Muscles in the Arm

By Amelia Son

Muscles in the Arm

Muscles in the back

Muscles in the back

The muscles of the arm can be broken into the upper arm, which is the space between the shoulder and the elbow, and the lower arm, which is the space between the elbow and the wrist.  The following will describe the muscles of both the upper and lower arm, their function, and common injuries.

The upper arm has four main muscles, three on the anterior (front) side, and one on the posterior (back) side.  They are as follows;

  • Biceps Brachii – Anterior
    • Located on the anterior side of the upper arm
    • Two-headed muscle that sits in front of your humerus bone
    • The biceps brachii rotates the forearm as well as flexes the arm at the elbow and shoulder
    • The most common injuries are strain to the biceps brachii and tearing of one of the two tendons that attach near the shoulder
  • Coracobrachialis – Anterior
    • Located under the biceps and closer to the humerus bone
    • This muscle lifts the arm from the shoulder and helps pull the arm back down to your side from a lifted position
    • The most common injuries are tendon ruptures
  • Brachialis – Anterior
    • Located under the biceps muscle but closer to, and crosses, the elbow joint
    • This muscle flexes the elbow
    • Common injuries are tendon ruptures which could decrease ability to bend at elbow
  • Triceps Brachii – Posterior
    • A three headed muscle that spans the back of the arm and crosses the elbow joint
    • This muscle straightens the arm at the elbow
    • Common injuries are muscle strains and tears

Muscles in the Forearm

There are many muscles in the forearm with many different purposes.  There are also layers to the anterior and posterior sides of the forearm and are known as the superficial, intermediate, and deep layers.  The following will describe the muscles in layer order;

  • Flexor carpi ulnaris – Anterior superficial
    • This muscle crosses the wrist joint
    • It flexes the wrist and pulls the hand towards your pinky
  • Plamaris longus – Anterior superficial
    • A muscle that not all people have in their wrist
    • It helps with flexion of the wrist
  • Flexor carpi radialis – Anterior superficial
    • This muscle crosses the wrist joint
    • It flexes the wrist and pulls the hand towards your thumb
  • Pronator teres – anterior superficial
    • This muscle crosses the wrist joint
    • It helps rotate your forearm so your palm is facing your body
  • Flexor digitorum superficialis – anterior intermediate
    • This muscle controls fingers
    • It flexes your second, third, fourth, and fifth fingers
  • Flexor digitorum profundus – anterior deep
    • This also crosses the wrist joint
    • Helps with flexion of your fingers and moving your wrist toward your body
  • Flexor pollicis longus – anterior deep
    • This muscle has one purpose – to flex your thumb
  • Pronator quadrature – anterior deep
    • This muscle assists with forearm rotation
  • Brachioradialis – posterior superficial
    • Closer to your elbow joint
    • Flexes your forearm at your elbow
  • Extensor carpi radialis longus – posterior superficial
    • Crosses the wrist joint closer to your thumb
    • Helps pull your wrist towards your thumb and extends your wrist
  • Extensor carpi radialis brevis – posterior superficial
    • Is a shorter and wider muscle than the longus mentioned above
    • Helps with pulling wrist towards thumb and wrist extension
  • Extensor digitorum – posterior superficial
    • Crosses the wrist in to the fingers
    • Extends your second, third, fourth, and fifth fingers
  • Extensor carpi ulnari – posterior superficial
    • This muscle pulls your wrist towards your pinky finger
  • Supinator – posterior deep
    • Spans the entire forearm
    • Helps forearm rotate so that your palm faces out
  • Abductor pollicis longus – posterior deep
    • Muscle of the hand
    • Moves your thumb out and away from your hand
  • Extensor pollicis brevis – posterior deep
    • Muscle of the hand
    • Extends your thumb away from your hand
  • Extensor pollicis longus – posterior deep
    • Longer counterpart of the brevis mentioned above
    • Assists with thumb extension
  • Extensor Indices – posterior deep
    • Spans the entire length of your forearm
    • Extends your index finger

With the majority of the muscles that cross into the hand and move the fingers, there are often injuries that are made from cutting or breaking of the wrist.  When this happens, surgery is common to repair the tendons and extensive hand therapy is required to reach full use.

JOI Fracture and Injury Care

JOI Physicians are currently offering ASAP fracture and injury care. Further, this is a new option for patients who would like to avoid the emergency room if they have suffered a fracture or soft tissue injury. To learn more about this service, read this article about fracture and injury care. Make an appointment by calling (904)JOI-2000.

Please do not hesitate to call JOI for your medical needs. Further, we have surgeons that can help diagnosis your tear and therapy staff waiting to help rehab you back to full health! Please call JOI-2000 or click the banner below to schedule with one of our specialists.

 

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Written by: Amelia Son

 


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