Anatomy of the Female Pelvis Gareth Davies Pelvis Male vs Female Male = Deep Greater Pelvis, Narrow pelvic inlet, small pelvic outlet, Narrow Subpubic angle (<70 degrees) Female = Shallow Greater Pelvis, Wide pelvic inlet, large pelvic outlet, wide Subpubic angle (>80 degrees) Pelvic Inlet (a) Gynaecoid—normal. (b) Symmetrically contracted pelvis small woman with symmetrical shape. (c) Android — masculine pelvis. (d) Platypelloid — shortened in the anteroposterior diameter, increased in the transverse diameter (the ‘nonrachitic flat pelvis’). (e)The Rachitic flat pelvis - rickets (f) Anthropoid— lengthened anteroposterior and a shortened transverse diameter. (g) Asymmetrical - scoliosis, longstanding hip disease (e.g. congenital dislocation), poliomyelitis, pelvic fracture, Naegele pelvis Joints • Sacroiliac – Anterior –> Synovial – Posterior --> Syndesmosis Ligaments • Anterior, Interosseous, Posterior Sacroiliac ligaments • Pubic Symphysis – Secondary Cartilaginous joint Sacrospinous, Sacrotuberous ligaments Urogenital and Anal Triangles Urogenital Triangle Anal Triangle Ischio-anal fossae Infection passes easily from one side to the other Can be due to boils or abrasions of the perianal skin, from lesions within the rectum and anal canal, from pelvic infection bursting through levator ani or, rarely, via the bloodstream. External Genitalia Deep Perineal Pouch Injury to Pelvic Floor During Childbirth • Can cause tearing of pubococcygeus • Pubococcygeus encircles and supports – urethra, vagina, anal canal. • Alteration of position of neck of bladder and urethra – may lead to urinary stress incontinence • Episiotomy Female Urethra • Approx 4cm long • Musculature surrounding the internal urethral orifice is not organised into an internal sphincter • More easily distensible than male urethra (increased elastic tissue) means catheters are more easily placed. • Paraurethral glands (homologue of the prostate) Pelvic Viscera Ligaments Infection – Peritonitis Salpingitis Round Ligament of uterus Ovarian Ligament Suspensory Ligament of Ovary Broad Ligament - Mesometrium - Mesovarium - Mesosalpinx Transverse cervical (Mackenrodt) ligament provides main passive support to uterus Dynamic support provided by perineal muscles Together help to prevent prolapse The most important single practical relationship in this region is that of the ureter to the supravaginal cervix. At this point, the ureter lies just above the level of the lateral fornix, below the uterine vessels as these pass across within the broad ligament. In performing a hysterectomy, the ureter may be accidentally divided in clamping the uterine vessels, especially when the pelvic anatomy has been distorted by a previous operation, a mass of fibroids, infection or malignant infiltration. the ureter lies 12 mm lateral to the supravaginal cervix. When can ureteric calculi be palpated? Blood supply to the ureter In abdomen – From Medial side In Pelvis – From lateral Side Innervation of the Perineum Innervation of the perineum: Pudendal nerve Innervation of the anterior part of the mons pubis provided by ilioinguinal and genitofemoral nerves from the lumbar plexus – anterior labial nerves Pelvic Pain Line • the pelvic pain line corresponds to the inferior limit of the peritoneum (in the GIT it occurs midway along the sigmoid colon) • Superior structures travel via sympathetic afferents • Inferior travels via parasympathetic