1. Anatomy and physiology of the female reproductive organs. The bony pelvis - anatomy, diameters, planes

Covers the internal and external female genital organs, with a table giving the anatomy and function of the vagina, uterus, fallopian tubes and ovaries, followed by their ligamentous supports and blood supply. Then describes the bony pelvis: its bones, false and true parts, and pelvic types. A table lists the inlet, mid-pelvis and outlet diameters with normal values, and another gives external pelvimetry measurements. Ends with the Michaelis rhomboid and the curved pelvic axis that makes the head rotate during birth.

Inside: 3 sections · 3 tables · 15 flashcards · 3 min

Topic 1 of 61 in the MU Sofia syllabus for Obstetrics and Gynaecology (Dental Medicine, Year 4). The free AceMed note covers it in 3 sections, about 224 words (3 min of reading), with 15 flashcards.

Introduction

The female reproductive tract has external genitalia (vulva) and internal organs (vagina, uterus, tubes, ovaries) held inside the bony pelvis, which is also the passage the fetus must negotiate at birth.

Internal genital organs

Supports and blood supply

Ligaments: cardinal (Mackenrodt) and uterosacral ligaments are the main supports; the round ligament keeps anteversion; the broad ligament carries the vessels; the infundibulopelvic ligament carries the ovarian vessels.
Arteries: uterine artery (from the internal iliac) crosses above the ureter 1.5–2 cm lateral to the cervix ("water under the bridge"), the key danger point in hysterectomy; ovarian arteries come from the aorta.
Pelvic floor: levator ani (pubococcygeus, iliococcygeus) and the perineal body support the organs.

The bony pelvis

The pelvis is formed by the two hip bones, the sacrum and the coccyx. The false pelvis lies above the linea terminalis; the true pelvis below it is the birth canal. The gynaecoid type (round inlet, about 50% of women) is the most favourable; android, anthropoid and platypelloid types are less favourable.

External pelvimetry

The Michaelis rhomboid on the lower back (about 11 × 11 cm) is symmetrical in a normal pelvis; a flattened or asymmetric rhomboid suggests a contracted or deformed pelvis.

The pelvic axis is curved (curve of Carus): the fetus enters the inlet with its head transverse and leaves the outlet with it anteroposterior, which is why the head has to rotate.