Anatomy of Pelvic Arteries and Veins

Vascular Anatomy of the Pelvis

• The pudendal artery exits the pelvic cavity via the sciatic foramen, supplying inferior rectal, perineal, and vulval arteries.
• The superior rectal artery continues from the inferior mesenteric artery, descending in the mesocolon and branching to supply the rectum.
• Pelvic veins drain the uterine, vaginal, and vesical plexuses into internal iliac veins; rectal plexus drains via superior rectal veins to inferior mesenteric veins, and middle/inferior rectal veins to internal pudendal then to iliac veins.
• Ovarian veins arise from the pampiniform plexus; the right ovarian vein drains into the inferior vena cava, while the left drains into the left renal vein.
• Lymphatic drainage from lower extremities, vulva, and perineal regions is through inguinal and superficial femoral nodes, then to external iliac, common iliac, and para-aortic nodes.

Anatomy of the External Genitalia

• The vulva includes mons pubis, labia majora, labia minora, vaginal vestibule, clitoris, and greater vestibular glands.
• Mons pubis: a fibrofatty pad covered with hair.
• Labia majora: skin folds containing sebaceous and sweat glands, positioned alongside the vaginal opening.
• Labia minora: thinner skin folds between labia majora, containing sebaceous glands but no adipose tissue.
• Clitoris: a small erectile structure (0.5-3.5 cm) composed of corpora cavernosa.
• Vaginal vestibule: contains openings for the urethra, Bartholin’s glands, and vagina.
• Bartholin’s glands: bilateral glands contributing to lubrication during intercourse, opening via ducts into the vestibule.
• The hymen: a mucous membrane covering the vaginal entrance, typically perforated during menstruation and may rupture during intercourse.

Internal Reproductive Organs

• The vagina is a fibromuscular canal (9cm posteriorly, 7cm anteriorly) lined with stratified squamous epithelium; its moisture is maintained by secretions from uterine and cervical glands.
• Pelvic fascia includes parietal and visceral layers, supporting pelvic organs and providing attachment points for key ligaments.
• Cardinal ligaments support the uterus and vaginal vault, while utero-sacral ligaments extend to the sacrum.

Uterus Anatomy

• The uterus is an inverted pear-shaped organ measuring 7.5 cm in length, with a tapered cervix projecting into the vagina.
• Divided into three main layers: serous layer (peritoneum), muscular layer (myometrium), and mucous layer (endometrium).
• The endometrium undergoes cyclical changes during menstruation, with thickness varying from 1-5 mm.

Cervix and Fallopian Tubes

• The cervix: about 2.5 cm long, surrounded by parametrium, has glandular follicles secretive of alkaline mucous; transition from columnar to stratified squamous epithelium at the external os known as the transformation zone.
• Fallopian tubes extend from the uterus to ovaries, covering 10 cm in length; they consist of four parts: interstitial, isthmus, ampulla, and fimbrial portion, with a ciliated epithelium and muscle layers.

Summary of Key Physiological Changes

• At puberty, the vulva develops hair and fat deposits; after menopause, the labia minora thins.
• The vagina's epithelium is rich in glycogen during the post-ovulatory phase, and its pH ranges around 4.5 due to Doderlein’s bacillus.
• Hypertrophy of the vagina occurs at birth and at puberty but atrophies post-menopause.

This quiz covers the anatomy of the pudendal artery and the superior rectal artery, including their origins, branches, and the venous drainage system associated with the pelvic organs. Test your knowledge on the arterial supply and venous drainage of the perineal and pelvic regions.