The supraclavicular nerve is located in the plexus of the neck and corresponds to several sensitive nerve branches. The nerve innervates various portions of the skin in the neck–chest-shoulder region. Failure of the supraclavicular nerve results in sensory disturbances.
What is the supraclavicular nerve?
The cervical plexus is also known as the cervical plexus. This is a plexus of nerves made up of the anterior rami of the spinal nerves in segments C1 to C4. The individual nerve rami of the cervical plexus penetrate between the scalenus anterior and scalenus medius muscles down into the deeper neck region. The plexus innervates the ventral cervical muscles motorically. The same is true for the infrahyal muscles of the inferior hyoid and for the diaphragm. Sensory branches also articulate in the cervical plexus. They innervate the ear, neck, skin of the clavicle, and shoulder. The supraclavicular nerves form part of the sensitive nerves that meet in the cervical plexus. They are also called supraclavicular nerves and correspond to a multimembered group of sensitive nerve branches originating in the cervical plexus. The root cells of the nerve group are located within the spinal ganglia of third and fourth cervical segments in the spinal cord, that is, in C3 and C4. The individual nerve branches are divided into nervi supraclaviculares anteriores, intermedii and posteriores, i.e., anterior, middle and posterior supraclavicular nerves. Together, they control the sensitivity of the supraclavicular region, i.e., that of the skin in the upper chest, shoulder, and lower neck regions.
Anatomy and structure
The supraclavicular nerves originate from the anterior branches of the second and third spinal nerves. After their isolation from the cervical plexus, the supraclavicular nerves pierce the cervical muscles at the so-called Erb’s point, from where they descend along the neck into the subcutis. The nervi supraclaviculares anteriores cross over vena jugularis externa and musculus sternocleidomastoideus. The nervi supraclaviculares intermedii cross over the clavicle, and the nervi supraclaviculares posteriores extend obliquely over the trapezius muscle and the bony corner on the scapula. At Erb’s point, all supraclavicular nerves meet the lesser occipital nerve, transverse collateral nerve, and auricular magnus nerve. Near the clavicle, the nerves become cutaneous branches as they pierce the platysma next to the superficial cervical fascia. In terms of their direction of conduction, the nerves are afferent nerves. This means that they lead toward the central nervous system. Unlike motor nerves, which always contain portions of sensory nerves, sensory nerves such as the supraclavicular nerve are considered to be purely sensory. Thus, they do not contain any motor fibers. A myelin layer around the nerves serves as insulation.
Function and tasks
The supraclavicular nerve or, better, the supraclavicular nerves are sensitive nerves connected to receptors. Such receptors are sensory cells that register temperature, pain, and touch stimuli such as pressure. Incoming stimuli are converted by the receptors into bioelectrical excitation, depending on the intensity of the stimulus, and thus into the language of the central nervous system. Afferent sensory nerves ensure that the stimuli from the receptors arrive as action potentials in the central nervous system, where they are processed further and can enter consciousness. The nervi supraclaviculares anteriores connect the skin in the anterior and inferior cervical region and the upper thoracic region up to the midline with the central nervous system. Accordingly, they conduct all temperature, pain and touch stimuli from this region via the spinal cord to the brain. The nervi supraclaviculares intermedii or nervi supraclaviculares medii communicate with the sensitive cutaneous branches of intercostal nerves and transmit temperature, pain and touch stimuli from the skin over the deltoid and greater pectoral muscle ascending. The nervi supraclaviculares laterales or nervi supraclaviculares posteriores transmit the same stimuli from the skin in the upper shoulder region to the spinal cord and brain. Thus, the nerves together are responsible for the sensitivity of different skin regions in the neck-shoulder-chest area. Through their myelin layer, the nerves are protected against loss of excitation like a plastic-coated cable.
Diseases
Damage to the supraclavicular nerve causes disturbances in sensitivity in the skin regions mentioned. If the nerve fails completely, outright numbness may occur. In this case, the numbness is often associated with a foreign body sensation. In cases of only limited dysfunction of the sensitive nerves, tingling sensations usually occur. In some cases, only the differentiation of cold and hot stimuli on the skin is disturbed. An isolated pain sensation disorder is also conceivable, but relatively rare. In most cases, partial nerve failure is related to nerve compression. In this context, an isolated interruption of the described conduction pathways in the cervical plexus occurs only rarely. More frequently, there is entrapment of the entire plexus, so especially in anatomic bottlenecks between the external jugular vein and the sternocleidomastoid muscle. Nerve compression syndromes of this type can be caused by accidents. Hyperplasia and an associated increase in the size of the sternocleidomastoid muscle due to excessive stress may also cause the compression. In rare cases, sensory disturbance due to conduction disturbance of the supraclavicular nerves is also due to a tumor. Far more frequently, nerve inflammation is the trigger. Often, these are peripheral nerve inflammations, in which the myelin around the nerves degrades and thus promotes loss of excitation of the affected conduction. Peripheral demyelination often occurs in the context of malnutrition, poisoning, infection, or after trauma. When inflammation in the associated segment of the spinal cord causes the supraclavicular nerves to fail, it is usually either bacterial or autoimmunologic.
