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 in days to weeks with less of the provoking load. Where it sits narrows it down. Just below the outer elbow bump: usually tennis elbow. A few finger-widths further down, deep in the muscle, and not getting better: often a trapped nerve. Pumps up and stops working at the same point in every session: exertional forearm pain. And a forearm that’s swelling, tight and agonizing after an injury, worse when the fingers are stretched, 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.
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.
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.
Improving by day 7, let it finish. Same or worse at day 7, get it assessed. Pain more at the elbow or the wrist? Elbow pain by location and wrist pain by location.
Found your spot? Next question is how long you’ve got. The Closing Window Chart just below maps 15 hand, wrist and elbow conditions: open, closing, shut, plus the red flags. One page, free.
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.