Describe the anatomy and physiology relevant to spinal anaesthesia, including vertebral landmarks, meningeal layers, spinal cord termination, and cerebrospinal fluid (CSF) dynamics. Explain the pharmacology of local anaesthetic agents used intrathecally, including bupivacaine, ropivacaine, lidocaine, prilocaine, and common adjuvants. Discuss the principles of baricity and factors influencing the spread of spinal anaesthesia, and apply them to clinical practice. Identify the indications and contraindications for spinal anaesthesia across surgical, obstetric, urological, and lower limb procedures. Demonstrate knowledge of safe preparation and performance of spinal anaesthesia, including patient positioning, needle selection, aseptic technique, and spinal needle insertion approaches. Assess the adequacy of sensory and motor blockade using appropriate clinical methods and dermatome assessment. Recognize and manage the physiological effects and complications of spinal anaesthesia, including hypotension, bradycardia, high spinal block, post-dural puncture headache, neurological complications, and urinary retention. Identify causes of incomplete or failed spinal blocks and implement rescue strategies, including patient repositioning, low-dose ketamine rescue, and conversion to general anaesthesia when indicated. Apply evidence-based guidelines and safety principles from recognized anaesthesia organizations such as ASA, ASRA, and NYSORA in the practice of spinal anaesthesia.