The axillary nerve and radial are the components of the posterior trunk of the brachial plexus. A nerve passes under the shoulder joint, giving a branch that innervates the small round muscle, which rotates the arm outward. The axillary nerve then passes behind the lateral humerus before splitting into posterior and anterior branches supplying part of the deltoid muscle. The posterior branch is the cutaneous nerve, which innervates the skin above the lateral surface of the deltoid muscle. Let's take a closer look at the axillary nerve. Its anatomy is unique.
Nerve damage
Most often, damage to the axillary nerve occurs with a fracture of the humerus or dislocation of the shoulder. In some cases, only the axillary nerve is affected during idiopathic brachial plexus plexopathy. What threatens damage to the axillary nerve? Let's figure it out in this article.
The main clinical manifestation of axillary nerve compression is impaired shoulder abduction function due to weakness of the deltoid muscle. The periosteal muscle begins to abduct the arm, and therefore the patient can maintain a limitedthe ability to withdraw the hand. Although the teres minor may be weak, this is not always apparent on clinical examination as a result of normal subosseous function.
Diagnosis can only be confirmed by detecting weakness of the deltoid muscle and abnormal EMG readings that relate to the teres minor and deltoid muscles. SNV of the axillary nerve when performing surface recordings from the muscle (deltoid) serves as a means of detecting potential delay or reduced amplitude of IVD of the axillary nerve.
Neuropathy of the upper limb – is a fairly common disease in the work of a neurologist. Both one axillary nerve and several nerves at once can be damaged, and therefore the clinical picture of the disease will also differ. Regardless of the causes of the disease, the patient begins to feel pain, loss of sensation, discomfort and other characteristic symptoms.
Reasons
Often, patients with upper extremity neuropathy believe that their problems are due to lack of sleep and fatigue, which can be restored with appropriate rest. Many causes can lead to hand polyneuropathy. The most common are:
- Tumor diseases - and tumors are not necessarily located in the shoulder and armpit. Localization can be any.
- Previous operations (at the surgical site, blood stops circulating over timenormal, and this, in turn, contributes to muscle atrophy and the formation of 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 extremities with subsequent development of edema that compresses the nerve - as a result, neuropathy occurs.
- Miscellaneous past infections, such as tuberculosis, influenza, diphtheria, HIV, herpes, malaria and others.
- Regular hypothermia - it is very harmful for the body to lower temperatures and stay in this state for a long time.
- Lack of certain groups of vitamins in the body, often vitamin B.
- Irradiation - affects the body extremely negatively.
- Intoxication of the body.
- Excessive and intense exercise on the muscles.
- Endocrine diseases, including diabetes.
How exactly does a damaged axillary nerve manifest itself?
Symptoms
Symptomatology can be divided into concomitant and main. With the manifestation of the main symptoms, a person feels a burning pain that haunts him throughout the day, as well as a feeling of numbness of the fingers, hands as a whole and the hand. With concomitant symptoms, it manifests itself:
- difficulty moving arms;
- puffiness;
- discoordination of movements;
- involuntary muscle contractions, cramps, spasms;
- decrease in temperature sensitivity;
- discomfortgoosebumps.
Injured axillary nerve: diagnosis
To choose the right treatment method, it is very important to conduct a full examination of the patient, do tests, take special samples, evaluate reflexes and muscle strength. Instrumental diagnostic methods include: magnetic tomography, electroneuromyography.
These methods allow you to detect nerve damage, identify the cause and extent of conduction disorders. If necessary, the specialist may refer the patient for additional tests to rule out other pathologies. And only after receiving the results can a diagnosis be made. Topography of the axillary nerve is very informative.
Neuropathy
Neuropathy of the axillary nerve is accompanied by restriction (impossibility) of shoulder abduction, its movement back and forth, impaired sensitivity of the innervation zone, atrophy of the deltoid muscle. Compression of the quadrilateral foramen - tunnel syndrome of the axillary nerve (triceps, large and small round muscles, humerus). The pain is localized in the shoulder region and increases with rotation and abduction of the shoulder. Differentiation should be carried out from discogenic cervical sciatica and humeroscapular 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 as pain along the nerve, muscle weakness of the innervated area, impairedsensitivity. 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, peripheral nerves consist of various types of nerve fibers: autonomic, sensory, motor. Each type of neuritis is characterized by symptoms caused by damage to each type of fiber:
- trophic and vegetative disorders cause the appearance of trophic ulcers, swelling, brittle nails, cyanosis of the skin, dryness and thinning of the skin, depigmentation and local hair loss, sweating, etc.;
- sensitivity disorders cause loss or decrease in the sensitivity of the innervation zone, paresthesia (goosebumps, tingling), numbness;
- violation of movement activity causes loss or decrease in tendon reflexes, paresis (partial) or paralysis (complete) decrease in the strength of innervated muscles, atrophy.
First signs
In general, the first signs of nerve damage are numbness and pain. The clinical picture of some types of neuritis demonstrates specific manifestations that are associated with the area that the axillary nerve innervates.
Axillary neuritis is expressed in the impossibility of raising the arm to the side, increased 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 wheninjury to the brachial plexus or dislocation of the head of the shoulder. This leads to falling out of raising the arm to the horizontal level.
Sensation is disturbed on a small strip of skin along the posterior outer surface of the upper part of the shoulder. In some cases, the lateral cutaneous nerve of the forearm is injured and, at the same time, sensitivity is disturbed on the outer dorsal, radial side of the forearm. These are all axillary nerves.
To quickly orientate in the defeat of the nerves of the upper extremities, especially the ulnar, median and radial, it will be enough to examine the patient with some typical movements of the fingers, hand and forearm. But first, you should make sure that there are no mechanical obstacles to movement due to the development of ankylosis or contractures. When the patient performs the necessary movements, the specialist will need to make sure that the strength and volume of these movements are preserved.
Muscle groups
The following muscle group is included in the motor innervation of the axillary (axillary) nerve:
Deltoid C5-C6:
- During the contraction of the back, the raised shoulder pulls back.
- During the reduction of the middle part, the shoulder is retracted to the horizontal plane.
- During the contraction of the anterior part, the raised limb is pulled forward.
Tissimus teres minor C4-C5, contributing to outward rotation of the shoulder.
Test
To determine the strength of the deltoid muscle, the following test can be performed: sitting or standing, the patient raises his handto a horizontal level, while the doctor at this time resists this movement by palpating the contracted muscle.
When the axillary nerve is damaged, the following happens:
- Sensitivity is disturbed on the surface of the shoulder (upper outer).
- Axillary nerve palsy, deltoid atrophy.
The dovetail symptom is that the extension of the diseased arm is much less than that of the he althy one. And if you look at the patient from the side, you get the impression of a split dovetail and a lag in shoulder extension.
