Symptoms of lesions of the cervical plexus and its branches

For precise and differentiated control of head movements, the numerous muscles of the neck require separate innervation. Therefore, a significant portion of the fibers from the spinal roots and nerves, without intertwining, pass directly to the muscles or skin of the neck and head.

The first cervical nerve (n. cervicalis primus) exits the spinal canal through the gap between the occipital bone and the atlas along the sulcus a. vertebralis and divides into anterior and posterior branches.

The anterior branch of the CI emerges on the anterolateral surface of the spine between the lateral rectus capitis and the anterior rectus capitis and innervates them. Contraction of the lateral rectus capitis on one side causes the head to tilt to the same side, while contraction on both sides causes the head to tilt forward. The anterior rectus capitis tilts the head to its side.

The posterior branch of the CI is called the suboccipital nerve (n. suboccipitalis) and supplies the large posterior and small posterior rectus capitis muscles, the superior and inferior oblique capitis muscles. When contracted unilaterally, all these muscles tilt the head back and to the side, and when contracted bilaterally, backwards.

Isolated damage to the first cervical spinal nerve is rare and is observed in pathological conditions in the upper cervical vertebrae. When the fibers of this nerve are irritated, convulsive contractions of the lower oblique muscle of the head occur. With a unilateral clonic spasm of this muscle, the head rhythmically turns to the affected side; with a tonic spasm, the head turns slowly and this turn is longer. In the case of a bilateral spasm, the head turns first to one side, then to the other - a rotational spasm (tic rotatore).

The second cervical nerve (n. cervicalis secundus), emerging from the intervertebral foramen CII, divides into anterior and posterior branches. The anterior branch participates in the formation of the cervical plexus. The posterior branch passes posteriorly between the atlas and the axis vertebra, bends around the lower edge of the inferior oblique muscle of the head and divides into three main branches: ascending, descending and the greater occipital nerve (n. occipitalis major). Two branches innervate part of the inferior oblique muscle of the head and the splenius muscle. With unilateral contraction of these muscles, the head rotates in the corresponding direction, with bilateral contraction, the head tilts back with extension of the neck.

A test to determine the strength of the posterior group of head muscles: the patient is asked to tilt his head back, the examiner resists this movement.

The greater occipital nerve emerges from under the lower edge of the inferior oblique muscle of the head and is directed upward in an arc. Together with the occipital artery, this nerve pierces the tendon of the trapezius muscle near the external occipital protuberance, penetrates under the skin and innervates the skin of the occipital and parietal regions. When this nerve is damaged (flu, spondyloarthritis, injuries, tumors, reflex spasm of the inferior oblique muscle of the head), sharp pain appears in the back of the head. The pain is paroxysmal and intensifies with sudden movements of the head. Patients hold their head still, slightly tilting it back or to the side. In neuralgia of the greater occipital nerve, the pain point is localized on the inner third of the line connecting the mastoid process and the external occipital protuberance (the exit point of this nerve). Hypo- or hyperesthesia in the occipital region and hair loss are sometimes noted.

Cervical plexus (plexus cervicalis). It is formed by the anterior branches of the CI - CIV spinal nerves and is located lateral to the transverse processes on the anterior surface of the middle scalene muscle and the muscle that raises the scapula; it is covered in front by the sternocleidomastoid muscle. Sensory, motor and mixed nerves branch off from the plexus. Along the course of these nerves, there are areas of perforation through the fascia or the muscle itself, where conditions for compression-ischemic lesions of the nerve trunk can be created.

The lesser occipital nerve (n. occipitalis minor) branches off from the cervical plexus and consists of fibers of spinal nerves CI – CIII. It passes through the fascial sheath of the superior oblique muscle of the head and branches in the skin of the outer part of the occipital region. The clinical picture of the lesion is represented by complaints of paresthesia (numbness, tingling, crawling) in the outer occipital region. They occur at night and after sleep. Hypoesthesia is revealed in the branching zone of the lesser occipital nerve and pain upon palpation of the point at the posterior edge of the sternocleidomastoid muscle at the site of its attachment to the mastoid process.

Similar sensations may occur in the temporo-occipital region, auricle and external auditory canal. In such cases, differential diagnostics is performed with damage to the large auricular nerve, which consists of fibers of the CIII spinal nerve. If paresthesia and pain are localized along the outer surface of the neck from the chin to the collarbone, one can think of damage to the transverse nerve of the neck (n. transversus colli) - a branch of the CII - CIII spinal nerves.

The supraclavicular nerves (nn. supraclavicularis) are formed from the anterior branches of the CIII and CIV spinal nerves. They emerge from under the posterior edge of the sternocleidomastoid muscle and run obliquely downwards into the supraclavicular fossa. Here they are divided into three groups:

• the anterior supraclavicular nerves branch in the skin above the sternal portion of the clavicle;
• the middle supraclavicular nerves cross the clavicle and supply the skin from the chest area to the fourth rib;
• The posterior supraclavicular nerves run along the outer edge of the trapezius muscle and end in the skin of the upper scapular region above the deltoid muscle.

Damage to these nerves is accompanied by pain in the neck area, which intensifies when tilting the head to the sides. With intense pain, tonic tension of the occipital muscles is possible, which leads to a forced position of the head (tilted to the side and fixed motionless). In such cases, it is necessary to differentiate from the meningeal symptom (rigidity of the occipital muscles). Disorders of superficial sensitivity (hyperesthesia, hypo- or anesthesia) are observed. Pain points are detected by pressure on the posterior edge of the sternocleidomastoid muscle.

The muscular branches of the cervical plexus innervate: the intertransverse muscles, which, with unilateral contraction, participate in tilting the neck to the side (innervated by the CI - CII segment); the long capitis muscle - tilts the cervical spine and head forward (innervated by the CI-CII segment); the inferior hyoid muscles (mm. omohyoideus, stenohyoideus, sternothyroideus), which pull the hyoid bone during swallowing (innervated by the CI - CII segment); the sternocleidomastoid muscle - with unilateral contraction tilts the head in the direction of contraction, and the face turns in the opposite direction; with bilateral contraction - the head is thrown back (innervated by the CII -CIII segment and n. accessorius).

Tests to determine the strength of the sternocleidomastoid muscle:

1. the subject is asked to tilt his head to the side and turn his face in the direction opposite to the tilt of the head; the examiner resists this movement;
2. The patient is asked to tilt the head back; the examiner resists this movement and palpates the contracted muscle.

The muscular branches of the cervical plexus also innervate the trapezius muscle, which brings the scapula closer to the spine if the entire muscle contracts, raises the scapula when the upper bundles contract, and lowers the scapula when the lower portion contracts (innervated by the CII - CIV segment, n. accessorius).

Test for determining the strength of the upper trapezius muscle: the subject is asked to shrug his shoulders; the examiner resists this movement. When the upper part of m. trapezii contracts, the scapula rises upward and its lower angle rotates outward. When this muscle is paralyzed, the shoulder drops, the lower angle of the scapula rotates medially.

Test for determining the strength of the middle part of the trapezius muscle: the subject is asked to move the shoulder backwards, the examiner resists this movement and palpates the contracted part of the muscle. Normally, when the middle part of m. trapezii acts, the scapula is brought to the spinal column; in paralysis, the scapula is abducted and slightly behind the chest.

Test for determining the weakness of the lower part of the trapezius muscle: the subject is asked to move the raised upper limb backwards, the examiner resists this movement and palpates the contracted lower part of the muscle. Normally, the scapula is slightly lowered and approaches the spinal column. When this muscle is paralyzed, the scapula is slightly raised and separated from the spinal column.

The phrenic nerve (n. phrenicus) is a mixed nerve of the cervical plexus - it consists of fibers of the CIII-CV spinal nerves, as well as sympathetic fibers from the middle and lower cervical ganglia of the sympathetic trunk. The nerve is located along the anterior scalene muscle downwards and penetrates the thoracic cavity, passing between the subclavian artery and vein. The left phrenic nerve goes along the anterior surface of the aortic arch, in front of the root of the left lung and along the left lateral surface of the pericardium to the diaphragm. The right one is located in front of the root of the right lung and passes along the lateral surface of the pericardium to the diaphragm. The motor fibers of the nerve supply the diaphragm, the sensory fibers innervate the pleura, pericardium, liver and its ligaments, and partially the peritoneum. This nerve anastomoses with the celiac plexus and the sympathetic plexus of the diaphragm.

When contracting, the dome of the diaphragm flattens, which increases the volume of the chest and facilitates the act of inhalation.

Test for determining the action of the diaphragm: the subject is asked to take a deep breath in a supine position, the examiner palpates the tense abdominal wall. In case of unilateral paralysis of the diaphragm, a weakening of the tension of the corresponding half of the abdominal wall is noted.

Diaphragmatic paralysis leads to limited mobility of the lungs and some respiratory distress. When inhaling, the diaphragm is passively raised by the muscles of the anterior abdominal wall. The type of respiratory movements becomes paradoxical: when inhaling, the epigastric region sinks in, and when exhaling, it protrudes (normally, the opposite); coughing movements are difficult. The mobility of the diaphragm is well assessed by X-ray examination.

When the phrenic nerve is irritated, a spasm of the diaphragm occurs, which manifests itself as hiccups, pain spreading to the shoulder girdle, shoulder joint, neck and chest.

The phrenic nerve is affected by infectious diseases (diphtheria, scarlet fever, flu), intoxication, trauma, metastases of malignant tumors in the cervical vertebrae, etc.

Simultaneous damage to the entire cervical plexus is rare (in case of infection, intoxication, trauma, tumor). In case of bilateral paralysis of the neck muscles, the head tilts forward, the patient cannot raise it. Irritation of the trunks of the cervical plexus leads to a spasm that spreads to the oblique muscles of the head, the splenius muscle of the neck and the diaphragm. In case of a tonic spasm of the splenius muscle of the neck, the head tilts back and to the affected side, in case of bilateral spasm, it is thrown back, which creates the impression of rigidity of the muscles of the back of the head.

Neuralgic syndrome of cervical plexus damage is expressed by pain in the occipital region, posterolateral surface of the neck and in the earlobe. Sensitivity disorders are possible in this area.

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