The stellate ganglion is a cluster of nerve cells found in the neck. It is part of the sympathetic nervous system, which regulates many involuntary bodily functions.
Anatomy and Location
The stellate ganglion, also known as the cervicothoracic ganglion, typically forms from the fusion of two other ganglia: the inferior cervical ganglion and the first thoracic ganglion. This fusion is observed in approximately 80% of individuals. A ganglion, in this context, refers to a grouping of neuron cell bodies located outside the brain and spinal cord, acting as relay points for nerve signals.
This nerve cluster is positioned within the lower neck. It lies anterior to the neck of the first rib and may extend to the level of the seventh cervical vertebra (C7). The stellate ganglion is situated behind the subclavian artery and anterior to the transverse process of the C7 vertebra. It measures about 2.5 cm in length, 1 cm in width, and 0.5 cm in thickness, though its shape can vary, sometimes appearing star-like, which is where “stellate” comes from.
Nerve fibers from the stellate ganglion contribute to the sympathetic innervation of the head, neck, upper limbs, and upper chest. They extend to spinal nerves and form plexuses around blood vessels like the vertebral and subclavian arteries, influencing blood flow.
Physiological Function
The stellate ganglion plays a significant role within the sympathetic nervous system, which governs the body’s involuntary “fight-or-flight” responses. This system prepares the body to react to perceived threats by increasing alertness and mobilizing resources. The stellate ganglion specifically influences these responses in the upper body.
Its activity affects various physiological processes in the head, neck, upper limbs, and upper chest. This includes the regulation of blood flow, controlling sweating, and influencing heart rate and blood pressure in these areas.
By modulating sympathetic nerve signals, the stellate ganglion contributes to the body’s overall homeostatic balance. It helps coordinate bodily functions such as the dilation of blood vessels and the activity of sweat glands.
Clinical Significance
The stellate ganglion is clinically significant due to its involvement in conditions where its activity may be disrupted. Its location and function make it a target for modulating symptoms in certain disorders.
One area of clinical relevance is Complex Regional Pain Syndrome (CRPS), a chronic pain condition often characterized by severe pain, swelling, and changes in skin temperature or color. It is implicated because CRPS involves an abnormal sympathetic nervous system response, and modulating its activity can help alleviate the pain.
The stellate ganglion is also being explored for its potential role in conditions like hot flashes, particularly in menopausal women or breast cancer survivors. While the exact mechanism is still being researched, it is thought to involve the ganglion’s influence on thermoregulation and levels of certain neurotransmitters. This offers a non-hormonal approach for symptom management.
Furthermore, there is growing interest in the stellate ganglion’s connection to Post-Traumatic Stress Disorder (PTSD) and certain symptoms associated with Long COVID. For Long COVID, symptoms like brain fog, fatigue, and dysautonomia may be linked to autonomic nervous system imbalance, which the stellate ganglion can influence. The stellate ganglion is being investigated for its potential to help “reset” the body’s stress response and improve these symptoms.