Different angles and depth in needling the same acupoint may puncture different tissues, produce varied needling sensation and therapeutic effects. To different acupoints, appropriate angle and depth are selected according to the location of the acupoints. Therefore, angle and depth are especially important in the process of needle insertion. Correct angle and depth are helpful in producing desired therapeutic effects and preventing needling accidents.
(1) Angle of Insertion
The angle formed by the needle and the skin surface is usually classified into three kinds (see Fig.112):
Perpendicular insertion: Perpendicular insertion, in which the needle is inserted perpendicularly, means that there is an angle of 90°formed between the needle and the skin surface. This method is applicable to most acupoints on the body.
Oblique insertion: The needle is inserted obliquely to form an angle of approximately 45°between the needle and the skin surface. This method is used for needling the acupoints close to the important viscera or tissues, or the acupoints which are not suitable for perpendicular and deep insertion.
Horizontal insertion: The needle is inserted transversely to form an angle of about 15°between the needle and the skin surface, also known as transverse insertion. This method is applicable to the areas where the muscle is thin.
(2) Depth of Needle Insertion
In clinical treatment, the depth of insertion mostly depends upon the location of the acupoints, the constitution of the patient and the pathological conditions. For example, shallow insertion is applicable to the needling of such areas as the head, face, chest and abdominal region as well as such patients as infants, people with delicate constitution, or the aged. Deep insertion is applicable to the needling of the acupoints located on the limbs, buttocks and abdominal region as well as the young and the middle-aged with strong constitution and heavy body.