Atlas of Human Anatomy by Netter

FACTS & HINTS

High-Yield Facts

Anatomic Points

Semen contains:

Sperm from the testes: 40 to 600 million per ejaculate but only 10% of total ejaculate

Seminal vesicle secretions: alkaline fluid rich in fructose, 70% of total ejaculate

Prostatic secretions: lipids, acid phosphatase, proteolytic enzymes, citric acid

Other contents: potassium, zinc, citric acid, phosphorylcholine, spermine, free amino acids, and prostaglandins

Mechanism of Ejaculation

Controlled by sympathetic nervous system

Contraction of smooth muscle of ductus deferens, seminal vesicles, and prostate propels secretions into prostatic urethra

Simultaneous contraction of smooth muscle in bladder neck prevents retrograde ejaculation (reflux of semen into the bladder)

Semen is expelled from the urethra by contraction of the bulbospongiosus muscles

Clinical Points

Hydrocele

An accumulation of serous fluid in space between parietal and visceral layers of tunica vaginalis

Presents as a fluctuant swelling in the testes

Detection requires transillumination-bright light applied to the swelling presents as a red glow in a darkened room

May be congenital, precipitated by trauma or inflammation of the epididymis

Clinical Points

Vasectomy

A method of birth control because it produces sterility

Failure rate less than 95%

Performed under local anesthetic

Vas deferens is isolated via a small scrotal incision in superoanterior scrotal wall

A segment of duct is clamped or ligatured at each end, the segment is sectioned and the ends are cauterised

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Clinical Points

Testicular Cancer

Ninety-five percent are germ cell tumors

Nearly all are malignant

Peak incidence 15 to 34 years

Presents as firm, painless lump in testes or a reactionary varicocele

Potentially curable with surgical resection (orchidectomy) if detected early

Metastasizes to lumbar lymph nodes

Mnemonics

Memory Aids

Table I03-1. Innervation of the Penis

"Point and Shoot" Erection ("Point") is controlled by the Parasympathetic nervous system and ejaculation ("Shoot") by

the Sympathetic nervous system.

"S2, 3, 4 keep the penis off

the floor"

Innervation of the penis by branches of the pudendal nerve, derived from spinal cord levels S2-S4