repro anatomy

What is the pelvic cavity?

A hollow, funnel-shaped space within the pelvic girdle containing terminal parts of the digestive tract, parts of the urinary and reproductive systems, and associated neurovascular structures.

What are the two main divisions of the pelvic cavity?

Greater (false) pelvis and lesser (true) pelvis.

Where is the greater (false) pelvis located?

Above the pelvic inlet, within the iliac fossae.

Is the greater pelvis structurally part of the pelvic cavity?

No, it's part of the abdominal cavity.

What does the greater pelvis support?

Abdominal contents like the sigmoid colon and ileum.

Where is the lesser (true) pelvis located?

Below the pelvic inlet, enclosed by the bony pelvis.

What does the lesser pelvis contain?

Pelvic viscera: urinary bladder, rectum, prostate and seminal vesicles in males.

What defines the pelvic inlet?

The boundary between the greater and lesser pelvis.

What forms the posterior part of the pelvic inlet?

Promontory and ala of the sacrum.

What forms the lateral part of the pelvic inlet?

Arcuate line of the ilium and pecten pubis (superior pubic ramus).

What forms the anterior part of the pelvic inlet?

Pubic crest.

What is the linea terminalis?

The combined bony landmarks forming the pelvic brim.

What does the linea terminalis outline?

The pelvic brim, or the entrance to the true pelvis.

What defines the pelvic outlet?

The exit of the true pelvis into the perineum.

What bounds the pelvic outlet anteriorly?

Pubic symphysis.

What bounds the pelvic outlet laterally?

Ischiopubic rami, ischial tuberosities, sacrotuberous ligaments.

What bounds the pelvic outlet posteriorly?

Coccyx.

What is the orientation of the pelvic cavity?

Posteroinferiorly — inlet faces forward, outlet faces slightly backward.

What structures help enclose and support the pelvic cavity?

Ligaments and muscles.

Where does the sacrospinous ligament run?

From sacrum to ischial spine.

Where does the sacrotuberous ligament run?

From sacrum to ischial tuberosity.

What does the obturator membrane cover?

The obturator foramen (except the obturator canal).

What muscle covers the inner surface of the obturator foramen?

Obturator internus.

What muscle exits the pelvis through the greater sciatic foramen?

Piriformis.

Where does the piriformis muscle attach?

To the femur.

What is the superior boundary of the pelvic cavity?

Parietal peritoneum.

What is the inferior boundary of the pelvic cavity?

The pelvic diaphragm.

What is the pelvic diaphragm?

A funnel-shaped muscular floor supporting the pelvic organs.

What muscles make up the pelvic diaphragm?

Levator ani (main) and coccygeus (posteriorly).

What does the pelvic diaphragm do?

Seals the inferior pelvic outlet and supports pelvic organs.

Where is the perineum located?

Below the pelvic diaphragm, bounded by the pelvic outlet.

What shape is the perineum?

Diamond-shaped.

How is the perineum divided?

Into urogenital and anal triangles.

What are the boundaries of the urogenital triangle?

Pubic symphysis to ischial tuberosities.

What does the urogenital triangle contain?

Urethra and external genitalia.

What are the boundaries of the anal triangle?

Ischial tuberosities to coccyx.

What does the anal triangle contain?

Anal canal and anal sphincter.

What openings exist in the pelvic diaphragm?

For urethra, vagina (in females), and anal canal.

Why is the urogenital diaphragm needed?

To provide support beneath the pelvic diaphragm hiatuses.

What is the urogenital diaphragm?

Deep perineal muscles forming the deep perineal pouch.

What covers the urogenital diaphragm?

The perineal membrane and superior fascia of the urogenital diaphragm.

What is the perineal membrane made of?

Thick connective tissue.

Where does the perineal membrane anchor?

To the ischiopubic rami.

What openings does the perineal membrane have?

For urethra and vagina (in females).

What does the perineal membrane support?

External genitalia attachment.

What muscles are in the deep perineal pouch?

External urethral sphincter and deep transverse perineal muscle.

What is the function of the external urethral sphincter?

Surrounds and controls the urethra.

What is the function of the deep transverse perineal muscle?

Stabilizes the perineal body.

What does the anterior (urogenital) part of the perineum contain?

Urogenital diaphragm and external genitalia.

What does the posterior (anal) part of the perineum contain?

Anal canal and external anal sphincter.

Where do the testes develop embryologically?

In the posterior abdominal wall near the L2 vertebral level.

What structure is near the developing testes?

The mesonephros (primitive kidney).

How do the testes reach the scrotum?

They descend through the inguinal canal during fetal development.

What structures do the testes pull with them during descent?

Vessels, nerves, and ducts — forming the spermatic cord.

What is the processus vaginalis?

An embryonic diverticulum of the peritoneum that descends with the testes.

What does the processus vaginalis contribute to?

The peritoneal covering of the testes.

What happens to the processus vaginalis after descent?

It normally obliterates.

What structure remains after the processus vaginalis obliterates?

The tunica vaginalis.

What type of membrane is the tunica vaginalis?

A double-layered serous membrane.

What other membranes is the tunica vaginalis similar to?

Pleura and pericardium.

What does the visceral layer of the tunica vaginalis cover?

The surface of the testes.

What does the parietal layer of the tunica vaginalis line?

The inner wall of the scrotum.

What is found between the layers of the tunica vaginalis?

A thin lubricating fluid to reduce friction during testicular movement.

What causes a hydrocele?

Partial persistence of the processus vaginalis.

What is the result of a hydrocele?

Fluid accumulation between layers of tunica vaginalis.

What causes an inguinal hernia related to the tunica vaginalis?

A patent processus vaginalis that remains open.

What is the result of an inguinal hernia in this context?

Herniation of intestines into the inguinal canal, possibly with a hydrocele.

What is the tunica albuginea?

A thick, white fibrous capsule deep to the tunica vaginalis.

What does the tunica albuginea do?

Encloses the testis and sends septa into it, dividing it into lobules.

What does the posterior thickening of the tunica albuginea form?

The mediastinum testis.

What enters and exits the testis at the mediastinum testis?

Blood vessels, lymphatics, and ducts.

Where are seminiferous tubules located?

Within each lobule of the testis.

What are seminiferous tubules derived from?

The sex cords of the germinal epithelium.

What is the function of seminiferous tubules?

Sperm production (site of spermatogenesis).

What do seminiferous tubules connect to as they mature?

A network of straight tubules called the rete testis.

Where is the rete testis located?

Within the mediastinum testis.

What are efferent ductules?

Small ducts that arise from the rete testis and exit into the epididymis.

What is the epididymis derived from?

The mesonephric (Wolffian) duct.

Where is the epididymis located?

Posterior to the testis.

What are the functions of the epididymis?

Store sperm, mature sperm, and propel sperm during ejaculation.

How does the epididymis propel sperm?

By muscular contraction.

What is the ductus (vas) deferens?

A continuation of the epididymis.

What type of structure is the vas deferens?

A thick-walled muscular tube.

Where does the vas deferens ascend?

In the spermatic cord, through the inguinal canal into the pelvis.

What does the vas deferens merge with?

The duct of the seminal vesicle.

What does the vas deferens and seminal vesicle duct form?

The ejaculatory duct.

Where does the ejaculatory duct pass through?

The prostate.

Where does the ejaculatory duct open into?

The prostatic urethra.

What is the final function of the ejaculatory duct?

To mix sperm with seminal fluid and deliver it to the urethra.

What is the embryological origin of the vas deferens?

Mesonephric (Wolffian) duct.

What does the mesonephric duct originally open into?

The cloaca.

What is the cloaca?

The embryonic precursor to the hindgut and urogenital structures.

What happens to the distal mesonephric duct during development?

It becomes incorporated into the posterior bladder wall.

What structure does this form?

The trigone of the bladder.

What is the embryological origin of the bladder trigone?

Mesoderm (from mesonephric duct incorporation).

What is the embryological origin of the rest of the bladder epithelium?

Endoderm (from urogenital sinus).

Where do the ureteric openings appear?

At the lateral angles of the trigone.

Where do the ejaculatory ducts open?

Near the midline of the prostatic urethra.

What is the embryological origin of the seminiferous tubules?

Germinal epithelium (sex cords).

What is the embryological origin of the epididymis?

Mesonephric (Wolffian) duct.