Anatomy, Imaging, and Clinical Significance of the Cervicothoracic (Stellate) Ganglion.

Background/Objectives: The stellate ganglion (SG), formed by the fusion of the inferior cervical and first thoracic sympathetic ganglia in approximately 80% of individuals, plays crucial roles in cardiac innervation, pain management, and autonomic regulation. This review examines the anatomical variations, histological structure, clinical applications, and therapeutic implications of the SG and stellate ganglion block (SGB), presenting original high-resolution magnetic resonance imaging (MRI) evidence of SG visualization, an underutilized approach in autonomic nervous system research. Methods: We conducted a comprehensive literature review of anatomical, physiological, and clinical studies on the SG, incorporating original anatomical dissections and high-resolution MRI. Contemporary research on SGB applications, complications, and mechanisms of action was analysed and correlated with imaging characteristics. Results: The SG demonstrates significant anatomical variability, including the presence of intermediate ganglia, accessory nerve pathways, and variable relationships with surrounding vascular structures. Our original MRI imaging consistently identified the SG at the thoracic inlet, anterior to the neck of the first rib, lateral to the longus colli muscle, and posterior to the vertebral artery, demonstrating that advanced imaging can reliably visualize this critical autonomic structure and its anatomical variants. Histologically, it contains typical sympathetic architecture, comprising postganglionic neurons, satellite glial cells, and specialized SIF cells that modulate ganglionic transmission. SGB shows therapeutic efficacy across diverse conditions, including cardiac arrhythmias, chronic pain syndromes, post-traumatic stress disorder, sleep disorders, and immune dysfunction. The procedure's mechanisms involve both direct sympathetic blockade and complex neuroimmune pathways that affect central autonomic centers and lymphoid organs. Complications include vascular injury, pneumothorax, and nerve blocks affecting the recurrent laryngeal and phrenic nerves. Conclusions: The SG represents a critical autonomic structure with expanding clinical applications. This work advances the field by demonstrating that high-resolution MRI can consistently and non-invasively visualize the SG and its anatomical variations, knowledge previously mostly limited to cadaveric studies. Understanding these imaging-defined anatomical variations is essential for optimizing therapeutic interventions. Advanced imaging guidance integrated with comprehensive anatomical knowledge is crucial for maximizing efficacy while minimizing complications in stellate ganglion block procedures.