ANATOMY, FEMALE GENITALIA

Model of the internal anatomy of an adult female pelvis (median section).
Here, removal of the digestive organs and the internal genitalia makes it possible to view the pelvic wall.
The internal surface of the anterior pelvic wall (on the left of the picture) is covered by the superficial fascia including fat (in yellow). It is followed by the rectus abdominis muscle (in red), which is bordered by a thick aponeurosis membrane (white line).
The pelvic vascular network (arteries in red and veins in blue) includes: the common iliac artery (derived from the abdominal aorta, bringing oxygenated blood to the lower part of the body) and the common iliac vein draining deoxygenated blood from the pelvis and the lower limbs towards the inferior vena cava. In the lumbar intervertebral disc region, the common iliac artery divides into internal (posterior) and external (anterior) iliac arteries, irrigating the pelvic structures and the lower limbs, respectively. The internal iliac artery next bifurcates into an anterior section (giving the obturator, umbilical, uterine, rectal and internal pudendal arteries) and a posterior section, dividing in the sacral area. The common iliac vein transports the blood coming from the internal and external iliac veins, receiving a network of veins with names corresponding to the arteries. The ovarian artery and vein, irrigating the ovaries and the Fallopian tubes, run alongside below the ureter (in greenish yellow) bringing urine from the kidney to the urinary bladder. The inferior epigastric vessels, branches of the external iliac vessels, irrigate the abdominal wall. The obturator nerve (in yellow) arises from the lumbar plexus and goes down vertically inside the pelvis; it passes under the external iliac vessels and innervates the thigh muscles.
On the lateral pelvic wall lies the iliacus muscle (in red) followed by the psoas major muscle, flexor of the hip. Located on the right of the common iliac vessels, the obturator internus muscle enables thigh rotation around the pelvis; it extends towards the tendinous arch (in white) of the levator ani muscle, covering the pelvic floor. In the posterior area, the sacral plexus (in yellow) rests on the piriformis muscle.
Below, the female genitalia includes the pubis, a protusion of fatty tissue covering the pubic symphysis (pelvic bone, bluish), the labia majora and minora of the vulva (cutaneous folds) and the clitoris (in flesh color, located in front of the labia minora). The urethra, draining urine from the bladder, and the ostium of the vagina open at the labia minora level. The vaginal mucosa shows numerous folds, known as the vaginal rugae. To the rear, the lower part of the rectum, the anal canal, opens on the anus. The rectal wall includes three tissue layers: an outer muscularis (in orange-red), made up of muscle fibers enabling defecation, a middle submucosa layer and an inner mucosa (in orange) with vertical folds, the anal columns. The opening of the anus is controlled by an internal anal sphincter, composed of smooth muscle (in orange, reflex opening for defecation) and an external anal sphincter of striated muscle (in red, voluntary relaxation).
Dorsally, the spine ends with the lumbar area, of which the fifth vertebra is visible here; it is followed by the sacrum, a bone resulting from the fusion of the five sacral vertebrae, then by the coccyx. Between each vertebra lies an intervertebral disc for softening shocks. A vertebra is anteriorly composed of the vertebral body and posteriorly of the neural arch; they form a space, the vertebral foramen. The stacking of the vertebrae creates the vertebral canal containing the spinal cord. The latter extends towards the second lumbar vertebral region, and is anchored to the coccyx through a group of nerve fibers, the cauda equina (in light yellow). The first four sacral nerves, S1 to S4, are shown (in yellow); their roots leave the sacral foramina and innervate the digestive organs and genitalia. The first three sacral nerves, with the last two lumbar nerves (L4 and L5), constitute the sacral plexus; they converge to form the sciatic nerve innervating the lower limbs. Branches from the S2 to S4 sacral nerves constitute the pudendal plexus forming the pudendal nerve, that innervates the perineal muscles and the genitalia.