Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Chapter 5
Male Sexual Anatomy and Physiology
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy
• The penis
– foreskin, glans, shaft, & root
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
Fig 5.1a Interior structure of the penis: (a) view from above.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The penis
– corpus carvernosa
– corpus spongiosum
Fig 5.1b Interior structure of the penis: (b) cross section of the penis
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The penis; corona, frenulum
Fig 5.2 This figure, a view of the underside of the penis, shows the location of the
corona and frenulum—two areas on the penis that harbor a high concentration of
sensitive nerve endings.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The scrotum
– a sac or pouch with two chambers
– muscle layer (tunica dartos)
• pulls sac closer to body in cold temperatures
– spermatic cord
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
Fig 5.3 The scrotum and the testes. The spermatic cord can be located by palpating
the scrotal sac above either testicle with thumb and forefinger.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The testes
– secrete male hormones
– produce sperm
– cryptorchidism: undescended testis
– self-exam is recommended
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
Fig 5.4 Underlying structures of the scrotum. This illustration shows portions of the
scrotum cut away to reveal the cremasteric muscle, spermatic cord, vas deferens, and
a testis within the scrotal sac.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The testes
– seminiferous tubules
• site of sperm production
– interstitial cells
• Major source of androgen
– epididymis: sperm maturation
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
Fig 5.5a Internal structure of a testis. Sperm are produced in the seminiferous tubules
and transported to the epididymis, which serves as a storage chamber.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The vas deferens
– moves sperm from scrotum to ejaculatory duct
through prostate
– ejaculatory ducts open into the urethra
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
Fig 5.6 Male sexual anatomy: A cross-section side view of the male reproductive
organs.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The seminal vesicle
– secretes 70% of seminal fluid
• The prostate gland
– secretes about 30% of seminal fluid
– alkaline fluid helps counteract acidity
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• The Cowper's glands
– attaches to urethra just below prostate
– secretes fluid before ejaculation
– may contain active, healthy sperm
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Anatomy (cont.)
• Semen (seminal fluid)
– about 1 teaspoon
– 200 to 500 million sperm
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Functions
• Erection
– autonomic nervous system
• arteries expand
• blood outflow cannot keep up with inflow 
tumescence
– psychogenic & physiogenic factors
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Functions (cont.)
Fig 5.7a Male sexual anatomy during ejaculation: (a) the emission phase.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Functions (cont.)
• Ejaculation
– spinal reflex triggers two phases
• emission: fluid in urethral bulb
• expulsion: semen expelled
– retrograde ejaculation
– nocturnal emission
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Sexual Functions (cont.)
Fig 5.7b Male sexual anatomy during ejaculation: (b) the expulsion phase.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Concerns About Sexual Functioning
• Penis size
– symbol of virility
– erect penises show less variation than flaccid
– size not related to sexual satisfaction
– penile augmentation
– genital retraction syndrome (koro)
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Concerns About Sexual Functioning (cont.)
• Circumcision
– hygienic value & risk for STDs?
– medical risks
– AAP: moderate opposition
• Phimosis: extremely tight foreskin
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Concerns About Sexual Functioning (cont.)
Fig 5.9 Circumcision, the surgical removal of the foreskin.
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Genital Health Concerns
• Penis health-care issues
– cleanliness: smegma, infections
– reaction to vaginal secretions
– injuries
– penile cancer
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Genital Health Concerns (cont.)
• Testicle health-care issues
– testicular cancer
• rare, but more common in young men (15 to 34
years)
• sign: hard or irregular mass
• Survival > 90% if detected early
Our Sexuality, 9th Edition, Robert L. Crooks
Chapter 5: Male Sexual Anatomy and Physiology
Male Genital Health Concerns (cont.)
• Prostate health-care issues
– prostate diseases
• prostatitis: enlarged & inflamed
• benign prostatic hyperplasia
• prostate cancer
– PSA test
– Treatment options for prostate cancer