Prospective Observational Study of Anatomical Correlation between External Jugular Vein and Brachial Plexus at Cricoid and Supraclavicular Levels Using Ultrasonography

Background: Regional anaesthesia is widely used for upper limb surgeries. Although ultrasound guidance is considered the gold standard for brachial plexus blocks, its availability is limited in many developing countries. Reliable surface anatomical landmarks therefore remain clinically important. Aim: To evaluate the anatomical relationship between the external jugular vein (EJV) and the brachial plexus (BP) at the cricoid and supraclavicular levels using ultrasonography, and to assess the usefulness of EJV as a surface landmark for landmark-guided brachial plexus block. Methods: This prospective observational study included 270 ASA physical status I and II adults aged 18–60 years. Ultrasound was used to identify the position of the brachial plexus relative to the external jugular vein at the cricoid and supraclavicular levels. Distances from skin to brachial plexus and from EJV to brachial plexus were measured and analysed statistically. Results: In 90% of patients, the brachial plexus was located medial to the external jugular vein at both levels. At the cricoid level, the EJV-to-brachial plexus distance was less than 1 cm in 92.2% of cases. A strong positive correlation was observed between skin-to-brachial plexus distance at the two levels (r = 0.75), while EJV-tobrachial plexus distance showed no significant correlation (r = −0.02). Conclusion: The external jugular vein shows a consistent anatomical relationship with the brachial plexus and may serve as a useful surface landmark for landmark-guided brachial plexus block, particularly in resourcelimited settings where ultrasound is unavailable.