Corpus
Upper body

Arms & Elbows

A hinge with a rotational twist — the linkage that turns shoulder power into hand precision.

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

3 (humerus, radius, ulna)

Bones

≈0–145°

Elbow flexion range

≈180° total

Forearm rotation

Fewer than 1 in 20 cases

Tennis elbow in tennis players

Overview

The arm is a two-segment linkage connecting the shoulder to the hand. The upper arm has a single bone, the humerus; the forearm has two — the radius and ulna — running in parallel, and it is their ability to cross over one another that lets you turn your palm up and down without moving your shoulder. That rotation, called
pronation and supinationRotating the forearm palm-down and palm-up respectively.
, is what makes a screwdriver, a door handle and a doorknob usable. The elbow itself is not a simple hinge: it combines a hinge joint for bending with a pivot joint for rotation, and it is crossed by the tendons that control the entire hand. Because those tendons originate at the elbow's bony prominences, hand and grip loading is felt at the elbow — which is why the most common elbow complaints are named for sports most sufferers do not play.

Interesting facts

  • The 'funny bone' is not a bone at all — it is the ulnar nerve running in a shallow groove behind the elbow, exposed enough to be struck directly.
  • The large majority of people diagnosed with tennis elbow have never played tennis; manual work and computer use account for far more cases.
  • Biceps brachii is a weaker elbow flexor than brachialis, which lies beneath it and does most of the work — biceps is primarily a supinator.
  • The forearm's radius rotates around the fixed ulna, which is why your palm can turn while your elbow stays still.
  • Elbow dislocation is the second most common major joint dislocation in adults, after the shoulder.

Common misconceptions

  • Tennis elbow is an inflammatory condition treated by rest and anti-inflammatories.
    It is primarily a degenerative tendon change rather than inflammation. Progressive loading, particularly eccentric and heavy slow resistance, has better evidence than rest or corticosteroid injection at one year.
  • Corticosteroid injection is the best treatment for tennis elbow.
    It relieves pain in the short term but trials consistently show worse outcomes at one year than exercise or even watchful waiting.
  • Big biceps come from curls alone.
    Brachialis and brachioradialis contribute substantially to upper arm size, and are loaded better by hammer and reverse-grip variations than standard curls.
  • Elbow pain means you should stop gripping things.
    Graded grip and wrist loading is the treatment. Complete avoidance deconditions the tendon and prolongs symptoms.

Anatomy & how it works

Three bones, two functional joints and two tendon origins that carry the load of everything the hand does.

  • Humerus

    The single upper arm bone, running from shoulder to elbow.

  • Radius and ulna

    The two forearm bones; the radius rotates around the ulna to produce palm-up and palm-down positions.

  • Humeroulnar joint

    The hinge component of the elbow, providing bending and straightening.

  • Proximal radioulnar joint

    The pivot allowing forearm rotation.

  • Lateral epicondyle

    The bony prominence on the outer elbow where the wrist extensor tendons originate — the site of tennis elbow.

  • Medial epicondyle

    The inner elbow prominence where the wrist flexor tendons originate — the site of golfer's elbow.

  • Biceps, brachialis and triceps

    The main movers: biceps and brachialis flex the elbow, triceps extends it, and biceps also supinates the forearm.

  • Ulnar nerve

    Runs superficially behind the medial elbow through the cubital tunnel, vulnerable to compression and direct impact.

The elbow is best understood as a positioning system rather than a power source. The shoulder provides gross placement, the elbow sets distance and orientation, and the forearm rotation aligns the hand for the task. What makes it clinically distinctive is that the muscles moving the wrist and fingers originate at the elbow, so every act of gripping puts tensile load through tendons anchored to the epicondyles. Repeated forceful gripping — with tools, keyboards, racquets or weights — concentrates that load at a small tendon origin, which is the mechanism behind both tennis and golfer's elbow.

Primary functions

  • Bending and straightening the elbow to position the hand in space
  • Rotating the forearm to turn the palm up or down
  • Transmitting force between shoulder and hand during pushing, pulling and carrying

Secondary functions

  • Anchoring the muscles that control the wrist and fingers
  • Contributing to throwing velocity through the kinetic chain
  • Providing shock absorption when catching or bracing

Across a lifetime

Development
The elbow's growth centres appear and fuse in a well-defined sequence used clinically to interpret children's elbow X-rays.
Childhood
Pulled elbow — a partial dislocation of the radial head from a sudden tug on the arm — is common in toddlers and resolves immediately with a simple reduction manoeuvre.
Adulthood
Tennis and golfer's elbow peak between 35 and 55, most often in manual workers and desk-based computer users rather than athletes.
Later life
Elbow osteoarthritis is comparatively uncommon, but cubital tunnel syndrome and reduced extension range become more frequent; upper arm muscle mass declines with age.
Sex differences
Women have a slightly greater carrying angle at the elbow on average; tennis elbow incidence is broadly similar across sexes.

Body connections

Elbow and arm function determine whether you can carry, lift, reach and self-care independently. Persistent tennis elbow is one of the most common causes of upper-limb work absence, and upper arm muscle mass contributes to the overall lean mass that predicts metabolic and functional health.

Body connections

How this links to the rest of you

Hands & wrists

The muscles controlling the fingers originate at the elbow, so grip demand is transmitted directly to the epicondyles.

Shoulders

Shoulder stability determines how much load the elbow absorbs — weak scapular control increases distal strain in throwing and lifting.

Neck & cervical spine

Cervical nerve root irritation refers pain and weakness into the arm, frequently mistaken for a local elbow problem.

Upper back

Mid-back strength provides the stable base from which arm force is generated during pulling and pressing.

How lifestyle changes it

Exercise

Progressive resistance training builds both arm strength and tendon load tolerance — the latter being the actual protection against epicondylalgia.

Nutrition

Adequate protein supports muscle and tendon collagen turnover; nothing arm-specific applies.

Hydration

No direct effect beyond general tissue health.

Sleep

Sleeping with the elbow fully bent compresses the ulnar nerve and is a common cause of waking with a numb little finger.

Stress

Increased grip force during stressful tasks contributes measurably to forearm tendon loading.

Ageing

Tendon collagen turnover slows with age, which is part of why epicondylalgia takes longer to resolve in older adults.

Environment

Vibrating tools, forceful repetitive gripping and non-neutral wrist positions at a desk are the dominant occupational risks.

Genetics

Tendon collagen composition varies genetically and influences susceptibility to tendinopathy, though not to a clinically actionable degree.

Symptoms & conditions

Common conditions

Rare conditions

  • Elbow osteochondritis dissecans
  • Radial tunnel syndrome
  • Elbow osteoarthritis

Acute & chronic problems

  • Elbow dislocation
  • Distal biceps tendon rupture
  • Olecranon fracture
  • Pulled elbow in young children
  • Lateral epicondylalgia (tennis elbow)
  • Medial epicondylalgia (golfer's elbow)
  • Cubital tunnel syndrome
  • Olecranon bursitis

Early warning signs

  • Pain on the outer elbow when gripping or lifting a kettle
  • Weak grip that fatigues faster than usual
  • Tingling in the ring and little fingers, especially with the elbow bent
  • Aching after a day of tool or mouse use

Risk factors

  • Repetitive forceful gripping
  • Vibrating tool use
  • Sudden increases in racquet, climbing or lifting volume
  • Previous epicondylalgia
  • Diabetes and smoking, which impair tendon healing

Protective factors

  • Progressive grip and wrist strength training
  • Task variation and microbreaks
  • Correct racquet grip size and technique in sport
  • Gradual load progression

Optimise & recover

Prevention

  • Build wrist extensor and flexor strength deliberately, not just biceps and triceps
  • Increase gripping-heavy training — climbing, rowing, deadlifts — in gradual steps
  • Vary mouse and tool positions rather than sustaining one grip for hours
  • Check racquet grip size and string tension if you play racquet sport

Recovery

  • Start with isometric wrist extensor holds, which reduce pain and permit early loading
  • Progress to eccentric or heavy slow resistance over 8–12 weeks
  • Modify rather than eliminate provocative activities — reduce grip force and duration first

Lateral epicondylalgia rehabilitation follows the tendon model: load the tendon progressively rather than resting it. Trials consistently show that exercise-based programmes outperform corticosteroid injection at one year, and that injection, despite better short-term pain relief, is associated with higher recurrence rates. Recovery is typically measured in months.

Movement library

  • Forearm pronation and supination with a light weight

    Maintains rotational range and loads the forearm rotators through their arc.

    Beginner
  • Elbow controlled articular rotations

    Takes the elbow and forearm through full available range to preserve mobility.

    Beginner
  • Ulnar nerve glides

    Reduces nerve tension in cubital tunnel syndrome when performed gently and without provoking symptoms.

    Intermediate
  • Eccentric wrist extension

    The core exercise for tennis elbow, lowering a light weight slowly with the palm facing down.

    Beginner
  • Eccentric wrist flexion

    The equivalent for golfer's elbow, loading the flexor origin at the inner elbow.

    Beginner
  • Hammer curl

    Loads brachialis and brachioradialis, which contribute more to arm size and elbow flexion strength than biceps alone.

    Beginner
  • Close-grip press or dip

    Builds triceps, the largest muscle of the upper arm.

    Intermediate
  • Chin-up

    Trains elbow flexors under substantial load alongside the whole upper back.

    Intermediate
  • Wrist extensor stretch

    Gently lengthens the tendons at the lateral epicondyle; used symptomatically rather than as treatment.

    Beginner
  • Wrist flexor stretch

    Targets the medial elbow tendon origin.

    Beginner

Soft tissue work to the forearm extensor mass provides short-term relief in tennis elbow. Direct deep pressure over the tender epicondyle itself is often provocative and adds little.

Habits worth building

  • Carry bags with the palm facing up rather than down when your outer elbow is sore — it offloads the extensor tendons
  • Avoid sleeping with the elbow fully bent if you wake with little-finger numbness
  • Reduce grip force on the mouse and tools; most people grip far harder than the task requires

Nutrition, devices & products

Arm nutrition is muscle and tendon nutrition. Protein sufficiency supports both, and vitamin C is required for the collagen synthesis that tendon remodelling depends on — relevant given how slowly epicondylalgia resolves.

Foods to prioritise

  • 1.4–2.0 g protein per kg body weight when training for arm strength or size
  • Vitamin C for collagen synthesis
  • Adequate total energy to support training adaptation

Foods to limit

  • Smoking, which measurably impairs tendon healing
  • Excess alcohol, which blunts post-training muscle protein synthesis
SupplementEvidenceNote
Creatine monohydrateStrongWell-supported for strength and lean mass gains across upper-body training.
Collagen peptides with vitamin CEmergingSome evidence for supporting tendon collagen synthesis when taken before loading exercise.
Protein supplementationStrongEffective for meeting protein targets, with no advantage over food if intake is adequate.

Devices & wearables

  • Counterforce elbow straps, which offer modest short-term symptom relief
  • Light dumbbells or a rehabilitation bar for eccentric wrist work
  • Vertical mice and ergonomic tool grips
  • Elbow padding for olecranon bursitis
  • Grip-force and activity sensors, used mainly in occupational assessment

Professional treatments

  • Physiotherapy-led progressive loading programmes
  • Shockwave therapy for recalcitrant epicondylalgia
  • Nerve conduction studies for suspected cubital tunnel syndrome
  • Surgical release or repair in persistent or ruptured cases

Educational mention only, not a recommendation: Topical NSAIDs for short-term symptom relief (clinician-guided), Corticosteroid injection, effective short-term but associated with worse one-year outcomes in tennis elbow.

When to seek medical care

Gradual-onset elbow pain related to gripping usually responds to a loading programme, though it may take months. Seek prompt assessment for deformity after injury, a sudden pop at the front of the elbow with weakness turning the palm up, or persistent numbness — distal biceps ruptures and nerve compression both do better with early treatment.

Seek care promptly if you notice

  • Visible deformity or inability to move the elbow after a fall
  • Sudden pop at the front of the elbow with bruising and weakness in supination
  • Persistent numbness or weakness in the hand, or visible muscle wasting
  • Hot, red, swollen elbow with fever
  • Cold, pale hand with elbow injury

Research & frequently asked questions

Current research

  • Research continues to define optimal loading dosage and duration for lateral epicondylalgia, where recovery is slow and relapse common.
    1

    The Lancet / BMJ follow-up analyses · 2002

    Corticosteroid injections, physiotherapy, or a wait-and-see policy for lateral epicondylitis

    Randomised trial found injection gave superior short-term relief but substantially higher recurrence and worse outcomes at 52 weeks than physiotherapy or watchful waiting.

  • Work is ongoing into why corticosteroid injection produces worse long-term outcomes despite short-term relief.
    2

    British Journal of Sports Medicine · 2019

    Tendinopathy management review

    Review synthesising tendon research supports progressive mechanical loading as first-line treatment across tendinopathies, with rest and anti-inflammatory approaches now considered inadequate.

Emerging therapies

  • Platelet-rich plasma injection for chronic epicondylalgia, where evidence remains mixed
  • Ultrasound-guided percutaneous tenotomy
  • Blood flow restriction training for early-stage arm rehabilitation

Scientific controversies

  • The value of platelet-rich plasma for tennis elbow is contested, with several well-designed trials showing no advantage over placebo.
  • Whether counterforce bracing changes outcomes or only perception of symptoms is unresolved.

Tennis elbow was described in the German medical literature in 1873 as 'lawn tennis arm', and the twentieth-century assumption that it was inflammatory persisted until histological studies from the 1970s onward showed degenerative rather than inflammatory tissue — a reclassification that redirected treatment from rest and anti-inflammatories to progressive loading.

Frequently asked questions

Why is it called tennis elbow if I don't play tennis?

The name reflects where it was first described, not who gets it. Fewer than one in twenty cases occurs in tennis players — manual work, tool use and computer work account for the large majority.

How long does tennis elbow take to get better?

Typically several months. Most cases resolve eventually, but progressive loading over 8–12 weeks or longer produces better and more durable results than rest, and relapse is common if the programme is stopped early.

Should I get a steroid injection for elbow pain?

It provides good short-term relief, but multiple trials show worse outcomes at one year compared with exercise or even doing nothing. It is generally reserved for cases where pain prevents starting a loading programme at all.

Why does my little finger go numb?

That distribution suggests ulnar nerve irritation, most often at the cubital tunnel behind the elbow. Sleeping with the elbow bent and leaning on the elbow are common contributors, and both are modifiable.

Do curls make the biggest difference to arm size?

Triceps make up the majority of upper arm mass, so pressing and extension work matters more than most people assume. For elbow flexors, hammer and reverse-grip variations recruit brachialis and brachioradialis, which standard curls under-load.

Explore further

Glossary

Lateral epicondyle
The bony prominence on the outer elbow where the wrist extensor tendons attach.
Medial epicondyle
The inner elbow prominence where the wrist flexor tendons attach.
Pronation and supination
Rotating the forearm palm-down and palm-up respectively.
Cubital tunnel
The passage behind the inner elbow through which the ulnar nerve runs.
Epicondylalgia
Pain at an epicondyle from tendon degeneration — the preferred term over 'epicondylitis', since inflammation is usually absent.
Brachialis
The elbow flexor lying beneath biceps, which does most of the actual bending work.

Trusted organisations & further reading

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.