1. UTERUS

Basic Facts

• Shape: Pear-shaped, located in the pelvic cavity
• Functions:
  • Implantation of the fertilized egg
  • Hormonal response (to ovarian hormones)
  • Carries and nourishes the developing baby
  • Can increase in size via hypertrophy + hyperplasia

Parts of the Uterus

• Fundus — the dome-shaped top
• Body (Corpus) — the main middle section; body is divided into:
  • Body proper — contains the uterine cavity; responds to hormonal stimuli
  • Fundus
• Isthmus — a narrow zone inside the body (0.5 cm), the "first constriction after the cavity"
• Cervix (2.5 cm) — the lower cylindrical portion

Uterine Measurements (Nulliparous)

Internal Os

• Has two types:
  • Anatomical internal os — the actual constriction point
  • Histological internal os — where the epithelium changes (simple columnar → glandular, multi-branched); no hormonal response here
• During pregnancy (3rd trimester), the anatomical internal os becomes the lower uterine segment — the fetal membrane does not attach here, making it the safe incision site for LSCS (Lower Segment Caesarean Section)

Cervix

• Located between the internal and external os
• Has a transformation zone — junction of simple squamous and columnar epithelium
• This zone is the most common site for cervical carcinoma (MCQ high-yield point)
• The cervical canal + uterine cavity = 6 cm total

2. POSITIONS OF THE UTERUS

• Angle between cervix and vagina = 90°
• Anteversion = normal forward tilt of the uterus relative to the vagina
• Angle between body and cervix = 125° (anteflexion)
• Anteversion is maintained by: Round ligament of the uterus + Uterosacral ligament

Retroverted Uterus (abnormal)

1. Infertility
2. Heavy menstrual bleeding

3. RELATIONS OF THE UTERUS

• Anterior: Urinary bladder
• Posterior: Rectum

4. BLOOD SUPPLY OF THE UTERUS

Arterial Supply

• Main supply: Uterine artery (branch of internal iliac artery)
• The uterine artery is tortuous (like the facial artery — a memorable teaching point from the notes)
• Branches: Anterior & posterior → Coronary/Arcuate artery → Radial artery → Arterial plexus in stratum vasculare of myometrium → splits into:
  • Straight artery (Stratum Basale) — no hormonal response
  • Coiled/Spiral artery (Stratum Functionale) — responds to hormones; shed during menstruation

Venous Drainage

• Uterine vein → Internal iliac vein
• Also: Ovarian vein, splenic vein pathways mentioned

5. THREE LAYERS OF THE UTERUS

1. Endometrium — inner lining; has functional layer (responds to hormones, shed during menstruation) and basal layer (does not respond)
2. Myometrium — muscular middle layer
3. Perimetrium — outer serous covering

6. LYMPHATIC DRAINAGE

Uterine Body

• Upper segment (fundus): drains to lateral aortic (pre- and para-aortic) nodes
• Middle segment: external iliac nodes
• Lower segment: internal iliac nodes

Cervix

• Drains to: External iliac, Obturator, Internal iliac nodes (mnemonic noted: SEIO)

Endometrial Cancer lymphatics — 3 segments: upper, middle, lower

7. NERVE SUPPLY OF THE UTERUS

• Sympathetic (T12–L1/2): causes vasoconstriction, uterine contraction, carries pain from the body
• Parasympathetic (S2–4): causes vasodilation, uterine inhibition, carries pain from the cervix

8. FALLOPIAN TUBES

• Total length: 10 cm
• Has 2 openings: uterine side (uterine ostium) and ovarian side (abdominal ostium)
• 4 Parts (medial to lateral):
  1. Intramural (narrowest) — passes through the uterine wall
  2. Isthmus
  3. Ampulla (most dilated) — most common site of fertilization
  4. Infundibulum (finger-like fimbriae) — the ovarian fimbria is the largest and acts as a sensor

Blood Supply

• Uterine artery + Ovarian artery

Venous Drainage

• Uterine vein + Ovarian vein

9. CLINICAL CORRELATIONS — Fallopian Tube

• Salpingitis: Inflammation of the fallopian tube; commonest cause of tubal block → secondary sterility. Tested by:
  • (a) Insufflation (Rubin's) Test — air pushed into uterus; if patent, leaks into peritoneum (hissing/bubbling sound heard with stethoscope over iliac fossa)
  • (b) Hysterosalpingography (HSG) — radiopaque dye (Lipiodol) injected; outlines the cavity and tubes
• Ectopic Pregnancy: Most common in the uterine tube (tubal gestation); causes intraperitoneal hemorrhage → acute abdominal emergency due to tube rupture
• Tubectomy: Female sterilization — each tube ligated at two points and the segment between is resected; prevents fertilization; ideal method of family planning

10. OVARY

• Shape: Almond-shaped structure
• Position differs in nulliparous vs. multiparous women
• Blood supply: Ovarian artery (from aorta) + Uterine artery
• Venous drainage: Pampiniform plexus →
  • Right ovarian vein → IVC
  • Left ovarian vein → Left renal vein

Ovarian Fossa Contents

1. Ureter
2. Internal iliac artery/vein
3. Obturator artery/vein

Ovarian Histology (3 layers)

1. Surface epithelium — germinal epithelium (no pathology from here noted)
2. Cortex — contains follicles (primary, secondary, tertiary, preovulatory) and corpus luteum/corpus albicans
3. Medulla — connective tissue, blood vessels (arteries + veins), meshwork of CT

11. CLINICAL CORRELATIONS — Ovary

• Ovarian torsion — due to abnormally long mesovarium/suspensory ligament
• Prolapse of ovaries — displaced into Pouch of Douglas; palpable on PV examination
• Ovarian cyst — from arrested follicle development or corpus luteum of pregnancy (causes AP abdominal bulging; no shifting dullness — differentiates from ascites)
• Ovarian carcinoma — accounts for ~15% of all cancers and ~20% of gynecological cancers

Summary

• Anatomical measurements and part names
• Clinical significance (LSCS, ectopic pregnancy, cancer sites)
• Vascular supply, nerve supply, and lymphatic drainage
• High-yield MCQ points (transformation zone, spiral arteries, ampulla as fertilization site, left ovarian vein draining to left renal vein, etc.)