It is difficult to overestimate the importance and importance of the cervical plexus. Its branches set in motion part of the respiratory muscles and ensure the support function of the neck muscles. Therefore, in the pathology of the cervical plexus, part of the vital functions may be impaired.
Anatomy
The cervical nerve plexus is a paired complex formed by the anterior branches of the superior cervical spinal nerve roots. Its branches are supplemented with three arcuate loops connecting the roots to each other, forming a plexus.
Some sources combine it with the shoulder, consisting of the lower half of the cervical nerve roots and the two upper chest. These sources mention the cervical-brachial plexus, which consists of the spinal nerves of the cervical segments of the spinal cord, as well as the two upper thoracic spinal nerves.
Topography
Knowing the topography of the cervical plexus helps to understand what pathological conditions lead to dysfunction of its roots. For specialists, this information is valuable because, knowing the projection of the plexus, it is easieravoid negative influence on him during various medical procedures.
The cervical plexus is located at the level of the upper four vertebrae of the cervical region. Being covered from the lateral side and in front by the sternocleidomastoid muscle, it lies on the anterior-lateral side of the group of deep muscles of the neck.
Structure and functions
Because the branches of the cervical plexus contain both afferent and efferent nerve fibers, they perform both sensory and motor functions.
Accordingly, if the structures of the cervical plexus are affected, both of these areas will suffer.
Motor branches
Muscular, or motor, nerves of the cervical plexus, branching in the nearby muscles of the neck, set them in motion; and in addition, they take part in the formation of the so-called cervical loop, consisting of a descending branch of the hypoglossal nerve and nerve fibers coming from the roots of the nerve plexus. Its function is to innervate the muscles located below the hyoid bone.
It should also be mentioned that both the trapezius and sternocleidomastoid muscles are also innervated by nerve fibers extending from the motor roots of the cervical plexus.
Sensitive Department
Sensitive innervation of the cervical plexus is provided by its so-called cutaneous branches, namely the large ear nerve, the small nerve of the occiput, the transverse cervical and supraclavicularnerves.
Prephrenic nerve
This is another branch of the cervical plexus that has an interesting feature: the phrenic nerve contains both motor fibers that branch in the diaphragm and set it in motion, and sensory fibers that provide innervation to the pericardium, pleura and peritoneum.
This nerve is recognized as the most important branch of those that form the cervical plexus, as it goes to the diaphragm, and its defeat inevitably leads to paresis of the diaphragm of varying severity or its paralysis. This condition is clinically manifested by respiratory failure, up to its severe degree.
In some cases, when the cervical plexus is affected, and in particular the phrenic nerve, the pathology is manifested by clonic convulsions in the diaphragm, which externally manifest as hiccups.
Blood supply
The main source of nutrition for the structures of the upper part of the cervical spine are small branches of the vertebral artery, which, originating from the subclavian artery, rises along the spine, entering the cranial cavity and giving off small branches along its entire length to supply the anatomical formations of the cervical spine.
Cervical plexus pathology
Signs of damage to the cervical nerve plexus are manifested in the form of motor, sensory and trophic disorders. The complexity of symptoms is due to the combination in this formation of nerve fibers,having different functions. Violations relate to the organs to which the cervical plexus gives branches for innervation. Its anatomy is such that with the defeat of each of the roots, all three functions suffer.
Possible defeats
- Traumatization, for example, with dislocations or subluxations of the cervical vertebrae, bruises or birth injuries in newborns.
- Compression syndrome during compression by a neoplasm, bone fragments, hematoma or bandage (with incorrectly performed limb immobilization).
- Infectious-inflammatory lesion that the cervical plexus of the spinal nerves can undergo after infections (herpetic infection, influenza infection, tonsillitis, syphilis).
- Toxic etiology of cervical plexitis. This variant of damage is possible with systematic alcohol abuse or in case of heavy metal poisoning.
- Severe hypothermia (hypothermia) can cause inflammation of the nerve trunks.
- Allergic or autoimmune damage, when the aggressive action of the cells of the immune system is mistakenly directed to the body's own nervous tissue.
- Chronic systemic diseases leading to malnutrition of the nerve trunks.
Manifestations
Among the lesions and diseases of the cervical plexus are:
- One-sided.
- Double-sided.
All cases where the cervical plexus and its branches are affected are characterized by motor, sensory andtrophic disorders in the corresponding zone of innervation. Pathology goes through the following stages in its development:
- Neuralgic stage. Manifestations are associated with irritation of the nerve trunks. Typically, an acute onset in the form of a sharp pain in the lower lateral part of the face with irradiation to the auricle and occipital region, as well as intermittent irradiation to the arm up to the fingertips. The localization of the pain syndrome corresponds to the side of the lesion. Soreness increases significantly with active and passive movements; the state of rest may bring some relief, but the pain at rest, and even at night, does not completely disappear. The pain is accompanied by paresthesias, cooling of the skin and a disorder of temperature sensitivity in the zone of innervation of the affected nerve roots.
- Paralytic stage. The stage of paresis and paralysis (depending on the severity of the lesion) is characterized by signs of dysfunction of the cervical nerves that make up the cervical plexus. Due to damage to the phrenic nerve, hiccups are noted and, due to uncoordinated muscle work, difficulties, disturbances in coughing; disorders of voice formation, breathing - up to severe shortness of breath and in severe cases of respiratory disorders, up to respiratory failure. Trophic disorders cause swelling and cyanotic coloration of the skin, a change in their turgor; in addition, sweating is disturbed in the direction of its strengthening. A long duration of the disease can lead to atrophic changes in the muscles of the shoulder girdle, as a result of whichin the future there will be the formation of habitual dislocations of the shoulder joint; or paralysis of the muscles of the neck, the severity of which leads to the loss of the ability of the cervical muscles to perform their functions: the patient's head in severe cases may lean forward so that the chin is adjacent to the sternum. With such deep lesions, active movements with the help of the affected muscles are impossible; such a patient cannot raise his head on his own.
- Recovery stage. At this stage, impaired nerve functions begin to gradually recover. In some cases, recovery is incomplete, with residual phenomena in the form of paresis or paralysis of the peripheral type (flaccid character) and atrophic changes in the muscles (the wording in the diagnosis of residual phenomena in the form of peripheral paresis should indicate the affected nerve root).
Residual effects:
- Flaccid (peripheral) paresis or paralysis of the muscles of the neck and shoulder girdle, habitual dislocations of the shoulder joint and a characteristic head position due to weakness of the cervical muscles.
- Disorder of muscle tone; convulsions and spasms in the muscle groups innervated by the branches of the cervical plexus.
- Sensory disturbances in the form of paresthesia and painful hyperesthesia in the zone of sensitive innervation of the plexus.
- Trophic disorders of the skin and soft tissues in the affected areas.
Anesthesia
Cervical plexus anesthesia allows for surgical interventions on the neck, thyroid gland, blood vessels of the brachiocephalicgroups for injuries, gunshot wounds, oncological diseases.
Because the branches of the cervical plexus are anastomosed anteriorly along the midline of the neck, the sensory roots behind the edge of the sternocleidomastoid muscle should be anesthetized bilaterally. Such anesthesia allows performing, among other things, major interventions on the tissues of the deep layers of the neck (including laryngectomy, removal of oncological neoplasms).
In order to enhance the effect of anesthesia of the branches of the cervical plexus, additional blocking of the superficial nerve branches leading to the frontal surface of the neck is allowed.
To perform all these manipulations, anesthesia is performed with an anterior approach, since the use of a lateral approach (injection of an anesthetic solution into the subdural space) is associated with a high probability of developing quite serious complications, so the lateral approach is not used if possible.
