chapter 5 male sexual anatomy and physiology

Our Sexuality, 9th Edition, Robert L. CrooksChapter 5: Male Sexual Anatomy and Physiology

Chapter 5

Male Sexual Anatomy and Physiology


Male Sexual Anatomy

• The penis– foreskin, glans, shaft, & root


Male Sexual Anatomy (cont.)

Fig 5.1a Interior structure of the penis: (a) view from above.


• The penis– corpus carvernosa– corpus spongiosum

Fig 5.1b Interior structure of the penis: (b) cross section of the penis



• 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.



• The scrotum– a sac or pouch with two chambers – muscle layer (tunica dartos)

• pulls sac closer to body in cold temperatures– spermatic cord



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.



• The testes – secrete male hormones– produce sperm– cryptorchidism: undescended testis – self-exam is recommended



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.



• The testes– seminiferous tubules

• site of sperm production– interstitial cells

• Major source of androgen– epididymis: sperm maturation



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.



• The vas deferens– moves sperm from scrotum to ejaculatory duct

through prostate– ejaculatory ducts open into the urethra



Fig 5.6 Male sexual anatomy: A cross-section side view of the male reproductive organs.



• The seminal vesicle– secretes 70% of seminal fluid

• The prostate gland– secretes about 30% of seminal fluid– alkaline fluid helps counteract acidity



• The Cowper's glands– attaches to urethra just below prostate– secretes fluid before ejaculation– may contain active, healthy sperm



• Semen (seminal fluid)– about 1 teaspoon– 200 to 500 million sperm



Male Sexual Functions

• Erection – autonomic nervous system

• arteries expand• blood outflow cannot keep up with inflow

tumescence– psychogenic & physiogenic factors


Fig 5.7a Male sexual anatomy during ejaculation: (a) the emission phase.

Male Sexual Functions (cont.)


• Ejaculation– spinal reflex triggers two phases

• emission: fluid in urethral bulb• expulsion: semen expelled

– retrograde ejaculation– nocturnal emission



Fig 5.7b Male sexual anatomy during ejaculation: (b) the expulsion phase.



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)


Concerns About Sexual Functioning (cont.)

• Circumcision– hygienic value & risk for STDs?– medical risks– AAP: moderate opposition

• Phimosis: extremely tight foreskin


Fig 5.9 Circumcision, the surgical removal of the foreskin.

Concerns About Sexual Functioning (cont.)


Male Genital Health Concerns

• Penis health-care issues– cleanliness: smegma, infections– reaction to vaginal secretions – injuries– penile cancer


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


• Prostate health-care issues– prostate diseases

• prostatitis: enlarged & inflamed• benign prostatic hyperplasia• prostate cancer

– PSA test– Treatment options for prostate cancer

Male Genital Health Concerns (cont.)

chapter 5 male sexual anatomy and physiology

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