Axillary nerve of a person: structure, function and possible diseases
Axillary nerve and ray are the components of the posterior trunk of the brachial plexus. A nerve passes through the shoulder joint, giving a branch that innervates a small round muscle that rotates the arm outside. Further, the axillary nerve passes behind the lateral humerus before dividing into the posterior and anterior branches that supply a part of the deltoid muscle. To the posterior branch is the cutaneous nerve, which innervates the skin above the lateral surface of the deltoid muscle. Consider in more detail the axillary nerve. His anatomy is unique.
Most often, axillary nerve damage occurs when the humerus fracture or the dislocation of the shoulder. In some cases, only the axillary nerve is affected during idiopathic pleksopathy of the brachial plexus. What is the risk of axillary nerve damage? Let's look at this article.
The main clinical manifestation of the compression of the axillary nerve is a violation of the function of shoulder diversion due to weakness of the deltoid muscle. To withdraw the arm begins the supracutaneous muscle, and so the patient can retain a limited ability to withdraw his arm. And although a small round muscle may be weak, it is not always noticeable on a clinical examination as a result of the normal functioning of the subacute muscle.
The diagnosis can be confirmed only by revealing the weakness of the deltoid muscle and the abnormal EMG indices that are related to the small round and deltoid muscles. The SPNV of the axillary nerve when performing superficial records from the muscle( deltoid) serves as a means of detecting a delay in the potential or a decreased amplitude of the MTD of the axillary nerve.
Neuropathy of the upper extremity - is a common disease in the work of a neurologist. Damage can be as one axillary nerve, and several nerves at once, in connection with which the clinical picture of the disease will differ. Regardless of the reasons that caused the disease, the patient begins to feel pain, loss of sensitivity, a sense of discomfort and other characteristic symptoms.
Often, patients who experience neuropathy of the upper limbs feel that their problems are related to lack of sleep and fatigue, which can be restored with appropriate rest. Many reasons can lead to polyneuropathy of the hands. The most common are:
- Tumor diseases - where the tumors are not necessarily located in the area of the shoulder and armpit. Localization can be any.
- Operations carried out earlier( at the surgical site, the blood ceases to circulate normally, and this, in turn, contributes to muscle atrophy and edema, including compression of the nerve bundles, which leads to neuropathy).
- Long use of drugs containing chloroquine and phenytoin - these substances act negatively on nerve fibers.
- Injuries to the limbs, followed by the development of edema, compressing the nerve - as a consequence, neuropathy occurs.
- Various transferred infections, for example, tuberculosis, influenza, diphtheria, HIV, herpes, malaria and others.
- Regular supercooling - the body is very harmful to temperature reduction and prolonged exposure in this state.
- Deficiency of certain groups of vitamins in the body, often vitamin B.
- Irradiation - affects the body extremely negatively.
- Intoxication of the body.
- Excessive and strong physical exertion on the muscles.
- Endocrine diseases, diabetes mellitus including.
How does a damaged axillary nerve manifest itself?
Symptomatology can be divided into concomitant and basic. When the main symptoms are manifested, a person feels burning painful sensations that persecute him throughout the day, as well as a feeling of numbness in the fingers, hands in general, and a brush. With the concomitant symptomatology,
- appears to be difficult to move by hand;
- movement coordination disorder;
- involuntary muscle contractions, cramps, spasms;
- reduced temperature sensitivity;
- unpleasant sensations of goosebumps.
Damaged axillary nerve: diagnosis
To select the appropriate method of treatment, it is very important to conduct a thorough examination of the patient, make tests, take special tests, evaluate reflexes and muscle strength. Instrumental methods of diagnosis include: magnetic tomography, electroneuromyography.
These methods allow you to detect nerve damage, identify the cause and extent of conduction disorders. If necessary, the specialist can direct the patient to conduct additional tests to exclude another pathology. And only after the results can be diagnosed. It is very informative for the axillary nerve.
Neuropathy of the axillary nerve is accompanied by the restriction( impossibility) of the abduction of the shoulder, its movement back and forth, violation of the sensitivity of the innervation zone, atrophy of the deltoid muscle. Compression of the quadrilateral opening - tunnel syndrome of the axillary nerve( triceps, large and small round muscles, humerus).The pain is localized in the brachial region and is strengthened by rotation and deflection of the shoulder. Differentiation should be made from discogenic cervical sciatica and periarthritis periarthrosis.
Neuritis is a disease of the peripheral nerve( facial, intercostal, occipital, nerves of the extremities), which has an inflammatory character and manifests itself by pain along the nerve, muscle weakness of the innervated area, a sensitivity disorder. With the defeat of several nerves, the disease is called polyneuritis. The projection of the axillary nerve plays an important role here.
Nerve functions, area of innervation and degree of lesion determine the clinical picture of neuritis. In most cases, peripheral nerves consist of a different type of nerve fibers: vegetative, sensory, motor. For any type of neuritis, the symptoms are caused by the damage of each type of fiber:
- trophic and vegetative disorders cause the appearance of trophic ulcers, swelling, brittle nails, cyanotic skin, dry and thinning of the skin, depigmentation and local hair loss, sweating and so on;
- sensitivity disorders cause loss or decrease in the sensitivity of the innervation zone, paresthesia( sensation of chills, tingling sensation), numbness;
- impairment of movement activity causes loss or decrease of tendon reflexes, paresis( partial) or paralysis( complete) decrease in the strength of the innervated muscles, atrophy.
First signs of
Basically, the first signs of nerve damage are numbness and pain. The clinical picture of some types of neuritis demonstrates specific manifestations that are related to the area that the armpit nerve innervates.
Neuritis of the axillary nerve is expressed in the impossibility of raising the arm to the side, increasing the mobility of the shoulder joint, reduced sensitivity of the upper third of the shoulder, atrophy of the deltoid muscle.
Isolated axillary nerve is affected by injury to the brachial plexus or dislocation of the head of the shoulder. This leads to the loss of the raising of the hand to the horizontal level.
In a small strip of skin on the back of the upper arm, sensitivity is impaired. In some cases, the lateral cutaneous nerve of the forearm is injured and the sensitivity is disturbed on the outer-back, radial side of the forearm. All this is the nerves of the axillary region.
To quickly navigate in the defeat of the nerves of the upper limbs, especially the ulnar, median and ray, it will be enough to examine the patient for some typical movements of the fingers, hands and forearms. But to begin with it is necessary to be convinced of absence of obstacles of a mechanical nature to movement because of development of ankylosis or contractures. When the patient will perform the necessary movements, the specialist will need to be convinced of the safety of the strength and volume of these movements.
The next muscle group enters the motor innervation of the axillary( axillary) nerve:
Deltoid muscle C5-C6:
- During the contraction of the back, the lifted shoulder pulls back.
- During the contraction of the middle part, the shoulder is retracted to the horizontal plane.
- During the reduction of the front part, the upward lifted limb pulls forward.
Small round muscle C4-C5, contributing to the rotation of the shoulder outside.
To determine the strength of the deltoid muscle, you can conduct the following test: sitting or standing, the patient raises his hand to the horizontal level, and the doctor at this time is resisting this movement, palpating the contracted muscle.
When the axillary nerve is injured, the following occurs:
- Sensitivity on the surface of the shoulder( upper) is broken.
- Axillary nerve paralysis, atrophy of the deltoid muscle.
The symptom of the swallowtail is that the extension of the patient's hand is much less than healthy. And if you look at the patient from the side, you get the impression of a split swallowtail and a lag in the extension of the shoulder.