Elbow and forearm
Extending from the wrist to the elbow joint is the region of the upper extremity called the forearm (antebrachium). The forearm helps the shoulder and the arm in force application and the precise placement of the hand in space, with the help of the elbow and radioulnar joints.
This article is a guide to help you master the anatomy of the forearm and the elbow joint, using the beautiful content of Kenhub.
Bones: radius, ulna
Joints: humeroradial, radioulnar joints (proximal, distal)
- Extensors: superficial (brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, and the anconeus) and deep (supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis)
- Flexors: superficial (flexor carpi ulnaris, palmaris longus, flexor carpi radialis, and pronator teres), intermediate (flexor digitorum superficialis, flexor digitorum profundus, and flexor pollicis longus) and deep (pronator quadratus).
Mnemonic: 'Rule of 3s' (3 wrist flexors, 3 finger flexors, 3 wrist extensors, 3 finger extensors, 3 thumb extensors)
Bones: humerus, radius, ulna
Type: synovial, hinged joint
Ligaments: annular ligament and collateral (radial, ulnar) ligaments
- Flexion - biceps brachii, brachialis, brachioradialis muscles
- Extension - triceps brachii muscle
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.
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.
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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!
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)
The elbow joint is a synovial joint that connects the arm and the forearm, providing 150 ْ of extension-flexion movement. It consists of three joints; the humeroulnar joint, the humeroradial joint, and the proximal radioulnar joint, all within one articular capsule!
The elbow joint is supported by three ligaments:
- The annular ligament
- The radial collateral ligament
- The ulnar collateral ligament
|Bones||Humerus, radius, ulna|
|Ligaments||Ulnar collateral, radial collateral, annular, quadrate ligaments|
Proximal to elbow joint - ulnar collateral, radial collateral, middle collateral arteries
Distal to elbow joint - radial recurrent, ulnar recurrent arteries
|Movements||Flexion - biceps brachii, brachialis, brachioradialis muscles
Extension - triceps brachii muscle
|Clinical||Fractures, epicondylitis, arthritis, venipunctures|
Watching our videos and taking our quizzes on the elbow joint will guarantee you an all-inclusive understanding of this topic with these learning materials.
Finish this lecture about the bones, joints, muscles, nerves and vessels of the forearm with a specially designed quiz that covers it all!