AnSo is a convenient resource designed to help anaesthetists identify common sonoanatomy, in a time efficient manner, within the busy operating theatre. It has been created by practicing anaesthetists with an interest in teaching ultrasound and regional anaesthesia. AnSo helps identify not only the target structures but all the surrounding sonoanatomy. This more comprehensive understanding of the sonoanatomy helps detect anatomical variability, improves the safety and efficacy of procedures, and facilitates learning and teaching. AnSo also: - provides multiple examples of the sonoanatomy as every individual is different, - provides landmark sketches useful for developing pattern recognition of landmark structures, and for trainees to draw in exams, - displays the cutaneous, motor, osseous and visceral innervation of the numerous nerve blocks and fascial plane blocks now available, facilitating appropriate block choice and knowledge of expected results, - allows combining and comparing block innervation, - allows images to be flipped to display both L and R sided orientation, - demonstrates functional ergonomics with patient, ultrasound screen and proceduralist positioning essential for efficient practical performance, - provides block notes with sonoanatomy tips and practical tips from experienced clinicians which can be invaluable to the learner. AnSo is not only for regional anaesthesia but includes many other perioperative uses of ultrasound relevant to the anaesthetist, such as: - airway - gastric antrum - vascular access - spine - transthoracic echo - lung signs AnSo has been designed in a format that can be easily updated and distributed to users so the information can be kept as current as possible in this rapidly expanding field. AnSo contains: - over 250 ultrasound images with over 1500 sonoanatomy colour overlays, - innervation images, - ergonomic images, - landmarks pattern sketches, - loops when required for dynamic sonoanatomy, - notes with tips from experienced clinicians. AnSo does not require an internet connection to run. Once downloaded all data is stored on your device so it will work anywhere and images will display without any delay. It can be useful both in and out of theatre, when performing procedures, and when learning or teaching ultrasound. There is no advertising on the app. Download AnSo today and always have access to this sonoanatomy and nerve block resource.