LOCATION
On the lateral end of the transverse crease of the popliteal fossa, on the medial border of the tendon of biceps femoris.
Features
Lower He/sea point.
Body Inches (cun)
Each person has his/her own personal body inches.
One cun is equal to the width of the Knuckle of the thumb.
Nerves, vascular
Posterior femoral cutaneous nerve, common peroneal nerve and superior lateral arteries and veins.
Indication
Back muscle spasm ，low back pain，knee pain and swelling，gastrocnemius muscle spasm；nephritis，cystitis，chylous urine；lower abdominal spasm，epilepsy，fever. Damp heat conditions effecting the lower warmer: disperse for difficult urination. Tonify for urinary incontinence.
Combinations
Lumbago：BL 39 & BL 37 & SP 03.
Nephritis，difficulty in urination：BL 39 & SP 06 & BL 60.
Dribbling of urine：BL 39 & BL 52 & 3.BL 33.
Swollen of the axilla：PC 01 & BL 39.
Chylous urine：BL 22 & BL 28 & BL 39 & CV 03 & SP 06.
穴位
在膕橫紋外側端，當股二頭肌腱的內側。
特點
三焦下合穴。
同身寸
針灸取穴比量法。出自《千金要方》。
是指以患者本人體表的某些部位折定分寸，
作为量取穴位的長度單位。
穴區神經血管
股後皮神經，腓總神經和膝上外側動、靜脈。
適應症
腰背肌痙攣，腰背痛，膝腫痛，腓腸肌痙攣；腎炎，膀胱炎，乳糜尿；下腹部痙攣，癲癇，熱病等。
穴位配伍療法
腰痛：1.委陽 2.殷門 3.太白
腎炎，小便不利：1.委陽 2.三陰交 3.崑崙
小便淋瀝：1.委陽 2.志室 3.中髎
腋腫：1.天池 2.委陽
乳糜尿：1.三焦俞 2.膀胱俞 3.委陽 4.中極 5.三陰交