💡 Learning Outcomes:

1. Identify the parts and joints of the bony pelvis.

2. Identify the locations, parts, microscopic structure, and blood supply of male external genitalia:

   a. Penis, b. Scrotum, c. Distal urethra.

3. Identify the locations, parts, microscopic structure, and blood supply of male internal genitalia:

   a. Testis, b. Epididymis, c. Ductus deferens, d. Ejaculatory ducts, e. Seminal vesicle, f. Prostate.

4. Identify the organization and relationship of these organs with other structures in sagittal section of male pelvis. 

Learning Outcome 1: Identify the parts and joints of the bony pelvis.

Bony Pelvis: The bony pelvis is composed of the following bones and joints:

• Bones:

  

   

  1. Ilium
  2. Ischium
  3. Pubis
  4. Sacrum
  5. Coccyx

• Joints:

  

  • Sacroiliac joint: Joins the sacrum with the ilium on either side.
  • Pubic symphysis: Joins the left and right pubic bones anteriorly.
  • Sacro-coccygeal joint: Between the sacrum and the coccyx.
  • Lumbosacral joint: Between the fifth lumbar vertebra and the sacrum.

• Ligaments:

  

  • Sacrotuberous ligament
  • Sacrospinous ligament
  • Anterior sacroiliac ligament
  • Iliolumbar ligament
  • Anterior longitudinal ligament

• Foramina:

  • Greater sciatic foramen
    • Nerves: Sciatic nerve, superior gluteal nerve, inferior gluteal nerve, pudendal nerve.
  • Lesser sciatic foramen
    • Nerve: Pudendal nerve (supplies muscles of the perineum and external anal sphincter).

Learning Outcome 2: Identify the locations, parts, microscopic structure, and blood supply of male external genitalia (Penis, Scrotum, Distal Urethra).

2a. Penis

• Location: Anterior to the scrotum and perineum, attached to the pubic symphysis by suspensory ligaments.

• Parts:

  • Root: Located in the superficial perineal pouch, consists of two crura and one bulb.
  • Body: Free portion covered by skin. Contains:
    • Corpora Cavernosa (2): Dorsal erectile tissues.
    • Corpus Spongiosum (1): Ventral tissue surrounding the urethra.
  • Glans Penis: Expansion of the corpus spongiosum, distal portion of the penis.

• Microscopic Structure:

  

   

  • Corpora Cavernosa: Composed of erectile tissue and lined by a tunica albuginea.
  • Corpus Spongiosum: Contains the penile urethra and is less tightly surrounded by connective tissue to allow for urethral expansion during ejaculation.

• Blood Supply:

  

  • Arteries: Dorsal artery of the penis, deep artery of the penis (branches of internal pudendal artery).
  • Veins: Superficial and deep dorsal veins draining into the internal pudendal vein.

Mechanism of Erection

• Parasympathetic nerves dilate the deep artery of the penis, increasing blood flow into the cavernous spaces, resulting in erection. Blood is drained through the dorsal veins post-erection.

Circumcision and Phimosis

• Circumcision: Incision of the prepuce, exposing the glans.

• Phimosis: Tight preputial skin that cannot retract over the glans.

2b. Scrotum

• Location: Hangs below the penis in the perineum.

• Parts:
  • Layers: Skin, Dartos fascia, External spermatic fascia, Cremaster muscle and fascia, Internal spermatic fascia, and Tunica vaginalis.

• Microscopic Structure:
  • Dartos Muscle: Smooth muscle responsible for the wrinkled appearance and thermoregulation of the scrotal skin.

• Blood Supply:
  • Arteries: Anterior and posterior scrotal arteries (branches of the external pudendal and internal pudendal arteries, respectively).
  • Veins: Drain into the external pudendal veins.

2c. Distal Urethra

• Location: Runs through the corpus spongiosum and opens at the external urethral meatus at the tip of the glans penis.

• Microscopic Structure:
  • Lined with stratified squamous epithelium near the meatus and pseudostratified columnar epithelium in the spongy part.

• Blood Supply:
  • Arteries: Branches from the internal pudendal artery.
  • Veins: Drain into the deep dorsal vein.

Learning Outcome 3: Identify the locations, parts, microscopic structure, and blood supply of male internal genitalia (Testis, Epididymis, Ductus deferens, Ejaculatory ducts, Seminal vesicle, Prostate).

3a. Testis

• Location: Inside the scrotum, suspended by the spermatic cord. The left testis is usually lower than the right.

• External Features:

  • Poles: Upper and lower poles.
  • Borders: Anterior and posterior.
  • Surfaces: Medial and lateral.
  • Tunica Vaginalis: Double-layered serous covering with parietal and visceral layers.
  • Epididymis: Located on the posterior aspect, separated from the testis by the sinus of epididymis.

• Microscopic Structure:

  

   

   

   

  • Tunica Albuginea: Thick fibrous capsule covering the testis.
  • Seminiferous Tubules: Site of spermatogenesis.
  • Leydig Cells: Found in the interstitial space, responsible for testosterone production.

• Blood Supply:

  • Artery: Testicular artery (branch of the abdominal aorta).
  • Veins: Testicular vein (right drains into the IVC, left into the left renal vein).

3b. Epididymis

• Location: Lies posterior to the testis.

• Parts:

  • Head: Upper end connected to the upper pole of the testis.
  • Body: Middle part separated from the testis by the sinus of epididymis.
  • Tail: Lower end connected to the lower pole of the testis, continues as the ductus deferens.

• Microscopic Structure:

  

  • Duct of Epididymis: Highly coiled tubule with pseudostratified columnar epithelium and stereocilia for absorption and maturation of spermatozoa.

• Blood Supply:

  • Same as the testis.

3c. Ductus Deferens (Vas Deferens)

• Location: Extends from the tail of the epididymis to the ejaculatory duct, passing through the spermatic cord, inguinal canal, and pelvis.

• Microscopic Structure: Thick-walled muscular tube lined by pseudostratified columnar epithelium.

  

• Blood Supply:

  • Artery: Artery to the vas deferens (branch of the superior vesical artery).

• Pathway: Seminiferous tubules → Straight tubules → Rete testis → Efferent Ductules → Epididymis → Vas deferens → Ejaculatory duct → Prostatic urethra.

3d. Ejaculatory Ducts

• Location: Formed by the union of the ductus deferens and seminal vesicle duct. They pass through the prostate and open into the prostatic urethra.

• Blood Supply:
  • From nearby vessels such as the inferior vesical artery.

3e. Seminal Vesicle

• Location: Lies posterior to the bladder and lateral to the ductus deferens.

• Parts: Coiled tubular structure embedded in connective tissue.

• Microscopic Structure: Lined by pseudostratified columnar epithelium.

  

• Function: Secretes fructose-rich fluid, contributing to seminal fluid that forms 70% of semen.

• Blood Supply:

  • Artery: Inferior vesical artery.

3f. Prostate

• Location: Situated below the bladder, anterior to the rectum.

• Parts:

  • Apex: Directed downward, near the external urethral sphincter.
  • Base: Adjacent to the bladder neck.
  • Lobes: Median, lateral, anterior, and posterior lobes.

• Microscopic Structure: Consists of fibromuscular stroma and glandular tissue, including the prostatic glands.

  

   

   

• Blood Supply:

  

  • Arteries: Inferior vesical, middle rectal, and internal pudendal arteries.
  • Veins: Prostatic venous plexus.

• Function: Secretes fluid that forms 15% of semen, aiding in lubrication and neutralizing vaginal acidity.

Learning Outcome 4: Identify the organization and relationship of these organs with other structures in a sagittal section of the male pelvis.

In a sagittal section of the male pelvis:

• Anterior structures: Pubic symphysis, bladder, and the root of the penis.

• Middle structures: Prostate gland, seminal vesicles, and ductus deferens.

• Posterior structures: Rectum and anal canal.

• Relationships:
  • Bladder: Located superior to the prostate and anterior to the seminal vesicles.
  • Prostate: Lies inferior to the bladder and anterior to the rectum. The ejaculatory ducts traverse the prostate and open into the prostatic urethra.
  • Rectum: Situated posterior to the bladder and prostate.