Pelvis and Perineum Anatomy PDF

PELVIS AND PERINEUM THE PELVIS The region located between the abdomen and the lower extremity. 1. Provides support for lower abdominal, urogenital and reproductive organs. 2. A point of attachment of muscles and lig...

PELVIS AND PERINEUM THE PELVIS The region located between the abdomen and the lower extremity. 1. Provides support for lower abdominal, urogenital and reproductive organs. 2. A point of attachment of muscles and ligaments. 3. Includes the: a. Bony pelvis (covered in LL lectures) b. Pelvic cavity – space enclosed by the bones (covered in LL lectures) c. Pelvic floor – pelvic diaphragm d. Perineum e. Urogenital diaphragm f. External genitalia PELVIC FLOOR/PELVIC DIAPHRAGM  PELVIC DIAPHRAGM 1. The region inferior to the pelvic cavity. 2. Separates the pelvic cavity from the perineum. 3. Provides support for the pelvic viscera (bladder, uterus etc.) 4. Damage can lead to prolapse of the pelvic organs and urinary incontinence. 5. Pelvic floor exercises aka Kegel exercises improve the tone of the pelvic muscles. 6. Muscles: a. Ischiococcygeus/Coccygeus b. Levator ani: i. Iliococcygeus INFERIOR VIEW ii. Pubococcygeus iii. Puborectalis Pelvic diaphragm (Levator ani muscle + Coccygeus) OBTURATOR INTERNUS MUSCLE AND FASCIA ISCHIOCOCCYGEUS (COCCYGEUS) MUSCLE TENDINOUS ARCH OF THE LEVATOR ANI EXTERNAL ANAL SPHINCTER MUSCLE LEVATOR ANI MUSCLE MEDIAL VIEW PELVIC DIAPHRAGM (Levator ani muscles + coccygeus) MALE FEMALE  MUSCLE ORIGIN INSERTION CHARACTERISTICS ISCHIOCOCCYGEUS Ischial spine Vertebrae S4-Cx2 (coccygeus) LEVATOR ANI Iliococcygeus Tendinous arch of the Coccyx levator ani Pubococcygeus Pubic arch and the Coccyx tendinous arch of the levator ani Puborectalis Pubic arch Midline and rectum Most medial. Forms a rectal sling. Some fibers pass posterior to the vagina (pubovaginalis), and posterior to the prostate (puboprostaticus) THE PERINEUM THE PERINEUM 1. The area of the trunk inferior to the pelvic diaphragm which overlies the pelvic outlet (inferior pelvic aperture). 2. In the anatomical position, it is a narrow area between the thighs. U 3. When the thighs are abducted, the perineum is a A diamond-shaped area: a. Lateral – ischial tuberosities b. Anterior – pubic symphysis c. Posterior – coccyx 4. The transverse diameter, a line connecting the ischial tuberosities, divides the perineum into the urogenital triangle (U) anteriorly and anal triangle (A) posteriorly. U A 5. These triangular areas share the levator ani muscle and have the same innervation and blood supply. 6. Each triangle, however, has its own special musculature. THE PERINEUM Female A. Structures of the urogenital triangle (U): 1. external genitalia U 2. musculature A 3. erectile tissues 4. gonads in the male Male B. Structures associated with the anal triangle (A): 1. anal canal and anus U 2. external anal sphincter muscle A 3. Ischioanal fossa 4. Pudendal nerve ANAL TRIANGLE  ANAL TRIANGLE MALE FEMALE 1. The posterior half of the perineum. 2. This triangle is structurally the same in both sexes. 3. Borders - theoretical transverse line between the ischial tuberosities and lines between the coccyx and ischial tuberosities bilaterally. 4. The floor is formed by the levator ani muscle group. 5. The walls are formed by the obturator internus muscle(anterolaterally) and the sacrotuberous ligament with the overlying gluteus maximus muscle (posteriorly).  ANAL TRIANGLE MALE FEMALE CONTENTS: 1. Anal canal and anus 2. External anal sphincter muscle 3. Ischiorectal (Ischioanal) fossa: a. bilateral spaces filled with fat; lateral to the anus b. Allows for the expansion of the anus during defecation c. Pudendal (Alcock’s) canal – a fascial tunnel on the lateral wall of the ischiorectal fossa. Contents: i. Pudendal nerve ii. Internal pudendal vessels  ANAL TRIANGLE Ischiorectal/ischioanal fossa INTERNAL PUDENDAL VESSELS “exit” from & PUDENDAL Pudendal NERVE (Alcock’s) canal PERINEALBODY ISCHIORECTAL FOSSA Ischiorectal fossa is prone to INFERIOR abscesses: “horseshoe” abscesses. RECTAL VESSELSAND NERVE FEMALE UROGENITAL TRIANGLE  UROGENITAL TRIANGLE MALE FEMALE 1. The anterior half of the perineum. 2. Borders - Theoretical transverse line between the ischial tuberosities and lines between the ischial tuberosities and the pubis bilaterally. 3. It contains a superficial and a deep perineal pouch. 4. Layers from superficial to deep : a. Skin b. Perineal fascia c. Superficial perineal pouch d. Perineal membrane e. Deep perineal pouch  UROGENITAL TRIANGLE 1. Perineal fascia: a. Superficial fascia has two layers: i. Superficial layer continuous with Camper’s fascia of the abdominal wall. ii. Deep layer (Colles’ fascia) continuous with Scarpa’s fascia of the anterior abdominal wall. Superior fascia of UG diaphragm perineal membrane(inf. fas. UG diap.) b. Deep fascia – covers the ischiocavernosus, Colles’ fascis bulbospongiosus, and superficial transverse perineal muscles 2. Superficial perineal pouch:  between the Colles’ fascia and perineal membrane (inf. fascia of UG diaphragm). 3. Deep perineal pouch:  between the perineal membrane and the superior fascia of the pelvic diaphragm.. SUPERFICIAL PERINEAL POUCH Deep Superficial SUPERFICIAL PERINEAL POUCH DEEP PERINEAL SPACE/POUCH  LOCATED IN THE UROGENITAL TRIANGLE OF THE PERINEUM BELOW THE PELVIC DIAPHRAGM  UROGENITAL (UG) DIAPHRAGM 1. The urogenital diaphragm is located between the superior fascia of the UG diaphragm and inferior fascia of UG diaphragm (perineal membrane). 2. The urogenital diaphragm is penetrated by the urethra in the male (membranous urethra) and the urethra and vagina in the female. 3. Contents: a. External urethral sphincter muscle (Sphincter urethrae) i. Regulates the outflow of urine from the bladder into the urethra ii. In the male – at the level of the membranous urethra b. Deep transverse perineal muscles  Extends horizontally between the two ischiopubic rami to the perineal body.  PUBIC MONS PUBIS SYMPHYSIS INFERIOR CLITORIS RAMUS OF PUBIS EXTERNAL URETHRALORIFICE LABIAMINORA SPHINCTER URETHRAE M. VAGINA SUPERFICIAL INTERNALPUDENDAL TRANSVERSE VESSELS PERINEAL AND PUDENDALNERVE MUSCLE INFERIOR FAT RECTAL VESSELS ISCHIORECTAL AND NERVE FOSSA GLUTEUS LEVATOR MAXIMUS ANI MUSCLE DEEPTRANSVERSE PERINEAL M. PERINEAL BODY/ CENTRAL TENDON OF PERINEUM PERINEAL BODY/CENTRAL TENDON OF PERINEUM 1/3 1. A fibromuscular mass located at the junction of the urogenital and anal triangles. 2. Located in the median plane. 3. Located just deep to the skin between the anal canal and the vaginal orifice in the female, and the bulb of the penis in the male. 4. Site of attachment for muscles of the pelvic diaphragm and the perineum. PERINEAL BODY/CENTRAL TENDON OF PERINEUM 2/3 1. The perineal body provides the pelvic diaphragm with “support”. 2. It acts as support for the posterior wall of the vagina 3. It may be damaged during childbirth.  If it is damaged during natural childbirth, it could compromise the integrity of the pelvic diaphragm. 4. Episiotomy - a procedure whereby an incision is made to increase the diameter of the vaginal canal during delivery to allow easier exit of the fetal head The incision is made lateral to the perineal body.  3/3 Structures attach to the perineal body: 1. Superficial and deep transversus perineal muscles 2. Bulbospongiosus muscle 3. Levator ani muscle 4. External anal sphincter muscle 5. Superficial and deep perineal fascia NOTE: The ischiocavernosus muscle does NOT attach to the perineal body. FEMALE UROGENITAL TRIANGLE  FEMALE UROGENITAL TRIANGLE Contents: 1. External genitalia: a. The mons pubis b. The labia majora c. The labia minora Ischiocavernosus m. 2. Perineal muscles: Bulbospongiosus m. Transverse perineal m. a. Superficial and deep transverse perineal muscles b. Bulbospongiosus muscles c. Ischiocavernosus muscles covers the two crura of the clitoris FEMALE UROGENITAL TRIANGLE Contents (continue): 3. Erectile tissues: a. The clitoris b. Bulb of the vestibule FEMALE EXTERNAL GENITALIA (VULVA) 1. MONS PUBIS: a.Rounded fatty median eminence located anterior to the pubic symphysis. b.Fat increases during puberty and decreases after menopause. c.Skin is covered with coarse hair. 2. LABIA MAJORA: a. Two longitudinal skin folds that extends from the pubis (anteriorly) near the anus (posteriorly). b. Anteriorly, they are united by the anterior labial commissure c. Posteriorly, they are united by the posterior labial commissure. 3. LABIA MINORA: a. Thin folds of fat-free, hairless skin. b. Located between the labia majora. FEMALE EXTERNAL GENITALIA (CONT’D) 3. LABIA MINORA (continue): c. Deep to the labia minora is the Bulbospongiosus muscle. d. Deep to the Bulbospongiosus muscle is the Bulb of the vestibule. Greater Vestibular glands – posterior to bulb of vestibule; secrete lubricating mucus. They are homologous to the male Bulbourethral glands. e. The vestibule of the vagina is the area between the two labia minora containing the openings for the urethra (anterior) and the vagina (posterior) 4. CLITORIS: a. Erectile organ homologous to the penis. b. It consists of: i. Root ii. Body Two crura Two corpora cavernosa (erectile tissue) Glans clitoris c. Located posterior to the anterior labial commissure, and anterior to the urethral and vaginal orifices BLOOD & NERVE SUPPLY OF EXTERNAL GENITALIA 1. BLOOD SUPPLY: a. Internal pudendal artery (branch of Internal iliac artery) b. External pudendal artery (branch of Femoral artery) 2. INNERVATION: a. Ilioinguinal nerve (L1) b. Genital branch of the genitofemoral nerves (L1-L2) MALE UROGENITAL TRIANGLE MALE UROGENITAL TRIANGLE TESTES CONTENTS: 1. External genitalia a. The penis which encloses the urethra b. The scrotum which houses the male gonads-testes 2. Perineal muscles a. Superficial and deep transverse perineal muscles b. Bulbospongiosus muscles c. Ischiocavernosus muscles – lateral aspect of the perineum which covers the crura or corpora ISCHIOCAVERNOSUS M. cavernosa TRANSVERSE BULBOSPONGIOSUS M. 3. Erectile tissues PERINEAL M. a.Corpora cavernosa b. Corpus spongiosum 4. Gonads - testes 5. Epididymis 6. Spermatic cord  MALE EXTERNAL GENITALIA – THE PENIS 1. Male copulatory organ 2. Dual roles: a. Reproductive – passage of BODY semen b. Urinary – passage of urine 3. Parts: a. Root ROOT b. Body c. glans penis  MALE EXTERNAL ISCHIOCAVERNOSUS M. GENITALIA – THE PENIS TRANSVERSE BULBOSPONGIOSUS M. The root has two muscles and erectile PERINEAL M. tissues deep to the muscles: 1. Ischiocavernosus muscles: extend from the ischial tuberosity on the lateral aspect of the urogenital triangle.  Cover the left and right crura which are erectile tissues. 2. Bulbospongiosus muscle: extend from the perineal body on the medial aspect of the urogenital triangle.  Covers the bulb of the penis The body contains the erectile tissues: 1. Corpora cavernosa (2)- continuation of the left and right crura 2. Corpus spongiosum (1) – continuation of the bulb. It expands distally as the glans penis BLOOD SUPPLY - PENIS ARTERIAL SUPPLY: 1. Dorsal artery of the penis 2. Deep arteries of the penis 3. Artery of bulb  All are branches of the internal pudendal artery, which is a branch of internal Iliac artery. VENOUS RETURN: 1. Deep dorsal vein 2. Superficial dorsal veins THE SCROTUM 1. Fibromuscular sac that houses and protects the testes and associated structures. 2. Keeps the testes at optimum temperature for spermatogenesis. 3. Cremaster muscle responsible for raising and lowering the scrotum. 4. Located posteroinferior to the penis and inferior to the pubic symphysis. 5. Divided into two compartments by a septum which houses each testis.  BLOOD & NERVE SUPPLY OF SCROTUM BLOOD SUPPLY: 1. Posterior scrotal artery – terminal br. of internal pudendal artery 2. Superficial and deep br. of external pudendal artery 1 NERVE SUPPLY: 2 1. Anterior scrotal n. (br. of ilioinguinal n.) 2. Genital branch of the genitofemoral n. 3 3. Posterior scrotal nerve (terminal br. of pudendal n.) THE TESTES & EPIDIDYMIS THE TESTES 1. The male gonad homologous to the ovary in the female. 2. Dual roles: a. Exocrine – production of sperm b. Endocrine – production of testosterone 3. Connected to the pelvic viscera via the spermatic cord, which contains: a. Ductus deferens (vas deferens) b. Testicular artery and vein (pampiniform plexus) c. Lymphatic vessels THE EPIDIDYMIS 1. Comma-shaped structure located on the posterior surface of the testes. 2. It consists of a head, body, and tail that is continuous with the ductus deferens. 3. FUNCTION: Storage and maturation of sperm. PELVIC ARTERY - INTERNAL ILIAC ARTERY A. POSTERIOR TRUNK: 1. Iliolumbar artery 2. Lateral sacral artery 3. Superior gluteal artery B. ANTERIOR TRUNK: 1. Inferior gluteal artery 2. Obturator artery 3. Umbilical artery a. Superior vesical artery b. Middle vesical artery 4. Uterine artery 5. Deferential artery 6. Middle rectal (hemorrhoidal) 7. Inferior vesical artery 8. Internal pudendal artery a. Inferior rectal artery b. Scrotal/labial artery c. Perineal artery d. Deep and dorsal arteries of the penis  PELVIC ARTERIES – Male and Female A & B. 1.-iliolumbar 2.-sup. gluteal 3.-lat. sacral 4.-umbilical ->sup. vesical 5.-obturator 6.- inf. vesical 7.-mid. rectal 8.-int. pudendal ->inf. rectal 9.-inf. gluteal. B. uterine & vaginal aa. directly from ant. div. of int. iliac a.  PELVIC VEINS 1. Small veins of the pelvic cavity generally follow the arteries in the region 2. They drain into the internal iliac vein which reaches the inferior vena cava by way of the common iliac veins. NERVE SUPPLY OF THE PELVIS Lumbosacral Plexus Questions?