Radial nerve: what it is, where it passes and works

Hi. Bend your wrist. He spreads his fingers. You probably could have done it easily. And that’s because your brain sent the relevant information to the muscles in your arm, wrist, and hand for it. This transmission was carried out through a series of nerves, which connect the rest of the nervous system to the muscles. One of them, of great importance for the movement and sensitivity of the limbs, is the radial nerve. It is on this nerve that we will speak next.

    The radial nerve: description and location

    It is called the radial nerve, one of the most important bundles of nerve fibers in controlling the upper limbs, being a peripheral nerve of the autonomic nervous system.

    It is one of the three main nerves that innervate the upper limbs, with ulnar and middle nerves.

    The radial nerve innervates muscles as relevant as the triceps or anconeum, or the brachialis and brachiorradialis. Also, among others, the extensors of the fingers, including the index and thumb. It is therefore a nerve of great importance to human beings. But not only that, it also has connections with the skin nerves and enables sensitivity and tactile perception in the innervating area.

      Areas crossed and its two main branches

      The nerve in question it originates in the brachial plexus, just behind the axillary artery. After that, go through the armpit, then move down the arm and forearm, hands and fingers. It should also be noted that there are two radial nerves, one in each of the body halves.

      It crosses the anterior compartment of the arm, passing around the spiral groove of the humerus (the rupture could affect the nerve) and after that it crosses the elbow and reaches the forearm, where it will divide into a shallow branch and another deep.

      The deep branch passes through the supinator muscle, enters the forearm and reaches the wrist from the back. This branch is related to muscle perception and the ability to stretch and stretch innervated muscles.

      The superficial branch of the radial nerve acts at the level of the skin, affecting the sensitivity of the upper limbs. This is subdivided into three cutaneous nerves: posterior of the arm, posterior of the forearm and lateral of the arm. It is also useful. This branch allows the cutaneous perception of the back of the forearm, the upper part of the arm, the back of the hand and the first four fingers.

      Functions of this nerve

      Our arms and especially our hands are fundamental elements for human beings because thanks to them we can develop a large number of activities, from defense or food to the manufacture of complex instruments and technologies. Its control is therefore of great relevance.

      The functions of the gen radial nerve are very broad, and highlight the interesting fact that it plays a role in both sensory perception and motor control.

      At the sensory level it allows the sensitivity and perception of the back of the arm and the forearm, including the elbows and wrists, as well as part of the hand (specifically allows the sensitivity of the back of the hand ) and a large part of the fingers (except small and part of the ring).

      At the motor level, it allows the extension of the fingers, wrist and arm. Its action is particularly relevant on the posterior forearm, By innervating the muscles of the posterior compartment (allowing extension of the wrist and fingers) the upper arm (by innervating the triceps brachii).

      Radial injuries

      Considering the general functions of this nerve, it can be easy to guess the effects that its injury can have: loss of feeling in much of the posterior area of ​​the arm, on the back of the hand and even in the fingers and the loss of the city to do a lot of movement.

      If this nerve is injured in the armpit, the ability to extend the arm, wrist, or fingers is lost, leaving the triceps and other nerves paralyzed, as well as non-tactile perception of much of the arm and back. .

      In the event that the injury occurs at the level of the humerus, there will be a decrease in the strength of the triceps and the wrist and the fingers will cease to be able to extend and the perception of the back of the hand, the wrist and the body. back of the forearm. Also called general wrist drop, which leads to loss of coordination and difficulty closing the hand.

      If the injury occurs in the superficial branch, the ability to move the entire area will remain intact, but the sensitivity of the wrist, hand and fingers will be lost.

      These alterations can occur due to a large number of factors and produce either through lacerations and injuries, pinching or myelination problems. Examples of elements that can cause them are neuropathies such as diabetes, fractures of the humerus or radius, dislocations, intoxication, wrist pressure, continuous enchantment, and lack of movement or d ‘inflammation.

      Bibliographical references:

      • Brazis, P., Biller, J. and Masdeu, J. (Eds) (2007). Peripheral nerves. In: Localization in clinical neurology: 27-72. Philadelphia: Lippincott Williams and Wilkins.
      • Ricci, FP, Barbosa, RI, Elui, VM, Barbieri, CH, Mazzer, N. & Fonseca, MC (2015). Radial nerve injury associated with humeral shaft fracture: retrospective study. Acta Ortop Bras, 23 (1): 19-21.

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