Y2S2 P1 Reproductive Overview

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Questions and Answers

Which structure is considered the articulation point between the sacrum and the final vertebrae?

Pelvic inlet

Pubic symphysis

Ischial tuberosity

Sacral promontory (correct)

What boundaries define the true pelvis?

Pelvic outlet, ileum, and iliac crest

Pelvic inlet, sacrum, and ischium (correct)

Pubic symphysis, sacral promontory, and pelvic outlet

Pelvic inlet, pubic crest, and coccyx

Which ligaments contribute to the stability of the sacroiliac joint?

Lateral and medial ligament of the pelvis

Coccygeal and abdominal ligaments

Iliolumbar and pubic symphysis ligaments

Anterior and posterior sacroiliac ligaments (correct)

Where is the pelvic inlet located in relation to the body?

Superior to the pelvic outlet Signup and view all the answers

Which of the following structures makes up the pelvic floor?

Pelvic outlet muscles Signup and view all the answers

What specifically forms the bony margin of the pelvic inlet?

Formed by specific landmarks including the pubic crest and iliopectineal line Signup and view all the answers

Identify which pelvic cavity region supports the lower abdominal viscera.

Greater pelvis Signup and view all the answers

What characteristic distinguishes the gynaecoid pelvis from the android pelvis?

Short, dull ischial spines Signup and view all the answers

Which pelvis type is characterized as having a kidney-shaped pelvic brim?

Platypelloid Signup and view all the answers

Which of the following features is NOT typical of the male pelvis?

Larger pelvic outlet Signup and view all the answers

In terms of the pelvic outlet, which pelvis type allows for easier childbirth?

Gynaecoid Signup and view all the answers

What is a distinguishing feature of the anthropoid pelvis compared to the gynaecoid pelvis?

Short transversely Signup and view all the answers

Which statement accurately describes the contents of the broad ligament?

It supports both the uterus and the ovaries. Signup and view all the answers

What is the function of the round ligament of the uterus?

To anchor the uterus in an anteverted position. Signup and view all the answers

In what way do the true pelvis viscera differ between males and females?

Females have three midline structures while males have two. Signup and view all the answers

Which component is NOT a substructure of the broad ligament?

Mesotubium Signup and view all the answers

What is the significance of the trigone in relation to the bladder?

It forms the only area of the bladder without detrusor muscle. Signup and view all the answers

Which lymphatic nodes are associated with the drainage of the ovaries?

Para-aortic lymph nodes Signup and view all the answers

What is the most inferior peritoneal pouch in males?

Rectovesical pouch Signup and view all the answers

Which pouch is formed between the bladder and uterus in females?

Vesicouterine pouch Signup and view all the answers

In which position does fluid primarily accumulate in the rectouterine pouch?

Standing position Signup and view all the answers

Which lymphatic nodes are responsible for the drainage of the anal canal inferior to the dentate line?

Superficial inguinal lymph nodes Signup and view all the answers

Which ligament extends from the sacrum to the ischial tuberosity?

Sacrotuberous ligament Signup and view all the answers

What is the primary action associated with the piriformis muscle?

Rotates the thigh laterally Signup and view all the answers

Which of the following muscles is responsible for forming most of the pelvic diaphragm?

Levator ani Signup and view all the answers

How is the coccygeus muscle primarily innervated?

Anterior rami of S2-S4 Signup and view all the answers

Which of the following muscles contributes to the U-shaped sling around the rectal hiatus?

Puborectalis Signup and view all the answers

What is the primary function of the pubic ligaments?

Joining the pubic symphysis Signup and view all the answers

Which muscle is innervated by the pudendal nerve?

Levator ani Signup and view all the answers

What structures separate the true pelvis from the perineum?

Levator ani and coccygeus muscles Signup and view all the answers

Which artery is correctly described as passing through the suprapiriform foramen?

Superior gluteal artery Signup and view all the answers

What is the primary function of the uterine artery in relation to the uterus?

To anastomose with the ovarian artery Signup and view all the answers

Which artery supplies the inferior bladder and also serves the prostate gland in men?

Inferior vesical artery Signup and view all the answers

Where does the ovarian artery originate?

From the abdominal aorta inferior to the renal arteries Signup and view all the answers

Which artery is noted for obliterating to form the medial umbilical ligament?

Umbilical artery Signup and view all the answers

Which artery becomes the superior rectal artery after crossing the pelvic brim?

Inferior mesenteric artery Signup and view all the answers

Which ligament separates the greater and lesser sciatic notches?

Sacrospinous ligament Signup and view all the answers

What structures are transmitted through the obturator canal?

Obturator artery and nerve Signup and view all the answers

Which foramen is divided into suprapiriform and infrapiriform parts by the piriformis muscle?

Greater sciatic foramen Signup and view all the answers

Which vessels enter or exit the pelvis through the lesser sciatic foramen?

Internal pudendal vessels Signup and view all the answers

Which ligament connects the ischial tuberosity to the sacrum?

Sacrotuberous ligament Signup and view all the answers

What key structure is formed by the sacrotuberous and sacrospinous ligaments?

Greater sciatic foramen Signup and view all the answers

Which nerve is responsible for motor innervation to the pelvic floor muscles and sensory innervation to the perineum?

Pudendal nerve Signup and view all the answers

Which portion of the internal iliac artery primarily supplies the pelvic viscera?

Anterior trunk Signup and view all the answers

Which pelvic nerve structure is associated with sympathetic innervation to pelvic vessels and structures?

Sacral splanchnic nerves Signup and view all the answers

Which nerve exits the pelvis via the greater sciatic foramen before reentering through the lesser sciatic foramen?

Pudendal nerve Signup and view all the answers

What function does the inferior hypogastric plexus serve in the autonomic nervous system?

Visceral innervation to pelvic structures Signup and view all the answers

From which spinal levels does the sciatic nerve arise?

L4, L5, S1, S2, S3 Signup and view all the answers

Which of the following statements accurately describes the pelvic splanchnic nerves?

They innervate all pelvic viscera inferior to the splenic flexure. Signup and view all the answers

What is the primary role of the inferior gluteal artery?

Terminating the anterior trunk of the internal iliac artery Signup and view all the answers

What is the role of the Ischiocavernosus muscle in males?

It stabilizes the erect penis and retards blood return. Signup and view all the answers

Which structure in males is primarily involved in secreting seminal fluid?

Bulbourethral glands Signup and view all the answers

How does the role of the external urethral sphincter differ between males and females?

The male external urethral sphincter has both inferior and superior parts. Signup and view all the answers

What are the components of the corpora cavernosa in both males and females?

Sponge-like regions of erectile tissue containing most blood during erection. Signup and view all the answers

What anatomical region is bounded inferiorly by the inferior diaphragmatic fascia?

Deep perineal pouch Signup and view all the answers

What distinction does the labia majora have compared to the scrotum?

It serves as skin covering the external genitals in females. Signup and view all the answers

Which statement accurately reflects the anatomical shape of the female external urethral sphincter?

It does not surround the urethra completely. Signup and view all the answers

What is the primary muscle involved in the stabilization of an erect penis during sexual arousal?

Ischiocavernosus muscle Signup and view all the answers

What structure separates the superficial pouch from the deep pouch in the perineum?

Perineal membrane Signup and view all the answers

Which component of the urogenital triangle is responsible for the transmission of the urethra and vagina?

Urogenital hiatus Signup and view all the answers

Which of the following structures is found in the anal triangle of the perineum?

Rectal hiatus Signup and view all the answers

In males, what structure is indicated as the bulbospongiosus covered area in the superficial perineal pouch?

Root of the penis Signup and view all the answers

What is the primary function of the urogenital diaphragm within the urogenital triangle?

Facilitating the passage of the urethra and vagina Signup and view all the answers

What content is exclusive to the superficial perineal pouch in females?

Greater vestibular glands Signup and view all the answers

Which part of the perineum is primarily responsible for containing the spongy urethra in males?

Superficial perineal pouch Signup and view all the answers

Which anatomical feature separates the perineum into anterior and posterior triangles?

Pelvic outlet Signup and view all the answers

What type of epithelium lines the proximal two-thirds of the urethra?

Transitional epithelium Signup and view all the answers

What anatomical feature contributes to the increased risk of urinary tract infections in females?

Shorter urethra Signup and view all the answers

What anatomical feature is specifically mentioned as part of the male urethra?

Narrowings of the urethra Signup and view all the answers

In which region does rupture of the urethra above the urogenital diaphragm allow urine to be contained?

Rectovesical space Signup and view all the answers

Which sphincter is not anatomically defined in females but is instead functional?

Internal urethral sphincter Signup and view all the answers

What occurs if there is a rupture of Buck's fascia?

Urine will accumulate within Colles' and Scarpa's fascia Signup and view all the answers

Which part of the male urethra is known to be the narrowest?

Membranous urethra Signup and view all the answers

What is the role of the internal anal sphincter?

Maintains contraction through sympathetic stimulation Signup and view all the answers

Where does the anal canal extend from?

From the superior aspect of the pelvic diaphragm to the anus Signup and view all the answers

Which structure marks the widest part of the male urethra?

Navicular fossa Signup and view all the answers

What initiates the contraction of the internal anal sphincter?

Sympathetic stimulation Signup and view all the answers

At which part of the male urethra does the external urethral sphincter reside?

Membranous urethra Signup and view all the answers

What anatomical feature contributes to decreasing the likelihood of urinary tract infections?

Vertical orientation of the urethral lumen Signup and view all the answers

What structures primarily supply the superior and inferior portions of the anal canal?

Superior rectal artery and inferior rectal artery Signup and view all the answers

Which statement accurately describes the drainage of the anal canal above the pectinate line?

Drains to the internal haemorrhoidal plexus. Signup and view all the answers

Which structures are located in the ischioanal fossa?

Internal pudendal artery and inferior rectal nerve Signup and view all the answers

Which of the following best describes the sensitive nerve supply of the anal canal below the pectinate line?

Served by the inferior rectal nerve Signup and view all the answers

What structure demarcates the junction of the endoderm-derived superior anal canal and the ectoderm-derived inferior anal canal?

Pectinate line Signup and view all the answers

Which function does the pudendal canal serve in the pelvic region?

Transmits the inferior rectal nerve and pudendal artery Signup and view all the answers

What is the significance of anal sinuses located above the anal valves?

They exude mucus when compressed. Signup and view all the answers

Which anatomical boundaries define the ischioanal fossa?

Levator ani and gluteus maximus Signup and view all the answers

What type of lymphatic drainage occurs in the anal canal located below the pectinate line?

Drains to superficial inguinal lymph nodes Signup and view all the answers

Which of the following structures is at risk of infection spread in the ischioanal fossa due to its loose connective tissue?

Perforating branches of S2 and S3 Signup and view all the answers

Study Notes

Pelvic Girdle

Formed by two hip bones, connected anteriorly and laterally, with the sacrum posteriorly.
Hip bones are composed of three fused bones:
- Ilium
- Ischium
- Pubis
- All converge at the acetabulum.
Sacrum is the bone that articulates with the hip joint via the sacroiliac joint.
Three ligaments support the sacroiliac joint:
- Anterior sacroiliac ligament
- Posterior sacroiliac ligament
- Interosseous sacroiliac ligament.

Pelvic Cavity

Contains both the abdominal cavity and the pelvic cavity.
Divided into the greater pelvis (false pelvis) and lesser pelvis (true pelvis).
Greater pelvis is superior to the pelvic inlet, housing organs like ileum and sigmoid colon.
Lesser pelvis is inferior to the pelvic inlet, housing pelvic viscera.
Boundaries of the true pelvis:
- Superiorly: Pelvic inlet
- Anteriorly: Pubic symphysis
- Posteriorly: Sacrum and coccyx
- Laterally: Ischium and ilium
- Floor: Pelvic outlet/ pelvic floor muscles.

Pelvic Inlet

Superior most pelvic plane, marking the boundary between the lesser and greater pelvis.
Oblique when standing.
Pelvic brim defines the pelvic inlet, made up of specific landmarks:
- Anteriorly: Pubic crest (pubic symphysis).
- Posteriorly: Sacral promontory (articulation of L5 vertebrae and sacrum).
- Laterally: Iliopectineal line/ linea terminalis (arcuate line of the inner ileum + pectineal line of the superior pubic rami).

Pelvic Outlet

Bounded by:
- Posteriorly: Tip of the coccyx
- Laterally: Ischial tuberosity and sacrotuberous ligament
- Anteriorly: Pubic arch.
Located superior to the pelvic outlet/ floor muscles.

Shapes of the Bony Pelvis

Gynaecoid - This shape, commonly found in women, is characterized by a wide, oval-shaped pelvic inlet, allowing for easy passage of the baby's head during labor. It also boasts a larger pelvic outlet, contributing to an easier childbirth. The ischial spines in this shape are short and less prominent, and the pubic arch is wide, exceeding 90 degrees. This shape accounts for 50% of women.
Android - This type is typically seen in males and shares a heart-shaped pelvic inlet, prominent ischial spines, and a narrow pubic arch. It is more challenging for childbirth, with a narrow, straight, and long pelvic outlet. This shape is found in 25% of women.
Platypelloid - Identified by a kidney-shaped pelvic brim, this type has a shallow pelvic cavity. It is short in the antero-posterior direction but wide transversely.
Anthropoid - This shape is characterized by an oval pelvic brim with a short transverse diameter and a wide antero-posterior dimension.

Male vs. Female Pelvis

Female Pelvis - Wider, broader, and lighter. Oval-shaped pelvic inlet. Larger pelvic outlet. Less prominent ischial spines. Greater subpubic angle. Ligaments are stretchable, including the pubic, sacrotuberous, and sacrospinous ligaments, particularly during pregnancy due to progesterone.
Male Pelvis - Narrower, thicker, and heavier. Heart-shaped pelvic inlet. More narrow pelvic outlet. Prominent ischial spines leading to a lesser bispinous diameter. Smaller subpubic angle. Ligaments are not as stretchable and remain rigid.

Viscera of the True Pelvis

Females have three midline visceral structures within the true pelvis: bladder, uterus, and rectum.
Males have two midline visceral structures: bladder and rectum.
The bladder is a sac-shaped organ formed by the detrusor muscle.
The only section of the bladder without detrusor muscle is the trigone, a triangular patch of smooth muscle..
The ureter and internal urethral orifice are located at the apex of the trigone.
The uterus is the main reproductive organ in females.

Broad Ligament

The broad ligament is a wide double-layer of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis.
It plays a role in maintaining the uterus's position within the pelvic cavity.
The broad ligament has subcomponents: mesometrium, mesosalpinx, and mesovarium.
Mesometrium: mesentery extending laterally from the uterus.
Mesosalpinx: mesentery draping over the fallopian tube
Mesovarium: mesentery draping over the ovaries.

Contents of the Broad Ligament

Reproductive Structures:
- Uterus
- Fallopian tubes
- Ovaries
Vessels:
- Ovarian artery: located within the suspensory ligament.
- Uterine artery: gives rise to the vaginal branch that supplies the inferior vagina.
Ligaments:
- Ovarian ligament: connects the ovary to the lateral part of the uterus. Extends from the ovary to the fundus of the uterus.
- Round ligament of the uterus: a remnant of the gubernaculum. It helps to keep the uterus in an anteverted position, flexed over the bladder. It extends from the uterus to the labia majora via the inguinal canal.
- Suspensory ligament of the ovary: houses the ovarian artery, vein, and lymphatics. Extends from the mesovarium to the pelvic wall.

Lymphatic Drainage of Pelvic Viscera

The testes and ovaries drain to the para-aortic lymph nodes.
The superior rectum and sigmoid colon drain to the pararectal and inferior mesenteric lymph nodes.
The scrotum, perianal skin, anal canal inferior to the dentate line, skin of the perineum and round ligament drain to the superficial inguinal lymph nodes.

Pouches of the Abdominal Viscera

Peritoneal coverings on the surface of viscera form pouches.
Females have two pouches, while males only have one.
The rectovesical pouch is the most inferior part of the peritoneal cavity in males, located between the rectum and bladder.
The rectouterine pouch (also known as the Pouch of Douglas) is the most inferior part of the peritoneal cavity in females, located between the rectum and uterus. Fluid accumulates here in the erect position.
The vesicouterine pouch is located between the bladder and uterus in females.

Ligaments of the Pelvis

Sacroiliac ligaments secure the sacroiliac joint.
- Anterior sacroiliac ligament
- Posterior sacroiliac ligament
- Interosseous sacroiliac ligament
Pubic ligaments join the pubic symphysis.
- Superior pubic ligament
- Inferior pubic ligament
Sacrospinous ligament extends from the sacrum to the ischial spine.
Sacrotuberous ligament extends from the sacrum to the ischial tuberosity.

Muscles of the Pelvic Wall and Floor

Boundary	Muscle	Attachments	Innervation	Action
Lateral wall	Obturator internus	Pelvic surfaces of ileum, ischium and obturator membrane → greater trochanter	Nerve to obturator internus (L5, S1, S2)	Rotates thigh laterally
Postero-superior wall	Piriformis	S2-S4 vertebrae → superior margin of greater sciatic notch and sacrotuberous ligament	Anterior rami of S1 and S2	Rotates thigh laterally
Floor	Coccygeus	Ischial spine → inferior end of coccyx	S4 and S5	Flexes coccyx
Floor	Levator ani (pubococcygeus, iliococcygeus, puborectalis, pubvaginalis)	Body of pubis, tendinous arch of obturator fascia and ischial spine → perineal body, coccyx, anococcygeal ligament	Pudendal nerve (S2, S3, S4) and anterior rami of S4	Forms most of the pelvic diaphragm which supports the pelvic viscera and resists increases in intra-abdominal pressure

Pelvic Diaphragm

The pelvic floor/diaphragm is a bowl-shaped structure composed of muscle fibers of the levator ani and the coccygeus muscles (and associated connective tissue).
Separates the true pelvis superiorly from the perineum inferiorly.

Levator Ani and Coccygeus

Puborectalis
- U-shaped sling extending from pubic bone → pubic bone around the rectal hiatus (which transmits the anal canal).
- Contraction bends the anal canal.

Somatic Nerves of Pelvis

Most nerves of the pelvis are formed from the sacral plexus, except for the femoral nerve (L2, L3, L4), which supplies the anterior thigh.
The sacral plexus is located posterior to the arteries and veins that supply the pelvic viscera.
The Sciatic nerve (L4, L5, S1, S2, S3) is the largest nerve in the body, providing innervation to the posterior thigh muscles and sensory input for most of the leg and foot.
The Pudendal Nerve (S2, S3, S4) leaves the pelvis through the greater sciatic foramen, re-enters through the lesser sciatic foramen and courses through the pudendal canal.
- Innervates the pelvic floor muscles, external anal and urethral sphincters, and provides sensory innervation to the perineum.
The Obturator Nerve (L2, L3, L4) leaves the pelvis through the obturator canal, providing motor and sensory innervation to the medial thigh.

Autonomic Nerves of the Pelvis

Formed from the plexus of sacral splanchnic nerves (SNS) and pelvic splanchnic nerves (PNS).
Sympathetic fibers are carried by sacral splanchnic nerves (S2-S4), which innervate pelvic vessels and structures.
Parasympathetic fibers are carried by pelvic splanchnic nerves (S2-S4), which innervate all viscera inferior to the splenic flexure (viscera superior to the splenic flexure are innervated by the vagus nerve).
The inferior hypogastric plexus gives rise to the prostatic plexus, uterovaginal plexus and vaginal plexuses.

Vasculature of the Pelvis

Most of the vascular supply to the pelvis originates from the internal iliac artery and its branches.
The bifurcation of the aorta occurs at L4.
The bifurcation of the common iliac artery occurs at L5/S1.
The internal iliac artery crosses the pelvic inlet and divides into anterior and posterior branches at the superior aspect of the greater sciatic foramen.

Anterior Trunk

Supplies the walls, viscera and bladder.
- Walls:
  - The Internal pudendal artery leaves and re-enters the pelvis via the greater and lesser sciatic foramens respectively, to supply the perineum.
  - The Inferior gluteal artery, a terminal branch of the anterior trunk, supplies the gluteus maximus muscle and passes through the infrapiriform foramen.
  - The Obturator artery travels through the obturator canal.
- Viscera:
  - The Vaginal artery supplies the vagina, inferior bladder, and rectum in women.
  - The Uterine artery descends along the lateral aspect of the uterus and anastomoses with the ovarian artery, supplying the uterus. It courses superior to the ureter ('water under the bridge').
  - The Middle rectal artery supplies the distal rectum, anastomosing with the other rectal arteries.
- Bladder:
  - The Umbilical artery obliterates to form the medial umbilical ligament.
  - The Superior vesical artery supplies the superior bladder, sometimes a branch of the umbilical artery.
  - The Inferior vesical artery supplies the inferior bladder and the prostate gland and seminal vesicles in men.

Posterior Trunk

The posterior trunk has three branches:
- Iliolumbar arteries:
  - The Lumbar branch supplies the posterior abdominal wall and psoas major.
  - The Iliac branch supplies the iliac fossa (iliac fossa connects to iliac crest).
- Lateral sacral arteries.
- Superior gluteal artery (terminal branch of the posterior trunk), supplies the gluteus medius and minimus muscles. It passes through the suprapiriform foramen.

Ovarian Artery

Arises from the abdominal aorta, inferior to the renal arteries and superior to the IMA.
Crosses the brim and the origin of the external iliac vessels.
Travels down the suspensory ligament of the ovary, enters the mesovarium to anastomose with the uterine artery in the broad ligament.
Divides into ovarian branches and tubal branches.

Pelvic Regions

The pelvic brim is the bony edge of the pelvic inlet:
Anteriorly = pubic crest
Laterally = iliopectineal line
Posteriorly = sacral promontory
Vessels crossing the pelvic brim include:
- Ovarian vessels.
- Vessels of the sigmoid mesentery:
  - Inferior mesenteric artery (becomes superior rectal artery after crossing the pelvic brim).
  - Superior rectal artery.
  - Median sacral artery.

Ligaments

Anterior and posterior sacroiliac ligaments: join the joint ala and sacrum.
Sacrospinous ligaments: join the ischial spine and sacrum.
- Separate the greater and lesser sciatic notch.
Sacrotuberous ligaments: join the ischial tuberosity and sacrum.
- Close the greater sciatic notch → greater sciatic foramen.
- Close the lesser sciatic notch → lesser sciatic foramen.

Greater Sciatic Foramen

Formed by the sacrotuberous ligament and sacrospinous ligament.
The piriformis muscle passes through the greater sciatic foramen, dividing it into:
- Suprapiriform foramen: superior gluteal nerve, artery, and vein.
- Infrapiriform foramen: inferior gluteal nerve, artery, and vein, sciatic nerve, pudendal nerve (upon leaving the pelvis), internal pudendal artery, and vein (upon leaving the pelvis).

Lesser Sciatic Foramen

Formed by the sacrotuberous ligament and sacrospinous ligament.
Contents
- Obturator internus muscle.
- Pudendal nerve (upon re-entering the pelvis).
- Internal pudendal vessels (upon re-entering the pelvis).

Sciatic Foramen Structures

Suprapiriform foramen: superior gluteal nerve, artery, vein.
Infrapiriform foramen: inferior gluteal nerve, artery, vein, sciatic nerve, pudendal nerve, internal pudendal artery and vein, nerve to obturator internus, nerve to quadratus femoris, posterior femoral cutaneous nerve.

Lesser Sciatic Foramen Structures

Exiting the pelvis: obturator internus muscle.
Entering the pelvis: internal pudendal artery, vein, pudendal nerve, nerve to obturator internus.

Obturator Foramen

Large opening in the ischium and pubi.
A strong membrane is attached to the margin (obturator membrane).
site of attachment of the obturator internus and externus muscles.
Contains the obturator canal that transmits:
- Obturator artery.
- Obturator nerve.

Perineum Overview

Shallow compartment located at the pelvic outlet
Separated from the pelvic cavity by the diaphragmatic fascia
Diamond-shaped structure divided into anterior and posterior triangles

Urogenital Triangle

Anterior triangle
Covered by the urogenital diaphragm
Bounded by the perineal membrane
Contains the urogenital hiatus which transmits the urethra and vagina
The perineal membrane divides the superficial and deep pouches

Anal Triangle

Posterior triangle
Contains the rectal hiatus which transmits the anal canal
Surrounded by the ischioanal fossae

Superficial Perineal Pouch

Located between the superficial fascia and the perineal membrane
Bounded laterally by the ischiopubic rami
Contains:
- Root of the penis and associated muscles in males (bulbospongiosus and ischiocavernosus)
- Clitoris and associated muscles in females (ischiocavernosus)
- Proximal part of the spongy urethra in males
- Bulbs of the vestibule and surrounding muscle in females (bulbospongiosus)
- Greater vestibular glands in females
- Superficial transvers perineal muscles
- Deep perineal branches of the internal pudendal vessels and pudendal nerves

Male and Female Genitalia

Corpus Spongiosum and Glans Penis (Male) / Glans Clitoris (Female)

Distal end of spongy erectile tissue
Contains the spongy urethra in males

Bulb of the Penis (Male) / Vestibular Bulb (Female)

2 elongated masses of spongy erectile tissue lateral to the proximal urethra
Engorge with blood during arousal, contributing to erection
Covered by the bulbospongiosus muscle

Crus of the Penis (Male) / Crus of Clitoris (Female)

Distal extension of the corpora cavernosa
Located laterally to the bulb of the penis/vestibular bulb
Consists of erectile tissue
Covered by the ischiocavernosus muscle
Helps flex the anus
Stabilizes the erect penis/tenses the vagina in orgasm
Pelvic floor exercises can tone this muscle

Corpora Cavernosa Penis (Male) / Corpora Cavernosa Clitoris (Female)

Sponge-like regions of erectile tissue
Contains most of the blood during erections

Bulbourethral Glands (Male) / Greater Vestibular Glands (Female)

Secrete lubricating mucous (females) and seminal fluid (males)

Urethral Meatus (Male/Female)

External opening of the urethra/external urethral orifice

Scrotum (Male)/ Labia Majora (Female)

Skin covering external genitals

Deep Perineal Pouch

Located between the inferior and superior diaphragmatic fascia
Contains:
- Urogenital diaphragm: triangular muscle containing the external urethral sphincter

Male External Urethral Sphincter

Only the inferior part encloses the urethra
Superior part invests the prostatic urethra
Trough-like fibers ascend to the neck of the bladder

Female External Urethral Sphincter

Not trough-shaped

Urethra

The urethra is the tube that carries urine from the bladder to the outside of the body.
It begins at the apex of the trigone of the bladder (internal urethral orifice).
The proximal ⅔ of the urethra is lined with transitional epithelium, while the distal ⅓ is lined with stratified squamous epithelium.

Female Urethra

The female urethra is about 4-5 cm long.
It exits the body between the clitoris and the vagina.
It travels obliquely downward and forward.
The female urethra has only one anatomical sphincter, the urethral sphincter, which is made up of the bladder neck and proximal urethra, and is functionally rather than anatomically distinct.
The urethral sphincter is innervated by the pudendal nerve and controls voluntary urination.
The short length of the female urethra can increase risk of urinary tract infections.

Male Urethra

The male urethra is about 20 cm long.
It has two sphincters: the internal urethral sphincter and the external urethral sphincter.
The male urethra is also responsible for ejaculation of semen.
The male urethra is divided into four sections:
- Pre-prostatic (intramural) urethra: Located at the internal urethral orifice and contains the internal urethral sphincter which prevents semen from entering the bladder.
- Prostatic urethra: Passes through the prostate gland, and the ejaculatory duct joins here (ductus deferens and seminal glands).
- Membranous urethra: Located at the level of the urogenital diaphragm and contains the external urethral sphincter. It is the narrowest part of the urethra.
- Spongy (penile) urethra: Contained within the corpus spongiosum. This section is divided into 2 curves: the infrapubic angle and the prepubic angle.
The external urethral orifice is the opening at the end of the penis.

Rupture of the Urethra

Rupture of the urethra above the urogenital diaphragm will result in urine being contained by the levator ani within the pelvis (rectovesical space).
Rupture of the urethra below the perineal membrane (e.g. at the spongy urethra):
- If Buck’s fascia is not ruptured, urine will accumulate within it.
- If Buck’s fascia is ruptured, urine will accumulate within Colles’ and Scarpa’s fascia.