（精）会阴的解剖.pptVIP

Perineum General features Region of below pelvic diaphragm A diamond-shape space whose boundaries are those of the pelvic outlet Lower border of symphysis pubis Rami of pubis and ischium Ischial tuberosity Sacrotuberous ligament Tip of coccyx Perineum Two triangles The perineum is divided into anterior and posterior triangles by joining the ischial tuberosities with an imaginary line Urogenital region 尿生殖区 (anterior)－differs in male and female Anal region 肛区 (posterior) －similar in both sexes Anal region 肛区 Anal sphincters 肛门括约肌 Internal Smooth muscle (thickened circular muscle coat) Surrounds upper two-thirds of anal canal Autonomic nerve supply External Striated muscle Surrounds lower two-thirds of anal canal Three parts－subcutaneous, superficial and deep Innervation by anal nerves of pudendal nerve and branches of S4 Anal region 肛区 Anorectal ring 肛直肠环 At junction of rectum and anal canal Consists of thickened muscle Contributing structures Puborectalis Superficial and deep parts of sphincter ani externus Sphincter ani internus Anal region 肛区 Boundaries Apex－conjunctive area of inferior fascia of pelvic diaphragm and fascia covering the obturator internus Base－skin of anal region Medially－sphincter ani externus, levator ani, coccygeus and inferior fascia of pelvic diaphragm Laterally－ischial tuberosity, obturator internus and fascia Anal region 肛区 Ischioanal fossa 坐骨肛门窝 Anteriorly Forward projection of anterior recess of fossa between pelvic diaphragm above and urogenital diaphragm below Posteriorly Backward projection of posterior recess of fossa between gluteus maximus, sacrotuberous ligament and coccygeus Anal region 肛区 Ischioanal fossa 坐骨肛门窝 Contents Fat Internal pudendal artery and vein and their rectal branches Pudendal nerve and its inferior rectal branch Pudental canal 阴部管 (Alcock’s) －on the lateral wall of fossa Pudendal n. Internal pudendal a. and v. Anal region 肛区 Pudendal n. 阴部神经 leaves the pelvis through the infrapiriform foramen