Hand therapy is a specialist discipline for good reason: the structures are small, the tendon gliding relationships are precise, and outcomes after fracture or tendon injury depend heavily on early, correctly staged movement. For hand osteoarthritis, exercise programmes combined with joint protection education and, where relevant, thumb orthoses have reasonable trial support.

Movement library

  • Tendon gliding exercises

    A sequence of finger positions that moves the flexor tendons through full excursion, used in carpal tunnel and post-injury rehabilitation.

    Beginner
  • Wrist circles and controlled articular rotations

    Maintains wrist range in all directions, often lost with desk-based work.

    Beginner
  • Finger abduction and opposition drills

    Trains the intrinsic hand muscles responsible for fine control.

    Beginner
  • Farmer's carry

    The most efficient grip builder — heavy loaded walking trains grip endurance alongside the whole body.

    Beginner
  • Dead hang from a bar

    Builds grip strength and decompresses the shoulder simultaneously.

    Intermediate
  • Wrist flexion and extension curls

    Balances forearm strength, particularly important for people who only ever grip.

    Beginner
  • Putty or grip trainer squeezes

    Accessible resistance for hand strength, widely used in hand therapy.

    Beginner
  • Pinch grip holds

    Trains thumb strength specifically, relevant to thumb-base osteoarthritis prevention.

    Intermediate
  • Prayer stretch

    Lengthens the wrist flexors, commonly tight in typists and manual workers.

    Beginner
  • Reverse prayer or wrist extensor stretch

    Targets the extensor side, relevant to tennis elbow.

    Beginner

Self-massage of the forearm flexor and extensor masses eases the muscular component of hand overuse symptoms; direct massage over an inflamed tendon sheath is usually counterproductive.

Habits worth building

  • Add a heavy carry to your training week — it is the single most efficient grip intervention
  • Keep hands warm in cold weather if you have Raynaud's; the response is temperature-triggered
  • Rest your wrists in a neutral position at night if you wake with numbness

Nutrition, devices & products

Nutrition affects the hands mainly through two routes: maintaining the muscle mass that grip strength reflects, and managing inflammatory conditions such as rheumatoid arthritis where dietary pattern has modest but real effects.

Foods to prioritise

  • Adequate protein to preserve grip strength and muscle mass, especially after 50
  • Oily fish and an anti-inflammatory dietary pattern where inflammatory arthritis is present
  • Vitamin D and calcium for bone density, given the frequency of wrist fractures

Foods to limit

  • Smoking, which markedly worsens Raynaud's, healing and rheumatoid arthritis outcomes
  • Excess alcohol, associated with Dupuytren's contracture
SupplementEvidenceNote
Omega-3ModerateReasonable evidence for reducing joint tenderness in rheumatoid arthritis; little evidence for osteoarthritis.
Vitamin DModerateRelevant for bone density and fracture risk, particularly wrist fractures from falls.
Glucosamine and chondroitinLimitedWidely used for hand osteoarthritis, but trial evidence is inconsistent and generally unimpressive.

Devices & wearables

  • Neutral wrist night splints for carpal tunnel
  • Thumb-base orthoses for carpometacarpal osteoarthritis
  • Ergonomic keyboards and vertical mice
  • Therapy putty and grip trainers
  • Activity and typing-load trackers, useful mainly for identifying sustained repetitive exposure

Professional treatments

  • Specialist hand therapy
  • Nerve conduction studies for suspected carpal tunnel
  • Carpal tunnel decompression surgery for persistent or severe cases
  • Surgical release for trigger finger and Dupuytren's contracture

Educational mention only, not a recommendation: Topical NSAIDs, which are first-line for hand osteoarthritis with a good safety profile (clinician-guided), Corticosteroid injection for trigger finger and De Quervain's, Disease-modifying drugs where inflammatory arthritis is diagnosed.

When to seek medical care

Persistent night-time hand numbness, a finger that locks, or thumb-base pain limiting grip all warrant assessment — early treatment is more effective in each. Any wrist injury after a fall onto an outstretched hand should be examined even if movement is preserved, because scaphoid fractures are commonly missed and heal poorly if untreated.

Seek care promptly if you notice

  • Wrist pain in the hollow at the thumb side after a fall — possible scaphoid fracture even with normal X-rays
  • Persistent numbness with visible wasting of the muscle at the base of the thumb
  • Pale, cold, numb hand or fingers after injury
  • Deep wound with loss of finger movement or sensation
  • Rapidly spreading redness and swelling with fever, particularly after a puncture or bite
  • Severe escalating pain and tightness disproportionate to the injury

Research & frequently asked questions

Current research

  • Grip strength continues to be validated as a low-cost clinical biomarker of frailty and cardiovascular risk across large international cohorts.
    1

    The Lancet · 2015

    Prognostic value of grip strength: findings from the PURE study

    Prospective study across 17 countries found grip strength was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure.

  • Research is refining which carpal tunnel cases benefit from early surgery versus conservative management.
    2

    Cochrane Database of Systematic Reviews · 2012

    Non-surgical treatment (other than steroid injection) for carpal tunnel syndrome

    Review found evidence that wrist splinting, particularly at night, produces short-term symptom improvement compared with no treatment.

Emerging therapies

  • Enzyme injection (collagenase) as a non-surgical option for Dupuytren's contracture
  • Improved thumb-base joint replacement implants
  • Nerve transfer techniques for severe hand nerve injury

Scientific controversies

  • The strength of the association between keyboard use and carpal tunnel syndrome remains disputed, with most evidence pointing to forceful and vibratory work instead.
  • Whether grip strength adds prognostic information beyond simpler measures of muscle mass is debated.

The evolution of the human precision grip — enabled by a longer, more mobile thumb and a rotatable carpometacarpal joint — is one of the defining anatomical shifts of the hominin lineage, and fossil hand bones remain a primary line of evidence for when tool use began.

Frequently asked questions

Does cracking my knuckles cause arthritis?

No. Studies including long-term follow-up and one famous decades-long self-experiment have found no association between habitual knuckle cracking and osteoarthritis.

Why do my hands go numb at night?

The classic cause is carpal tunnel syndrome — wrist position during sleep compresses the median nerve. A neutral wrist night splint is the standard first-line treatment and is often effective.

Is grip strength really linked to how long I'll live?

It is a strong statistical predictor in large cohort studies, though as a proxy rather than a cause. It reflects total muscle mass, neurological function and general physiological reserve — which is why it is used clinically as a quick frailty marker.

Should I rest my hands if they hurt from typing?

Complete rest is rarely the answer. Varying tasks, adjusting wrist position toward neutral, taking microbreaks and strengthening the forearms usually work better than avoidance.

Can hand exercises help arthritis?

Yes. Structured hand exercise programmes improve grip strength and function in hand osteoarthritis, and joint protection education reduces symptom flares.

Explore further

Glossary

Carpal tunnel
The narrow passage at the wrist carrying the median nerve and finger flexor tendons.
Opposition
The thumb's ability to rotate and touch each fingertip — the basis of precision grip.
Scaphoid
A small wrist bone with a precarious blood supply, commonly fractured in falls and prone to non-union.
Trigger finger
A tendon catching in its sheath, causing a finger to lock and then snap straight.
Dupuytren's contracture
Progressive thickening of the palm's connective tissue, gradually bending fingers toward the palm.
Intrinsic muscles
The small muscles within the hand itself, responsible for fine positioning and control.

Trusted organisations & further reading

  • NHS — Carpal tunnel syndrome
  • Versus Arthritis
  • The HandFrank R. Wilson. An engaging account of how the hand shaped human cognition, culture and skill.
  • Rehab ScienceTom Walters. Practical rehabilitation programmes covering wrist and hand complaints.

Medical disclaimer

This page is for general education and does not replace personalised medical advice. If you have concerning symptoms, or before starting a new supplement, medication or exercise programme, speak with a qualified healthcare professional.