Pelvis Anatomy Set 3

The genital swellings, known in the male as the scrotal swellings, arise in the inguinal region. With further development, they move caudally, and each swelling then makes up half of the scrotum.

In young women, especially virgins, the labia minora are connected by a small fold known as the frenulum of the labia minora or the fourchette.

Distally the corpus spongiosum expands to form the conical glans penis.

Except for the most cranial portion, the appendix epididymis, the mesonephric ducts persist and form the main genital ducts. Immediately below the entrance of the efferent ductules, the mesonephric ducts elongate and become highly convoluted, forming the ductus epididymis. From the tail of the epididymis to the outbudding of the seminal vesicle, the mesonephric ducts obtain a thick muscular coat and form the ductus deferens. The region of the ducts beyond the seminal vesicles is the ejaculatory duct. Except for a small portion at their cranial ends, the appendix testis, the paramesonephric ducts in the male degenerate.

Some obstetricians apply the term perineum to a more restricted region that includes the area between the vagina and anus.

The deep arteries of the penis are the main vessels supplying the cavernous spaces in the erectile tissue of the corpora cavernosa and are therefore involved in the erection of the penis. They give off numerous branches that open directly into the cavernous spaces. When the penis is flaccid, these arteries are coiled and therefore are called helicine arteries.

Descent of the gonads is considerably less in the female than in the male, and the ovaries finally settle just below the rim of the true pelvis. The cranial genital ligament forms the suspensory ligament of the ovary, whereas the caudal genital ligament forms the ligament of the ovary proper and the round ligament of the uterus. The latter extends into the labia majora.

The dilated terminal part of the rectum, lying directly above and supported by the pelvic diaphragm (levator ani) and anococcygeal ligament is the ampulla of the rectum.

The synonymous terms vulva and pudendum include the clitoris, vestibule of the vagina, bulbs of vestibule, and greater vestibular gland.

The pubovaginalis, external urethral sphincter, urethrovaginal sphincter, and bulbospongiosus compress the vagina and act like sphincters.

In females, the genital tubercle elongates only slightly and forms the clitoris.

The rapid elongation of the genital tubercle in the male gives rise to the phallus.

Persons with spondylolysis have a defect in the vertebral arch. When this is bilateral, it results in the L5 vertebra being divided into two pieces. If the parts separate, the abnormality is spondylolisthesis, which is anterior displacement of the body of the L5 vertebra on the sacrum.

The urethral folds do not fuse, as in the male, but develop into the labia minora.

The part of the broad ligament forming the mesentery of the uterine tube is the mesosalpinx.

The bladder is relatively free within the extraperitoneal subcutaneous fatty tissue except for its neck, which is held firmly by the puboprostatic ligaments in males and the pubovesical ligaments in females.

In males the rectum is related anteriorly to the fundus of the urinary bladder, terminal parts of the ureters, ductus deferens, seminal vesicles, and prostate.

The ovarian arteries arise from the abdominal aorta.

The slender ducts of the greater vestibular glands pass deep to the bulbs of the vestibule and open into the vestibule on each side of the vaginal orifice. The lesser vestibular glands are small glands on each side of the vestibule that open into it between the urethral and vaginal orifices.

The prostate is the largest accessory gland of the male reproductive system.

The only parts remaining from the mesonephric system are the epoöphoron, paroöphoron, and Gartner’s cyst.

The winglike expansions of the vagina around the end of the uterus, the vaginal fornices, are of paramesonephric origin.

The median umbilical ligament is formed by the remnant of the urachus.

Android and anthropoid pelves are common in males. The platypelloid pelvis is uncommon in both males and females. The gynecoid pelvis is the normal female type of pelvis.

The inferior ends of the seminal vesicles are closely related to the rectum and are separated from it only by the rectovesical septum, a membranous partition.