The axillary nerve and radial are the components of the posterior trunk of the brachial plexus. Under the shoulder joint, a nerve passes, giving a branch that innervates the small round muscle, which rotates the arm outwards. Further, the axillary nerve passes behind the lateral humerus before splitting into the posterior and anterior branches supplying part of the deltoid muscle. The cutaneous nerve, which innervates the skin above the lateral surface of the deltoid muscle, belongs to the posterior branch. Consider the axillary nerve in more detail. His anatomy is unique.
Nerve damage
Most often, axillary nerve damage occurs with a fracture of the humerus or shoulder dislocation. In some cases, only the axillary nerve is affected during idiopathic plexopathy of the brachial plexus . What threatens axillary nerve damage? We will understand in this article.
The main clinical manifestation of compression of the axillary nerve is a violation of the shoulder abduction function due to weakness of the deltoid muscle. The periosteal muscle begins to deflect the arm , and therefore the patient can maintain a limited ability to deflect the arm. And although the small round muscle may be weak, this is not always noticeable on clinical examination as a result of the normal functioning of the hypodermic muscle.
The diagnosis can be confirmed only by revealing the weakness of the deltoid muscle and pathological indicators of EMG, which relate to the small round and deltoid muscles. The axillary nerve SPEC during superficial recordings from the muscle (deltoid) serves as a means of detecting potential delay or decreased amplitude of the axillary nerve.
Neuropathy of the upper limb is a fairly common disease in the work of a neurologist. It can be damaged as one axillary nerve, or several nerves at once, and therefore the clinical picture of the disease will differ. Regardless of the causes of the disease, the patient begins to feel pain, loss of sensation, discomfort and other characteristic symptoms.
Causes
Often, patients who have experienced neuropathy of the upper extremities believe that their problems are associated with lack of sleep and fatigue, which can be restored with the help of appropriate rest. Many causes can lead to polyneuropathy of the hands. The most common are:
- Tumor diseases - and tumors are not necessarily located in the shoulder and armpit. Localization can be any.
- Earlier operations (at the surgical site, the blood ceases to circulate normally over time, and this, in turn, promotes muscle atrophy and the formation of edema, including compression of the nerve bundles, which leads to neuropathy).
- Long-term 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 result, neuropathy occurs.
- Various infections, for example, tuberculosis, flu, diphtheria, HIV, herpes, malaria and others.
- Regular hypothermia - the body is very harmful to lower temperatures and stay in this state for a long time.
- The lack 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, including diabetes.
How exactly does a damaged axillary nerve manifest itself?
Symptoms
Symptoms can be divided into concomitant and main. With the manifestation of the main symptoms, a person feels burning pain that haunts him throughout the day, as well as a feeling of numbness of the fingers, hands as a whole and hands. With concomitant symptoms manifested:
- difficulty moving hands;
- swelling;
- impaired coordination of movements;
- involuntary muscle contractions, cramps, cramps;
- decrease in temperature sensitivity;
- unpleasant sensations of goosebumps.
Damaged Axillary Nerve: Diagnosis
In order to choose the appropriate treatment method, it is very important to conduct a full examination of the patient, do tests, take special tests, evaluate reflexes and muscle strength. Instrumental diagnostic methods include: magnetic tomography, electroneuromyography.
These methods can detect nerve damage, identify the cause and extent of conduction disturbances. If necessary, the specialist can refer the patient for additional tests to exclude another pathology. And only after receiving the results can a diagnosis be made. Very informative axillary nerve topography.
Neuropathy
The axillary neuropathy is accompanied by a limitation (impossibility) of shoulder abduction, its movement back and forth, impaired sensitivity of the innervation zone, and atrophy of the deltoid muscle. Compression of the quadrilateral opening - Tunnel syndrome of the axillary nerve (triceps, major and minor round muscles, humerus). The pain is localized in the shoulder region and increases with rotation and shoulder abduction. Differentiation should be carried out from discogenic cervical radiculitis and shoulder-shoulder periarthrosis.
Neuritis
Neuritis is a disease of the peripheral nerve (facial, intercostal, occipital, nerves of the extremities), which is inflammatory in nature and manifests itself in pain along the nerve, muscle weakness of the innervated area, and a violation of sensitivity. When several nerves are affected, the disease is called polyneuritis. The projection of the axillary nerve plays an important role here.
The functions of the nerve, the area of innervation and the degree of damage determine the clinical picture of neuritis. In most cases, the peripheral nerves are composed of various types of nerve fibers: autonomic, sensory, motor. Any type of neuritis is characterized by symptoms caused by damage to each type of fiber:
- trophic and autonomic disorders cause the appearance of trophic ulcers, swelling, brittle nails, blueness of the skin, dryness and thinning of the skin, depigmentation and local hair loss, sweating, etc.
- sensitivity disorders cause loss or decrease in sensitivity of the innervation zone, paresthesia (sensation of goosebumps, tingling), numbness;
- violation of the activity of movements causes loss or decrease in tendon reflexes, paresis (partial) or paralysis (complete) decrease in the strength of innervated muscles, atrophy.
First signs
Basically, the first signs of nerve damage are numbness and pain. The clinical picture of some types of neuritis shows specific manifestations that are associated with the area that the axillary nerve innervates.
Axillary nerve neuritis 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.
In isolation, the axillary nerve is affected by injury to the brachial plexus or dislocation of the shoulder head. This leads to the loss of raising a hand to a horizontal level.
In a small strip of skin along the posterior surface of the upper part of the shoulder, sensitivity is impaired. In some cases, there is an injury to the lateral cutaneous nerve of the forearm and violation of this sensitivity on the outer back, radial side of the forearm. All these are the nerves of the axillary region.
To quickly navigate the damage to the nerves of the upper extremities, especially the ulnar, median and radial, it will be quite enough to examine the patient for some typical movements of the fingers, hands and forearm. But first you need to make sure that there are no mechanical obstacles to movement due to the development of ankylosis or contractures. When the patient will perform the necessary movements, the specialist will need to make sure that the strength and volume of these movements are intact.
Muscle groups
The following muscle group is included in the motor innervation of the axillary (axillary) nerve:
Deltoid muscle C5-C6:
- During contraction of the back, the raised shoulder pulls back.
- During the contraction of the middle part, the shoulder is retracted to a horizontal plane.
- During contraction of the front, the raised limb is pulled forward.
Small circular muscle C4-C5, contributing to the rotation of the shoulder outward.
Test
To determine the strength of the deltoid muscle, you can conduct the following test: while sitting or standing, the patient raises his arm to a horizontal level, and the doctor at this time resists this movement by palpating the contracted muscle.
When an axillary nerve is damaged, the following occurs:
- Sensitivity is impaired on the shoulder surface (upper outer).
- Axillary nerve palsy, atrophy of the deltoid muscle.
The symptom of a dovetail is that extension of a sore arm is much less than healthy. And if you look at the patient from the side, you get the impression of a split swallow tail and lag in shoulder extension.