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Elbow and forearm: want to learn more about it?

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Elbow and forearm

Forearm - anterior viewExtending 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.

Key facts about the elbow and forearm
Forearm

Bones: radius, ulna

Joints: humeroradial, radioulnar joints (proximal, distal)

Muscles:

- 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)

Elbow joint

Bones: humerus, radius, ulna

Type: synovial, hinged joint

Ligaments: annular ligament and collateral (radial, ulnar) ligaments

Movements: 

- Flexion - biceps brachii, brachialis, brachioradialis muscles
- Extension - triceps brachii muscle

Forearm anatomy

Bones

Diagram showing the bones and ligaments of the forearm

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.

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.

Diagram of the forearm 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

Diagram of the forearm flexors

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:

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)

Elbow anatomy

Review of the elbow joint

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
Key Facts about elbow joint
Type Hinge joint
Bones Humerus, radius, ulna
Ligaments Ulnar collateral, radial collateral, annular, quadrate ligaments
Blood supply 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!

Elbow and forearm: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

Article, review and layout:

  • Sami Dai
  • Nicola McLaren
  • Jana Vasković

Illustrations:

  • Forearm (anterior view) - Yousun Koh
  • Forearm bones and ligaments (review) - Yousun Koh
  • Forearm extensor muscles (review) - Yousun Koh
  • Forearm flexor muscles (review) - Yousun Koh
  • Elbow joint (review) - Paul Kim
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