Spinal anesthesia technology has been widely used in various surgeries and multi-mode analgesia. Spinal ultrasound imaging has been proved to be a reliable tool for evaluating spinal parameters. Ultrasound-guided spinal puncture technology has also been skillfully applied in clinical practice. How to provide perfect nerve block effect for operation, provide good postoperative analgesia, and prevent unnecessary extensive block leading to other complications and related risks has always been the focus of anesthesiologists. Doses and the relationship between the anesthesia plane great individual differences, and previous research on the patient's own condition such as height, weight, 6 to the anesthesia plane have different results, the influence of clinical work often refer patients height adjustment of drug doses, this research attempts to evaluate ultrasound was used to assess spinal vertebral body in the plane of the length and width of subarachnoid and anesthesia.

Inclusion Criteria:

• Patients undergoing elective lower limbs surgery
• ASA: grade I to III

Exclusion Criteria:

• There are contraindications to spinal anesthesia
• Allergic to local anesthetics
• Patient refused

Patients undergoing elective surgery under spinal anesthesia. Inclusion criteria: (1) Elective lower extremity surgery; (3) ASA (American Society of Anesthesiologists) Grading: ⅰ - ⅲ.