Anatomy
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What is the Anatomy of the Forearm?

Shelby Miller
Shelby Miller

The forearm is the lower portion of the arm, found between the elbow and wrist joints. Beneath the skin, and the fat stored just beneath the skin, are 20 muscles: eight in the palm side, and 12 in the back side. Supplying these muscles are several major arteries and nerves, namely the ulnar artery and median and ulnar nerves in the front compartment and the radial artery and radial nerve in the back compartment. The deepest structures in the forearm are the two long bones, the radius and ulna.

At the upper and lower ends of the forearm are the elbow and wrist joints, respectively. The elbow, which connects the tops of the radius and ulna and the bottom of the humerus in the upper arm, is a type of synovial joint known as a ginglymoid or hinge joint. Movements possible at the joint are flexion and extension, or the bending and straightening of the elbow.

The elbow joint, showing the ends of the radius and ulna.
The elbow joint, showing the ends of the radius and ulna.

The wrist is the connection between the radius and the carpal bones of the hand. It can produce the movements of flexion and extension, as well as adduction and abduction, or the waving of the hand from side to side. Two other joints are found between the wrist and elbow, the proximal and distal radioulnar joints, which are where the radius and ulna meet at their top and bottom ends and that permit rotation of the forearm.

Twelve muscles in the back compartment of the forearm are largely responsible for finger extension.
Twelve muscles in the back compartment of the forearm are largely responsible for finger extension.

In the front compartment of the forearm are eight muscles, all found on the palm side of the arm. These muscles are mostly responsible for flexion or curling inward of the hand and fingers as well as for pronation, the palm-down rotation of the arm. They include five superficial muscles, the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, pronator teres, and flexor digitorum superficialis, and three deep muscles, the flexor digitorum profundus, flexor pollicis longus, and pronator quadratus.

Wrist curls strengthen the muscles of the forearms.
Wrist curls strengthen the muscles of the forearms.

The back compartment of the forearm includes 12 muscles that are largely involved in the movements of extension or straightening of the wrist and fingers and the palm-up rotation of the arm. They include four superficial, two intermediate, and six deep muscles. The brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, and extensor carpi ulnaris are in the superficial compartment. The extensor digitorum and extensor digiti minimi are in the intermediate compartment. The abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis, supinator, and anconeus are in the deep compartment.

The ulnar, median, and radial nerves are the major nerves of the forearm.
The ulnar, median, and radial nerves are the major nerves of the forearm.

Supplying these muscles with essential nutrients and innervating them to produce movement and respond to external stimuli are several blood vessels and nerves, respectively. The front and back compartments of the forearm are distinguished from one another not by the location of the muscles and tendons contained within but by the blood vessels and nerves permeating each. In the anterior compartment, the major artery is ulnar artery, so named because it runs down the medial or ulnar side of the arm, the side of the pinky finger.

There are 20 muscles in the forearm.
There are 20 muscles in the forearm.

The major nerves of this compartment are the median nerve, which runs down the middle of the arm and enters the hand via the carpal tunnel in the wrist, and the ulnar nerve, which innervates the ulnar side of the arm. In the back compartment, blood is received from the radial artery, which is found along the lateral or radial side of the arm. The major nerve is the radial nerve, which is situated along the same side of the arm, that of the thumb.

Discussion Comments

mgraham7

Teaching the anatomy of the forearm to junior high students could involve exercising and range of motion activities. The health teacher could get permission to take the class to the gym or even outside to play a game of baseball or even volleyball. These sports use the forearm in serving in volleyball and in baseball throwing the ball and catching the ball.

In junior high, these students are still growing physically and emotionally and they learn through active participation and when teachers find an active way to teach didactic material, the students will understand concepts better.

CandyLady

Any thoughts on a good, simple method for teaching some of the basics of the forearm's anatomy to junior high kids? Supplying detailed information like this is great, but something more hands-on or graphically stimulating might be a helpful addition.

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    • The elbow joint, showing the ends of the radius and ulna.
      By: Alila
      The elbow joint, showing the ends of the radius and ulna.
    • Twelve muscles in the back compartment of the forearm are largely responsible for finger extension.
      By: gwolters
      Twelve muscles in the back compartment of the forearm are largely responsible for finger extension.
    • Wrist curls strengthen the muscles of the forearms.
      By: Monkey Business
      Wrist curls strengthen the muscles of the forearms.
    • The ulnar, median, and radial nerves are the major nerves of the forearm.
      By: 7activestudio
      The ulnar, median, and radial nerves are the major nerves of the forearm.
    • There are 20 muscles in the forearm.
      By: unclepodger
      There are 20 muscles in the forearm.
    • Physical therapy may be used to treat forearm injuries.
      By: WavebreakmediaMicro
      Physical therapy may be used to treat forearm injuries.
    • An X-ray may be required to diagnose fractures to the forearm where it meets the elbow joint.
      By: laurent dambies
      An X-ray may be required to diagnose fractures to the forearm where it meets the elbow joint.
    • The brachioradialis is a muscle in the forearm that flexes the arm at the elbow.
      By: high_resolution
      The brachioradialis is a muscle in the forearm that flexes the arm at the elbow.
    • Any part of the forearm is at risk of injury in a fall.
      By: waxart
      Any part of the forearm is at risk of injury in a fall.
    • The front and back compartments of the forearm are distinguished by the blood vessels and nerves permeating each side.
      By: Photographee.eu
      The front and back compartments of the forearm are distinguished by the blood vessels and nerves permeating each side.