Radial nerve

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Radial nerve is the largest branch of the brachial plexus (C5 to T1) and it carries both sensory and motor neurons fibers.



Radial Nerve Course


Origin[✎ edit | edit source]

The nerve has its origin in each one of the plexus nerve roots but arises mainly from the posterior cord and divides into two terminal branches, designated superficial and deep, that supply muscular and cutaneous branches to the posterior aspect of the arm and forearm.


Course[✎ edit | edit source]

After leaving the posterior cord of the brachial plexus it goes through the arm, first in the posterior compartment of the arm, and later in the anterior compartment, and continues in the posterior compartment of the forearm. The nerve ends in the dorsal part of the hand as a sensory nerve.


Innervation[✎ edit | edit source]

Radial Nerve innervates triceps brachii, supinator, anconeus, the extensor muscles of the forearm, and brachioradialis; about the cutaneous supply it innervates skin of the posterior arm as the dorsal cutaneous nerve of the arm, and also in the posterior region of the hand.



Pathologies and Complications[✎ edit | edit source]

Radial nerve dysfunction:


Radial nerve dysfunction is a problem with the radial nerve. Damage to the radial nerve leads to problems with movement or sensation of the back of the arm (triceps), forearm, or hand. Causes

Radial neuropathy occurs when there is damage to the radial nerve, which travels down the arm and controls movement of the triceps muscle at the back of the upper arm. It also controls the ability to bend the wrist backward and helps with the movement and sensation of the wrist and hand.

Mononeuropathy means a single nerve is damaged. With mononeuropathy, usually the nerve damage is caused locally. However, body-wide disorders may damage just one nerve.

Causes are:

Injury

       "Crutch palsy," caused by improper use of crutches
       Fracture of the humerus (upper arm bone)
       Long-term or repeated constriction of the wrist (for example, from wearing a tight watch strap)
       Pressure caused by hanging the arm over the back of a chair ("Saturday night palsy" if caused by drinking too much alcohol and falling asleep in that position)
       Pressure to the upper arm from arm positions during sleep or coma
       Pinching of the nerve during deep sleep, such as when a person is intoxicated
   Long-term pressure on the nerve, usually caused by swelling or injury of nearby body structures


Symptoms

The following symptoms may occur:

   Abnormal sensations
       Hand or forearm ("back" of the hand)
       "Thumb side" (radial surface) of the hand
       Fingers nearest to the thumb (2nd and 3rd fingers)
   Difficulty straightening the arm at the elbow
   Difficulty bending the hand back at the wrist, or even holding the hand
   Numbness, decreased sensation, tingling, or burning sensation
   Pain

Exams and Tests

The health care provider will take a detailed history to find out what you may have been doing just before the symptoms started, and to learn about any other medical problems you may have.

An exam of the arm, hand, and wrist may find:

   Decreased ability to extend the arm at the elbow
   Decreased ability to rotate the arm outward (supination)
   Difficulty lifting the wrist or fingers (extensor muscle weakness)
   Muscle loss (atrophy) in the forearm
   Weakness of the wrist and finger
   Wrist or finger drop

Tests may be needed, depending on the history, symptoms, and findings from the physical exam. Tests for nerve dysfunction may include:

   Different blood tests
   EMG
   MRI of the head, neck, and shoulder to look for other causes
   Nerve biopsy (rarely needed)
   Nerve conduction tests

Treatment

The goal of treatment is to allow you to use the hand and arm as much as possible. The health care provider should find and treat the cause, if possible. In some cases, no treatment is needed and you will recover slowly on your own.

Surgery to remove masses that press on the nerve may help.


REFERENCES[✎ edit | edit source]

GILROY / MACPHERSON / ROSS / SCHUENKE / SCHULTE / SCHUMACHER,. Atlas of Anatomy [online] 1st edition. June 2008. Available from <http://www.thieme.com/index.php?option=com_virtuemart&page=shop.product_details&flypage=flypage.tpl&product_id=242&Itemid=53>. ISBN 9781604060621.



[1] Image about Radial Nerve [2] Radial never dysfunction