• 20 muscles
  • Checked September 2026

Forearm Muscles Quiz

Name the muscles of the forearm, flexors on the front and extensors on the back, layer by layer.

Forearm Muscles Quiz

Name Date

Tap the pronator teres

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Write the name of each numbered muscle.Answer key

  1. Brachioradialis
  2. Pronator teres
  3. Flexor carpi radialis
  4. Palmaris longus
  5. Flexor digitorum superficialis
  6. Flexor carpi ulnaris
  7. Flexor digitorum profundus
  8. Flexor pollicis longus
  9. Pronator quadratus
  10. Extensor carpi radialis longus
  11. Extensor carpi radialis brevis
  12. Extensor digitorum
  13. Extensor digiti minimi
  14. Extensor carpi ulnaris
  15. Anconeus
  16. Supinator
  17. Abductor pollicis longus
  18. Extensor pollicis brevis
  19. Extensor pollicis longus
  20. Extensor indicis

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a muscle is answered.

Next step Next: the muscles from shoulder to elbow

All 20 muscles on the diagram

Show the list

Front, surface 6

  1. Brachioradialis It bends the elbow, yet starts where the extensors start. It starts on the humerus above the elbow and ends at the far end of the radius.
  2. Pronator teres It turns the forearm so the palm faces down. Two heads, one from the inner bump of the humerus and one from the ulna, cross to the middle of the radius.
  3. Flexor carpi radialis It bends the wrist and tilts it toward the thumb side. From the inner bump of the humerus to the bases of the second and third hand bones.
  4. Palmaris longus A slim muscle that bends the wrist. Its long tendon ends in the tough sheet of the palm. Some people do not have one.
  5. Flexor digitorum superficialis The only muscle of the middle layer. It has two heads and splits into four tendons, which pass through the carpal tunnel to the middle bone of each finger. It bends the fingers.
  6. Flexor carpi ulnaris It bends the wrist and tilts it toward the little-finger side. Two heads, from the humerus and from the ulna at the elbow, run to the pisiform bone of the wrist.

Front, deep 3

  1. Flexor digitorum profundus The only muscle that can bend the last joint of the fingers. It starts on the ulna and splits into four tendons, which cross the carpal tunnel to the last bone of each finger.
  2. Flexor pollicis longus It bends the thumb. It starts on the front of the radius and ends on the last bone of the thumb.
  3. Pronator quadratus A square muscle that lies under the long tendons. It runs from the front of the ulna across to the front of the radius and turns the palm down.

Back, surface 6

  1. Extensor carpi radialis longus With the brevis it straightens the wrist. They also tilt it toward the thumb side. It starts on the ridge of the humerus above the outer bump of the elbow.
  2. Extensor carpi radialis brevis It lies beside the longus and starts lower. It starts on the outer bump of the humerus. The two tendons end on the second and third hand bones.
  3. Extensor digitorum The main muscle that straightens the fingers. It starts on the outer bump of the humerus, and its tendon splits into four, one to each finger.
  4. Extensor digiti minimi It straightens the little finger. A slim muscle beside the extensor digitorum. In some people the two are joined.
  5. Extensor carpi ulnaris It straightens the wrist and tilts it toward the little-finger side. From the outer bump of the humerus and the back of the ulna to the base of the fifth hand bone.
  6. Anconeus A small muscle that helps straighten the elbow. It runs from the outer bump of the humerus to the point of the elbow. Its fibers blend with the triceps.

Back, deep 5

  1. Supinator It turns the forearm so the palm faces up. Two heads, from the outer bump of the humerus and from the ulna, wrap onto the radius.
  2. Abductor pollicis longus It moves the thumb out, away from the hand. It lies just below the supinator and ends on the base of the first hand bone, at the root of the thumb.
  3. Extensor pollicis brevis It straightens the thumb at its lower joints. It lies beside the abductor pollicis longus and ends on the first bone of the thumb itself.
  4. Extensor pollicis longus A bigger belly than the brevis. Its tendon hooks round a bump on the radius at the wrist, like a rope round a pulley, and ends on the last bone of the thumb.
  5. Extensor indicis It lets the index finger straighten on its own. It starts on the ulna, farther down than the extensor pollicis longus.

How this list was compiled: Every name and detail line was checked on 2026-09-30 against Gray, Anatomy of the Human Body, 20th edition, 1918 (public domain), the chapter on the muscles of the forearm, https://archive.org/details/anatomyofhumanbo00grayrich; TeachMeAnatomy, Muscles in the Anterior Compartment of the Forearm, https://teachmeanatomy.info/upper-limb/muscles/anterior-forearm/, and Muscles in the Posterior Compartment of the Forearm, https://teachmeanatomy.info/upper-limb/muscles/posterior-forearm/; and Kenhub, Elbow and forearm, https://www.kenhub.com/en/library/anatomy/elbow-and-forearm. The wording is in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work

How it works

A right forearm from elbow to hand, drawn four times: the front and the back, each at the surface and again with the top layer removed. Name all twenty and you have the muscles in the forearm labeled.

Read the full guide

Front: flexors and pronators

At the surface, from the thumb side: brachioradialis, pronator teres, flexor carpi radialis, palmaris longus and flexor carpi ulnaris, with flexor digitorum superficialis showing between them. Under them lie flexor digitorum profundus, flexor pollicis longus and the square pronator quadratus.

Back: extensors and the supinator

The third drawing is a posterior forearm muscles quiz: two radial wrist extensors, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris and, at the elbow, anconeus. The fourth is for a lab sheet that says label the deep forearm muscles posterior view: supinator, three thumb muscles and extensor indicis.

  • Four surface flexors share one tendon on the inner bump of the elbow. Four surface extensors share one on the outer bump.
  • Flexor digitorum profundus is the only muscle that can bend the last joint of the fingers.
  • Brachioradialis starts where the extensors start, but it bends the elbow.

Questions and answers

What are the muscles of the forearm?

Twenty. Eight are on the front: four at the surface, flexor digitorum superficialis in a middle layer and three deep ones. Twelve are on the back: seven at the surface, counting brachioradialis and anconeus, and five deep ones.

What are the deep muscles of the posterior forearm?

Five: supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis. All but the supinator move the thumb or the index finger.

What is the difference between flexor digitorum superficialis and profundus?

Superficialis lies nearer the surface and its tendons end on the middle bone of each finger. Profundus lies deeper, on the ulna, and its tendons go on to the last bone, so only it can bend the last joint.

Which forearm muscles move the thumb?

Four long ones: flexor pollicis longus on the front, and abductor pollicis longus, extensor pollicis brevis and extensor pollicis longus on the back. Pollicis in a name means the muscle belongs to the thumb.

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