Chapter 4
Male Sexual Anatomy and Physiology
The Penis
• External anatomy of the penis includes:
– Foreskin, glans, shaft, root
• Internal anatomy of the penis includes:
– Cavernous bodies (corpora cavernosa)
– Spongy body (corpus spongiosum)
– Penile urethra
Why is it important to conduct regular genital self-exams, and what should a man
look for?
The Penis
The Penis
• Corona
• Frenulum
• Glans
The Penis
The Scrotum
• Sac or pouch with two chambers
• Muscle layer (tunica dartos)
– Pulls sac closer to body in cold temperatures
• Spermatic cord
The Testes
• Testes
– Secrete male hormones
– Produce sperm
• Cryptorchidism
– Undescended testis
• Self-exam is recommended
Underlying Structures of the Scrotum
The Testes
• Seminiferous tubules
– Site of sperm production
• Interstitial cells
– Major source of androgens
• Epididymis
– Sperm maturation
Internal Structure of a Testis
The Vas Deferens
• Move sperm from scrotum to ejaculatory duct
through prostate
• Ejaculatory ducts open into the urethra
Male Sexual Anatomy
Male Sexual Anatomy
• Seminal Vesicle
– Secretes 70% of seminal fluid
• Prostate Gland
– Secretes 30% of seminal fluid
• Cowper’s Glands
– Secretes fluid before ejaculations
– May contain active, healthy sperm
• Semen (seminal fluid)
– Volume is about 1 teaspoon
– 200 to 500 million sperm
Erection
• Coordinated by autonomic nervous system
– Arteries expand
– Blood out flow cannot keep up with in flow
• Capacity for erection is present at birth
• Psychogenic and physiogenic erections
Ejaculation
• Spinal reflex triggers two phases
– Emission
• Fluid in urethral bulb
– Expulsion
• Semen expelled
• Retrograde ejaculation
• Nocturnal emission
Concerns about Sexual Functioning
Penis Size
• Penis size is seen as a symbol of virility
• Erect penises show less variation than flaccid
• Size NOT related to sexual satisfaction
• Penile augmentation
• Genital retraction syndrome
Concerns about Sexual Functioning
• Phimosis
– Extremely tight foreskin
• Circumcision
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Hygienic value & risk for STI’s question
Medical risks
Some states are trying to ban circumcision
AAP: moderate opposition
• Data not significant to recommend routine procedure
Male Genital Health
Penis Health-Care Issues
• Cleanliness
– Smegma
– Infections
• Reaction to vaginal secretions
• Injuries
• Penile cancer
Male Genital Health
Testicle Health-Care Issues
• Testicular Cancer
– More common in young men (20 to 35 years old)
– Risk factors
– Hard or irregular mass in testes
– Survival is greater than 90% if detected early
Male Genital Health
Prostate Health-Care Issues
• Prostate diseases
– Prostatitis
• enlarged and inflamed
– Benign prostatic hyperplasia
– Prostate cancer
• New guidelines from the USPSTF
– Healthy men should not have the PSA test
• Treatment options for prostate cancer