31.6
ペニス
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Q1: What are the three main regions of the penis?
The penis has three primary regions: the glans penis (the enlarged tip surrounding the external urethral orifice), the body (the elongated shaft containing erectile tissue), and the root (the proximal end anchoring the penis to the pelvis). Each region has distinct anatomical features and functions essential for reproduction and urination.
Q2: What is the function of the corpus spongiosum?
The corpus spongiosum is the smaller midventral mass of erectile tissue that surrounds the urethra, ensuring it remains open during ejaculation for semen passage. The expanded proximal end of the corpus spongiosum forms the bulb of the penis, which anchors the organ to the pelvis as part of the root.
Q3: How do the corpora cavernosa contribute to penile erection?
The corpora cavernosa are paired dorsolateral masses of erectile tissue that fill with blood during sexual arousal, causing the penis to become rigid and erect. These tissues are enveloped by tunica albuginea and are primarily responsible for the mechanical aspects of male sexual response erection and ejaculation.
Q4: What is the prepuce and what does it cover?
The prepuce, or foreskin, is loose skin that covers the glans penis and extends distally along the head. It protects the sensitive glans and plays a role in sexual pleasure. The glans itself houses the external urethral orifice, the exit point for both urine and semen.
Q5: What structures make up the root of the penis?
The root of the penis comprises the bulb and the crura, which together anchor the penis to the pelvis. The bulb is the expanded proximal end of the corpus spongiosum, while the crura are the separated and tapered portions of the corpora cavernosa. These structures provide essential stability and support.
Q6: What role does the tunica albuginea play in penile structure?
The tunica albuginea is a fibrous sheath that envelops each of the three cylindrical masses of erectile tissue in the penis body. This connective tissue layer helps contain and support the erectile tissues, maintaining their structural integrity during both flaccid and erect states.
Q7: How does the penis serve both reproductive and urinary functions?
The penis serves dual roles through its anatomical design: the corpus spongiosum surrounds the urethra, allowing urine passage during urination, while the erectile tissues enable sexual function. During ejaculation, the corpus spongiosum keeps the urethra open for semen passage, integrating both reproductive and excretory functions.