The normal human spine consists of 33 vertebrae, including 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, and 9 sacrococcygeal vertebrae, which are interconnected by intervertebral discs as well as adjacent ligaments and small joints, and the 17th vertebra, which is the 10th thoracic vertebra. When looking for body surface markers, the first obvious spinous process felt in the middle of the back when a normal person lowers his head is the spinous process of the 7th cervical vertebra, and the 10th spinous process counted down from this part is the level of the spinous process of the 10th thoracic vertebra, which is the level of the 10th thoracic vertebra. In the case of sitting upright, the back is slightly arched, the two upper limbs are naturally lowered, and the position of the lower corner of the scapula is at the same level as the spinous process of the seventh thoracic vertebra, from which the level of the 10th thoracic vertebra is counted 3 more spinous processes downward. The markings on the body surface can only roughly determine the position of the vertebrae, if you want to pinpoint the position, it is best to do so under x-ray fluoroscopy.