1. Male Sexual Anatomy,
Physiology and Behaviour
Andre Sookdar
Class of 2013

2. Objectives
• Anatomy – External and Internal
• Physiology and Behaviour

3. External Anatomy
Penis
• Male Sexual Organ for intercourse
• Pathway for Semen and Urine
• Corpus Cavernosum – spongy tissue
that engorge with blood, stiffening penis
• Corpus Spongiosum – contains urethra,
runs along the length, ending and
dilating to form Glans

4. External Anatomy
• Root – Base of the penis
• Shaft – Body of penis, which expands
on excitation
• Foreskin – Loose collection of skin
covering the Glans
Skin is attached just proximal to the
head on the shaft
Circumcision may be done based on
choice, religion or culture.

6. External Anatomy
• Glans – Highly sensitive tip
• Corona – rim that separates the Glans
from the shaft
• Frenulum – strip of tissue connecting
the glans to the shaft

7. External Anatomy
Scrotum
• Pouch containing the testes
• Provides the ideal temperature for
spermatogenesis (2 degrees lower)
• Left testis usually lower than right
• Size, shape and surface area changed
by Dartos muscle

8. Internal Anatomy
Testes
• Suspended in scrotum by spermatic
cord
• Produces sperm and male sex
hormones
• Highly innervated and sensitive
• Moved by Cremasteric muscle

9. Internal Anatomy
• LH Stimulation of
Testosterone
secretion by
Leydig interstitial
cells
• FSH regulation of
sperm production
• Negative feedback

10. Internal Anatomy
• Epididymis – lie against the back side
of the testis and stores sperm
• Vas Deferens – tube that connects the
epididymis to the ejaculatory duct
• Seminal Vesicles – small glands
beneath the bladder that secrete
seminal fluid

11. Internal Anatomy
• Prostate Gland – walnut sized gland
that secretes prostatic fluid.
• Cowper’s Gland (Bulbouretheral
Glands) – pea-sized glands at the base
of the penis below the prostate that
secrete fluid during sexual arousal

12. Male Anatomy

13. Semen
• 70% from seminal vesicles, 1% sperm,
the rest from the Prostate and
Cowper’s gland
• Typically has 200-400 million per
ejaculate
• Over 15 million per ml is normal
• Other parameters include motility,
morphology and volume.

14. Sexual Function
• Erection
• Emission
• Expulsion

17. Erection
• Engorgement of the penis with blood
• Affected by physical and psychological
factors
• Possible throughout the entire lifespan
• During REM sleep
• Stimulation may be from sensation via
the pudendal nerve or psychological
stimuli via the limbic system

18. Erection
• Parasympathetic response to stimulation
exits the spinal cord at S2-4 and reaches the
penis via Nervi Erigentes
• These are believed to release nitric oxide and
vasoactive intestinal peptide in addition to
acetylcholine
• Results in relaxation of the penile arteries,
hence vasodilation and expansion of the
penis
• Parasympathetic impulses also stimulate the
urethral and Cowper’s glands.

19. Emission
• Sympathetic impulses from T12 to L2
travel via hypogastric and pelvis nerve
plexuses to initiate emission
• Contraction of vas deferens and ampulla,
expelling sperm in to the internal urethra.
• Followed by contraction and fluid addition
by the prostate, seminal vesicles and
Cowper’s glands
• This is now semen and the formation of
this in the internal urethra is emission

20. Journey of the Sperm

21. Expulsion
• Expulsion or ejaculation
• Filling of the internal urethra stimulates the
pudendal nerve contractions of the genital
organs, the ischiocavernosus and
bulbocavernosus muscles  expulsion of semen
• The external urethral sphincter relaxes while
Internal urethral sphincter contracts to prevent
retrrograde ejaculation
• This may be accompanied by movement of the
pelvic and trunk muscles
• Emission and ejaculation together make up the
male orgasm, which lasts 1-2 minutes

22. Case 1
• A patient presents with the request to
enlarge his penis….

23. Penis Enlargement
• Many cultures are obsessed with penis
size
• No medication or device has ever been
approved for penis enlargement
• Stretching & Squeezing
• Penile Weights
• Vacuum Pumps
• Pills and lotions

24. Surgical Enlargement
• Lengthened by cutting the
suspensory ligament that
attaches penis to pubic bone
• Thickened by injecting body
fat from another area
• Cosmetic, not medically
indicated, safety an issue

25. Case 2
• 19 yo man presents with
bumps on the glans and
corona of his penis. He
says he has had it as long
as he can remember.

26. Pearly Penile Papules
• Benign lesion, not genital warts or HSV
• Unknown etiology
• Occurs more in uncircumcised
• Requires no treatment

27. Conclusion
• Anatomy
• Physiology
• Sexual cycle

28. THANK YOU

29. References
1. Allyn, Bacon [Internet] 2008
Available from :
spot.pcc.edu/~gtinker/PSY_231/Chapter
%204.ppt
2. Moore, KL. Clinically Oriented Anatomy
3rd Ed. Williams and Wilkins 1992
3. Guyton, Hall. Textbook of Medical
Physiology 12th Ed. Saunders 2010