The supraclavicular nerve is a branch of the cervical plexus, specifically arising from the third and fourth cervical spinal nerves (C3, C4). It plays a crucial role in providing sensation to certain regions of the body.
Location
The supraclavicular nerve emerges from the cervical plexus and travels downward, passing behind the sternocleidomastoid muscle. It then spreads out over the clavicle (collarbone), dividing into three distinct branches: medial, intermediate, and lateral. These branches extend over the upper chest and shoulder area, providing sensory innervation to the skin over the clavicle, upper chest, and shoulder region.
Structure and Anatomy
The supraclavicular nerve is a sensory nerve that arises from the cervical plexus and is divided into several branches, each with distinct anatomical pathways. Below is a detailed explanation of its anatomy.
Origin
The supraclavicular nerve originates from the cervical plexus, specifically from the ventral rami of the third and fourth cervical spinal nerves (C3 and C4). The cervical plexus is a network of nerves located in the neck, which supplies sensory and motor innervation to various parts of the head, neck, and upper chest.
Pathway
After originating from the cervical plexus, the supraclavicular nerve travels inferiorly, passing posterior to the sternocleidomastoid muscle. As it descends, the nerve courses toward the clavicle, running deep to the platysma muscle.
Branches
Once the supraclavicular nerve reaches the region of the clavicle, it divides into three main branches:
- Medial Supraclavicular Nerve:This branch passes medially and inferiorly, crossing over the clavicle to innervate the skin over the sternoclavicular joint and the upper portion of the chest, near the midline.
- Intermediate Supraclavicular Nerve:The intermediate branch travels more laterally than the medial branch, passing over the clavicle to supply the skin over the pectoral region.
- Lateral Supraclavicular Nerve:The lateral branch extends toward the shoulder, traveling across the acromion and trapezius muscle to innervate the skin over the lateral aspect of the shoulder and upper chest.
Relations
As the supraclavicular nerve descends, it has close anatomical relations with several important structures:
- Sternocleidomastoid muscle: The nerve travels posterior to this muscle as it exits the cervical plexus.
- Platysma muscle: The nerve passes deep to this thin muscle located within the superficial fascia of the neck.
- Clavicle: The nerve branches pass over the clavicle to reach the skin of the upper chest and shoulder.
- Trapezius muscle: The lateral branch of the supraclavicular nerve passes near or over the trapezius muscle as it travels toward the acromion.
Distribution
Each branch of the supraclavicular nerve spreads out to cover a distinct region of the skin:
- Medial Branch: Innervates the skin over the sternoclavicular joint and the upper chest near the sternum.
- Intermediate Branch: Supplies the skin over the middle portion of the upper chest, above the pectoral muscles.
- Lateral Branch: Provides sensory innervation to the skin over the shoulder and upper lateral chest, extending as far as the acromion.
Termination
The supraclavicular nerve branches terminate as superficial cutaneous nerves, innervating the skin in their respective regions. These branches do not have deep or muscular innervation, as their primary role is sensory in nature.
Function
The supraclavicular nerve plays a key sensory role, as it is responsible for transmitting sensory information from certain areas of the skin to the central nervous system. Below is a detailed description of its functions:
Sensory Innervation
The primary function of the supraclavicular nerve is sensory innervation. It does not have any motor functions and solely transmits sensory stimuli from the skin to the spinal cord and brain. The nerve supplies sensory input from the skin in the following regions:
- Clavicular Region:The supraclavicular nerve is responsible for providing sensory innervation to the skin over the clavicle. This allows the brain to perceive tactile sensations, temperature changes, pain, and pressure in the skin overlying the collarbone.
- Shoulder and Upper Chest:The lateral branch of the supraclavicular nerve innervates the skin over the acromion and upper lateral chest area. This allows for sensory perception on the top and lateral portions of the shoulder. This is important for detecting contact with clothing, temperature variations, and potential injuries.
- Anterior Thoracic Wall:The intermediate and medial branches supply the skin over the upper anterior chest, particularly above the pectoral muscles. These branches allow the detection of sensations over the upper chest, including the sternoclavicular joint.
Role in Sensory Transmission
The supraclavicular nerve transmits signals from specialized sensory receptors in the skin. These signals are sent to the cervical plexus and then relayed to the central nervous system. The types of sensory signals include:
- Tactile Sensation: The ability to feel touch, such as light pressure or more intense contact with objects.
- Temperature Sensation: The detection of warmth or cold on the skin in its innervation regions.
- Pain Sensation: The ability to sense pain, which serves as a warning system for potential tissue damage or injury.
- Proprioception: Though limited, the nerve may play a minor role in proprioception, or the awareness of body positioning, specifically in the shoulder and clavicle area.
Dermatome Coverage
The supraclavicular nerve contributes to the dermatome pattern associated with the C3 and C4 cervical nerves. Dermatomes are regions of skin innervated by specific spinal nerve roots, and the supraclavicular nerve covers the region that corresponds to the C3-C4 dermatome, which includes parts of the neck, shoulder, and upper chest.
Clinical Significance
The supraclavicular nerve is clinically significant due to its superficial location, making it susceptible to injury during trauma, surgical procedures, or certain medical conditions. Here are some key aspects of its clinical importance:
- Nerve Block: The supraclavicular nerve is often targeted for regional anesthesia, particularly during surgeries involving the shoulder, clavicle, or upper chest. A supraclavicular nerve block can provide effective pain relief or anesthesia for these regions.
- Injury and Trauma: Due to its superficial course over the clavicle, the supraclavicular nerve is vulnerable to injury in cases of trauma, fractures of the clavicle, or blunt force to the shoulder area. Damage to the nerve can lead to sensory loss or numbness in the regions it innervates.
- Post-Surgical Complications: Procedures such as clavicle surgery, cervical lymph node excision, or shoulder operations may accidentally damage the supraclavicular nerve. This can result in postoperative numbness or paresthesia (tingling) over the chest and shoulder.
- Neuralgia: Irritation or compression of the supraclavicular nerve may lead to supraclavicular neuralgia, which manifests as pain radiating from the neck to the shoulder and upper chest. This condition can occur due to nerve entrapment or inflammation.
