Pelvis Structure and Function - PDF

Structure and Function of Pelvis Bi-Hung Peng, Ph.D. Department of Neurobiology  Bony Pelvis Important Points Major ligaments – Sacrotuberous & sacrospinous making greater and lesser sciatic foramina – Sacroiliac – Obturator foramen & membrane Major bone componen...

Structure and Function of Pelvis Bi-Hung Peng, Ph.D. Department of Neurobiology  Bony Pelvis Important Points Major ligaments – Sacrotuberous & sacrospinous making greater and lesser sciatic foramina – Sacroiliac – Obturator foramen & membrane Major bone components – Ilium, ischium, pubic Sex differences Clinical Issues Tumors Lymphatic Drainage Prostatic Hypertrophy Endometriosis Hysterectomy Hemorrhoids  Abdominopelvic Cavity A. Bisected lower trunk. B. Coronally sectioned lower trunk. The pelvis is the space within the pelvic girdle, overlapped externally by the abdominal and gluteal (lower limb) regions and the perineum. Bony Pelvis Comparison of pelvic girdles of male and female. Pelvic fracture Pelvic fractures may cause injury to pelvic soft tissues, blood vessels, nerves, and organs.  Sacrospinous Sacrotuberous Posterior View  GSF LSF Obturator foramen & membrane Internal View  Structures of the male pelvis In Entering – Rectum – Internal iliac vessels – Urinary bladder – Nerves – Prostate – Ureter – Seminal vesicles – Obturator nerve – Vas deferens Leaving – Obturator nerve – Nerves & vessels Test. Vessels Ureter  Structures of the female pelvis In Entering – – Ureter Uterus – – Ovarian vessels Ovary – Internal iliac vessels – Rectum – Nerves – Urinary bladder – Obturator nerve – Uterine tubes (oviducts, Leaving Fallopian tubes) – Round ligament of uterus – Obturator nerve – Nerves and vessels Vesc. Ut. Rect. Ut. Ureter Ov. Vessels  Pelvic peritoneum 6: rectovesical pouch 6: pouch of Douglas Sympathetic sensation Below the line ParaSympathetic sensation  Pelvic Musculature Lateral - obturator internus Floor – levator ani with puborectal sling – tendinous arch Posterior wall – coccygeus – piriformis Muscles of pelvic floor and walls Muscles of pelvic floor and walls D. Muscles of lesser pelvis. E. Obturator fascia and levator ani added to part D. PS, pubic symphysis.  Pelvic Floor LA TA P C Musculature  P OI C LA Pelvic Vasculature Post Div I O Ant Div Posterior View  Nerves of Pelvis Autonomic Somatic Sympathetic Motor Parasympathetic Sensory Visceral Sensory (Afferents)  Sacral Plexus (Somatic) Superior gluteal nerve Lumbosacral trunk Inferior gluteal nerve Sciatic nerve Obturator nerve (from lumbar plexus) Pudendal nerve Autonomic  Female Male Lum. Sym. Hypogastric Pl Sac. Sym. Pelv. Spl. Pelvic Pl.  Nerve supply to pelvis Sympathetic Somatic – Superior hypogastric plexus – Obturator nerves Inferior hypogastric – Sacral plexus plexuses Lumbosacral trunk, Pelvic plexus S1, S2, S3 and S4 – Sacral sympathetic chains Parasympathetic – Pelvic splanchnics Pelvic plexus Pelvic plexus - both sympathetic and parasympathetic  Rectum and Anal Canal Peritoneal relationships Relationships with other pelvic structures Blood supply and drainage Lymphatic drainage Nerve supply Functional anatomy  Rectal Fold External sphincter Internal sphincter  Anal Column Anal Valve Internal sphincter External sphincter Anal Sinus Internal and external sphincters Neural Control Parasympathetic – contraction of muscular wall Sympathetic – tonic contraction of the internal sphincter  Pectinate Line Hemorrhoid (internal vs external)  Urinary Bladder Peritoneal relationships Detrusor muscle Trigone Ureteric openings and valves Internal urethral sphincter Capacity Bladder Urethra  Urethra Prostatic Membranous – both male and female Penile (spongy part) Penis  Male Viscera Urinary bladder Prostate gland Seminal vesicles B SV P  Male pelvis demonstrating bed of bladder and position of empty and full bladder 65-75% of semen , alkaline fluid 15-30% 1% Posterior Wall of Prostatic Urethra Prostate Prostatic Enlargement, Prostatic Cancer, and Prostatectomy The prostate is of medical interest because benign enlargement or benign prostatic hyperplasia (BPH) is common after middle age. An enlarged prostate projects into the urinary bladder and impedes urination by distorting the prostatic urethra. The middle lobule usually enlarges the most and obstructs the internal urethral orifice. Prostatic cancer is common in men older than 55 years of age. In most cases, the cancer develops in the posterolateral region. This may be palpated during a digital rectal examination. A malignant prostate feels hard and often irregular. In advanced stages, cancer cells metastasize (spread) to the iliac and sacral lymph nodes and later to distant nodes and bone. The prostatic plexus, closely associated with the prostatic sheath, gives passage to parasympathetic fibers, which give rise to the cavernous nerves that convey the fibers that cause penile erection. A major concern regarding prostatectomy is that impotency may be a consequence. All or part of the prostate, or just the  Prostate Gland Prostatic urethra – Colliculus seminalis – Utricle – Ejaculatory duct openings – Prostatic ducts Prostatic hyperplasia Prostatic cancer and lymphatic drainage Functional Innervation of the Pelvis Parasympathetic innervation of contraction of bladder and rectum and stimulation of erection Sympathetic innervation of involuntary sphincters  Functional innervation for ejaculation and micturition Parasympathetic control of Micturition erection – Detrusor m. & internal Sympathetic control of – Emission sphincter m. – Ejaculation – Parasympathetic – Close internal urethral Detrusor m. sphincter Sensory Stimulation of pudendal – Sympathetic nerves Internal urethral sphincter Pudendal motor – Bulbospongiosus m. Female Pelvic Viscera Urinary Bladder Uterus Ovary Vagina Uterus-Vagina-Bladder Positions - Ureter  Female Urinary Bladder Structure – similar, trigone, ureteric openings Functional innervation similar to male Vascular supply and drainage similar to male Lymphatic drainage similar to male  Uterus Suspensory ligament Ureter of ovary Board ligament Round ligament of uterus Inferior epigastric artery Ligament of ovary Posterior fornix of vagina Cervix Vagina Ovary Infundibulum Fimbriae Fundus of uterus Uterus  Uterus Anatomic relations to other pelvic structures Relationship of cervix and vaginal canal Blood supply - uterine a. Lymphatic drainage Support Hysterectomy and anatomic issues  Pelvic Lymphatics Usually drain along course of pelvic vasculature Special interest – drainage of the rectum and the ovary Questions?