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Tendon, Nerve or Muscle? The Forearm Is Where Hand Problems Start
Most forearm pain is overworked tendons or muscles from gripping, lifting or a new sport, and it settles over days to weeks once you cut back the load that provokes it. Where it hurts narrows it down. Just below the outer elbow bump: usually tennis elbow. Further down, deep in the muscle, not improving: often a trapped nerve. A forearm that’s swelling, tight and agonizing after an injury is an emergency.
Here’s something most people don’t realize.
Your fingers have no muscles in them. NONE. Every grip, every pinch, every finger you curl is powered by muscles in your forearm, pulling on long tendons (how the tendons work).
Which means the forearm takes the load for everything your hand does…and three major nerves run through it on their way to your fingers.
A lot of “hand” and “elbow” problems are really forearm problems wearing a disguise.
Guess wrong and you can spend months stretching a “tennis elbow” that was a nerve all along…or rest a forearm overnight that needed a surgeon by morning.
Press around with one finger of your other hand until you find the worst spot. Then find it below.
First: the ones that don’t wait
- After an injury or a crush, the forearm is swelling, tight and painful out of proportion, and it gets much worse when someone straightens your fingers: acute compartment syndrome. Emergency department NOW
- A fall, and the forearm looks bent or you can’t turn your palm up and down: a forearm fracture. X-ray today
- A pop at the front of the elbow while lifting, then bruising down the forearm: a distal biceps rupture. The repair window is weeks, not months
- Sudden weakness with no numbness, like you can’t lift your fingers or make an OK sign: AIN or PIN palsy. Get it assessed this week
Compartment syndrome is the one that can’t wait until morning. Pressure building inside the muscle can damage it within hours.
Outer forearm (the thumb side, back of the arm)
- Just below the outer bony bump of the elbow, worst gripping or lifting a mug: tennis elbow
- A few finger-widths further down, deep in the muscle, treated as tennis elbow for months with no change: radial tunnel syndrome. A nerve, not a tendon
- Lower down, a hand’s width above the wrist on the thumb side, sometimes with a squeak: intersection syndrome. Rowers, lifters, paddlers
- Can’t lift the fingers at the knuckles, but the wrist still lifts: a PIN palsy. Can’t lift the wrist either: a radial nerve palsy, and the wrist needs supporting (wrist drop splint)
(Quick test for the outer forearm: rest your forearm on a table, palm down, and lift the middle finger against the press of your other hand. Pain right at the outer elbow bump points to tennis elbow. Pain several centimeters further down in the muscle points to the radial tunnel.)
Inner forearm (the little-finger side)
- Just below the inner elbow bump, worst gripping and wringing: golfer’s elbow
- Aching down the inner forearm with tingling into the ring and little fingers: the ulnar nerve, usually squeezed at the elbow. Cubital tunnel syndrome
- Climbers with deep pain at the front of the elbow and upper forearm after hard pulling: climber’s elbow
Front of the forearm (palm side)
- Aching in the upper forearm, with numbness in the thumb, index finger AND the palm itself, but it doesn’t wake you at night: pronator teres syndrome. Worth raising before anyone books a carpal tunnel release
- Can’t make a neat OK sign with thumb and index tip, no numbness: an AIN palsy
- Numb fingers at night that ease when you shake the hand out: that’s further down, at the wrist. Carpal tunnel syndrome
The whole forearm
- Pumps up, goes tight and stops working at the same point in every session, then settles with rest: exertional forearm pain (arm pump). The timing is the diagnosis
- Aching after a big session of rowing, paddling or lifting: load. Rowing injuries and general overuse
- After a broken wrist or forearm, you can’t turn your palm up: can’t turn your palm up after a fracture. Rotation is the number to chase
- Tingling running the length of the forearm, with neck stiffness: the nerve may be pinched at the neck. Hand numbness from the neck
Pain you can press on is usually a tendon or muscle. Tingling and weakness you can’t press away is usually a nerve.
Popeye had giant forearms and spinach. You have the same forearm muscles as everyone else…so if they’re pumping up and quitting every session, that’s a sign, not a spinach deficiency.
How is forearm pain diagnosed?
Mostly with hands, not machines. A good assessment sorts tendon from nerve from muscle in about 20 minutes.
- Pressing and resisted tests. Exactly where it’s tender, and which movement against resistance reproduces it: lifting the wrist, lifting the middle finger, turning the palm up.
- Nerve checks. Sensation in each finger, tapping along the nerve’s path, and strength in the small muscles each nerve supplies.
- Grip strength. Measured, not guessed, and compared with the other side. It’s also how we track progress.
- X-ray. After a fall or a direct blow.
- Ultrasound or MRI. When a tendon tear or a lump needs a closer look.
- Nerve conduction studies. For suspected nerve compression. A normal result doesn’t rule out radial tunnel syndrome, which often tests normal.
- Compartment pressure testing. For suspected exertional compartment syndrome, measured before and after the activity that triggers it.
How long does forearm pain take to heal?
Depends entirely on which window your forearm is running on.
- Overuse ache or muscle strain: OPEN. Usually settles in 1 to 3 weeks once the load comes down.
- Tendon pain (tennis or golfer’s elbow): OPEN, but slow. Commonly 3 to 6 months with the right loading program. Ignored and kept on full load, it can drag on for a year or more.
- Trapped nerve with constant numbness or new weakness: CLOSING. Nerves tolerate pressure for a while, then start to lose fibers. Get assessed within weeks, not months.
- Broken forearm bone: commonly 8 to 12 weeks or more for the bone to unite, and longer for rotation and grip to return.
- Acute compartment syndrome: the window is HOURS. Muscle starved of blood doesn’t wait for a clinic appointment.
What can I do for forearm pain at home?
For the ordinary overuse kind, with no red flags and no numbness:
- Cut the provoking load, not all load. Find the one grip, lift or session that sets it off and halve it for 1 to 2 weeks. Total rest weakens the tendon you’re trying to calm down.
- Change the grip. Fatter handles, lifting with the palm facing up, two hands for the kettle.
- Isometric holds. Hold the wrist still against your other hand, or a light weight, for 30 to 45 seconds, 5 times, once or twice a day. Keep the pain at 3 out of 10 or below.
- Gentle stretch. Arm straight, gently bend the wrist down (outer forearm) or back (inner forearm) with the other hand. Hold 30 seconds, 3 times, twice a day. Mild pull, not pain.
- Give it 7 days. Better by day 7, keep going. Same or worse, get it assessed.
(If there’s numbness or tingling, skip the stretching until someone has checked the nerve. Stretching an irritated nerve tends to annoy it more.)
The short version
Just below the outer elbow: tennis elbow. Further down and deep, not improving: radial tunnel. Thumb side near the wrist with a squeak: intersection syndrome. Pumps up at the same point every session: arm pump. Swelling, tight and agonizing after an injury: emergency department, now.
Pain more at the elbow or the wrist? Elbow pain by location and wrist pain by location.
Get it checked if
- Numbness or tingling is constant, or spreading.
- You’re dropping things, or one hand is clearly weaker than the other.
- Pain wakes you at night, or aches when you’re resting.
- A lump in the forearm is growing.
- It’s no better after 7 days of cutting back the load.
And if the forearm is swelling, tight and painful out of proportion after an injury, don’t wait for any of the above. Go back to the top of this page: emergency department, now.
Where it hurts tells you the structure. How it behaves tells you how fast to move.
Written by Nigel Chua, hand occupational therapist in practice since 2005. Thousands of hands, wrists and elbows assessed and treated. My credentials are here. Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open. This page narrows the field; it doesn’t examine you. Forearm pain that isn’t clearly improving by day 7 needs assessing.