Chapter 4

Male Sexual Anatomy and Physiology

The Penis

• External anatomy of the penis includes:– Foreskin, glans, shaft, root

Why is it important to conduct regular genital self-exams, and what should a man look for?

The Penis

The Penis

• Internal anatomy of the penis includes:– Cavernous bodies (corpora cavernosa)– Spongy body (corpus spongiosum)– Penile urethra

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 Penis

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 ejaculation

Male Sexual Anatomy during Ejaculation

Concerns about Sexual FunctioningPenis 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– Hygienic value & risk for STI’s question– Medical risks– AAP: moderate opposition

• Data not significant to recommend routine procedure

Male Circumcision

Male Genital HealthPenis Health-Care Issues

• Cleanliness– Smegma– Infections

• Reaction to vaginal secretions

• Injuries

• Penile cancer

Male Genital HealthTesticle 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 HealthProstate Health-Care Issues

• Prostate diseases– Prostatitis

• enlarged and inflamed– Benign prostatic hyperplasia– Prostate cancer

• PSA test

• Treatment options for prostate cancer