Elbow and forearm

Bones

The forearm consists of two long bones; the radius and the ulna. The ulna is located medially and is both longer and larger than the radius, which runs parallel to it laterally. These two bones are held together by the intervening interosseous membrane.

These forearm bones articulate with each other in two locations. The head of the radius forms a joint with the radial notch of the ulna proximally (proximal radioulnar joint), while the head of the ulna forms a joint with the ulnar notch of the radius distally (distal radioulnar joint). Alongside the humeroradial joint, the two radio-ulnar joints allow the pronation and supination movements of the forearm.

Practice and consolidate your knowledge with this interactive quiz about the radius and ulna.

Muscles

Just like the arm, the forearm is divided into two compartments by deep fascia; the interosseous membrane, and the fibrous intermuscular septa. This creates an anterior compartment that contains the flexor muscles, and a posterior one that contains the extensor muscles.

Extensors of the forearm

Residing in the posterior compartment of the forearm, the extensor muscles can be further divided into superficial and deep extensors.

Superficial extensors consist of seven muscles; brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, and the anconeus.

Deep extensors include five muscles; supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis.
This sound like a lot, right? Don’t worry, we have you covered with our comprehensive learning materials that help you expand and test your knowledge.

Flexors of the forearm

As seen in this forearm muscles diagram, the flexor muscles reside in the anterior compartment of the forearm, and are separated into the three following layers:

• Superficial layer: flexor carpi ulnaris, palmaris longus, flexor carpi radialis, and pronator teres.
• Intermediate layer: flexor digitorum superficialis, flexor digitorum profundus, and flexor pollicis longus.
• Deep layer: pronator quadratus.

Nothing makes the anatomy of the forearm flexors fun and easy-to-learn like our video tutorials, quizzes, and articles. Don’t miss checking them out in our study unit!

Mnemonics

The forearm muscles are responsible for flexion and extension of the wrist and digits. Remembering the action of each one can be quite difficult. Use the following mnemonic to make your life a little easier!

'Rule of 3s'

• 3 wrist flexors (flexor carpi radialis, flexor carpi ulnaris, palmaris longus)
• 3 finger flexors (flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus)
• 3 wrist extensors (extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris)
• 3 finger extensors (extensor digitorum, extensor indicis, extensor digiti minimi)
• 3 thumb extensors (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus)