Pelvis and Female Reproductive Organs

• This lecture is about the pelvis, pelvic diaphragm, uterus, ovaries, and vagina
• The lecture covers renal and genito-urinary topics

Learning Outcomes

• Describe the anatomy of the bony pelvis and contrast male and female features
• Describe the obturator internus and piriformis muscles, including attachments and nerve supply
• Describe the muscles of the pelvic diaphragm, including attachments, parts, nerve supply, and their role in supporting pelvic organs
• Outline the role of the pelvic diaphragm in supporting the organs of the pelvis
• Describe the anatomy of the female genital organs
• Identify the uterus and vagina on radiological imaging
• Describe clinical conditions that may affect the cervix and uterus, such as carcinoma
• Describe the iliac vessels
• Describe the somatic & autonomic nervous structures of the pelvis

Female Reproductive Organs

• Consist of an ovary and uterine tubes on each side
• Consist of a uterus and the proximal half of the vagina in the midline

Ovaries

• Ovoid in shape
• Part of the mesovarium
• Ligaments include the ovarian ligament proper and the suspensory ligament
• Located in the Ovarian fossa, between internal/external iliac vessels
• The obturator nerve runs along here

Uterine Tubes

• Part of the mesosalpinx
• Connected to the ovarian ligament proper
• Sections
• Histology consists of outer longitudinal muscle, inner circular muscle, and columnar epithelium (ciliated & non-ciliated)

Uterus

• Made up of a body and a cervix
• The body comprised the fundus, isthmus of the uterus, and cornu (uterine horns)
• Body lies between the layers of the broad ligament
• The cervix contains the internal os and external os
• The body typically arches forward (anteflexed) on the cervix, approximately 170° over the superior surface of the emptied bladder
• The cervix is angled forward (anteverted) on the vagina, approximately 90°
• 20% of females retroverted
• Wall layers, from outer to inner, are:
  • Perimetrium: serous outer coat (peritoneum)
  • Myometrium: middle muscular layer
  • Endometrium: inner mucous layer

Vagina

• A fibromuscular collapsable tube that opens into the vestibule.
• The Cervix bulges into the vagina forming the anterior fornix, posterior fornix, and lateral fornices - The Posterior fornix related to the pouch of Douglas - Lateral fornices connect to the Ischial spine and Uterine artery & ureter

Cervical Examination and Cytology

• Used to gather cellular material from the supravaginal cervical mucosa.
• The Uterus is lined by columnar epithelium.
• The upper vagina is lined with stratified squamous non-keratinized epithelium
• At the external cervical os, the squamous epithelium changes to a tall columnar mucinous epithelium (squamocolumnar junction/transformation zone)

Pelvic Fascia

• In females, the anterior is the pubocervical ligament
• In females, the lateral is the transverse cervical or cardinal ligament including the uterine artery
• In females, the posterior is the uterosacral ligament
• In males, the puboprostatic ligament
• In males, the prostatic fascia and rectovesical septum

Peritoneal Reflection

• The superior surface of the bladder is covered by parietal peritoneum
• Reflections of peritoneum (from the bladder to surrounding viscera) create peritoneal pouches: Rectovesical pouch and Vesicouterine pouch

Broad Ligament

• Double layer of peritoneum that "drapes” over the uterus and tubes
• Includes the mesosalpinx and mesometrium

Lymphatics

• Ovaries, uterine tubes and fundus of the uterus drain to lumbar/para-aortic nodes
• Cornu of the uterus drain to the superficial inguinal
• Body of the uterus drains to external iliac lymph nodes
• The cervix and superior/middle parts of the vagina drain into internal iliac nodes.
• The external vagina, labia majora, and labia minora drain to superficial inguinal nodes

Clinical Conditions

• Uterine fibroids
• Endometrial carcinoma
• Cervical carcinoma
• Uterine prolapse
• Ectopic pregnancy, which can cause uterine tube bleeding
• Ovarian Cyst
• Ovarian Carcinoma

Organization of Pelvis

• The false pelvis (greater pelvis) is above the pelvic inlet and considered part of the abdominal cavity
• The true pelvis (lesser pelvis) is beneath the pelvic inlet and is bounded by the pelvic diaphragm

Pelvic Bones

• Irregular in shape
• Made up of the ilium, pubis, and ischium

Ligaments of the Pelvic Wall

• Convert notches into foramina (greater and lesser sciatic foramen)
• Stabilize the sacrum and prevent rotation

Joints

• Sacroiliac joints transmit forces from the lower limbs to the vertebral column and are stabilized by ligaments
• The pubic symphysis is a secondary cartilaginous joint with joint surfaces covered by hyaline cartilage

Apertures and Getaways

• Greater sciatic foramen
  • Above piriformis
    • Superior gluteal vessels
    • Superior gluteal nerve
  • Below piriformis
    • Inferior gluteal vessels
    • Inferior gluteal nerve
    • Sciatic nerve
    • Posterior femoral cutaneous nerve
    • Nerve to quadratus femoris
    • Pudendal nerve
    • Internal pudendal vessels
    • Nerve to obturator internus
• Lesser sciatic foramen
  • Pudendal nerve
  • Internal pudendal vessels
  • Nerve to obturator internus
  • Obturator internus muscle

Pelvic Cavity

• Contains a pelvic inlet, walls, floor, and pelvic outlet with Hip bone, Sacrum, Sacrospinous ligament, and Sacrotuberous ligament
• Lateral wall muscles: Piriformis and Obturator internus
• Floor muscles: Levator ani and Coccygeus

Pelvic Walls-Lateral

• Obturator internus on the deep surface of the obturator membrane to the greater trochanter
• The obturator internus is innervated by the nerve to obturator internus and laterally rotates the extended hip.
• Piriformis runs from the anterior surface of the sacrum to the greater trochanter
• The piriformis is innervated by S1 & S2 and laterally rotates the extended hip

Pelvic Floor

• Separates the pelvic cavity and the perineum
• Consists of the Pelvic diaphragm, Perineal membrane, and Muscles of the deep perineal pouch including the Levator ani and Coccygeus
• The Levator ani originates from a line that extends from the pubic bone to the ischial spines/inserts into the muscle from the other side and is innervated by S2-4 via direct branches of the pudendal nerve

Pelvic Inlet and Outlet

• The pelvic inlet is heart-shaped and completely ringed by bone: Promontory, Alae , Sacro-iliac joint, Linea terminalis, and Pubic symphysis
• The pelvic outlet is diamond-shaped: Pubic symphysis, Body of the pubis, Inferior ramus of the pubis, Ramus of the ischium, Ischial tuberosity, Sacrotuberous ligament, and Coccyx

Sexual Difference in the Pelves

• Female Pelvic Inlet is Circular, Male is Heart-shaped
• Female sacrum is less distinct with broarder alae vs male is narrower
• Female Pubic angle Larger (80°-85°) vs male (50°-60°)
• Female Ischial spines provide Less medial projection into the pelvic cavity vs male

Pelvic Measurements

• Obstetric measurements include Conjugate (AP), Conjugate diagonal, Transverse, and Interspinous diameter (narrowest)-outlet

Blood Supply

• The aorta begins at T12 and bifurcates at L4 as the common iliac arteries
  • Common iliac bifurcates at the sacroiliac joint into internal and external
• External iliac becomes femoral at the level of the inguinal ligament -Internal iliac gives off anterior and posterior branch -Anterior: 3 parietal and 3 visceral -Posterior: 3 parietal