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Questions and Answers
What type of muscle controls the external urethral sphincter?
What type of muscle controls the external urethral sphincter?
Which nerve controls the external urethral sphincter?
Which nerve controls the external urethral sphincter?
What is the innermost layer of the urethra made of?
What is the innermost layer of the urethra made of?
From where does the urethra receive its parasympathetic innervation?
From where does the urethra receive its parasympathetic innervation?
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What is the primary function of the urethra?
What is the primary function of the urethra?
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Which layer of the urethra is continuous with the bladder?
Which layer of the urethra is continuous with the bladder?
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Which part of the nervous system controls the external urethral sphincter?
Which part of the nervous system controls the external urethral sphincter?
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Which of the following is part of the anatomy of the penis?
Which of the following is part of the anatomy of the penis?
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What type of nerve is the pudendal nerve?
What type of nerve is the pudendal nerve?
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Which layer is responsible for the main force of urine expulsion during urination?
Which layer is responsible for the main force of urine expulsion during urination?
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Study Notes
Male Urethra
- The male urethra is approximately 18-20 cm long, extending from the internal urethral orifice in the urinary bladder to the external opening (meatus) at the end of the penis.
- The urethra is divided into two main parts: posterior urethra and anterior urethra.
Posterior Urethra
- The posterior urethra is relatively short, lying in the pelvis, proximal to corpus spongiosum, and is acted upon by urogenital sphincter mechanisms.
- It is composed of three segments: preprostatic, prostatic, and membranous segments.
Anterior Urethra
- The anterior urethra is relatively long, surrounded by corpus spongiosum, and functions as a conduit.
- It is composed of bulbar (proximal component) and penile parts.
Prostate
- The prostate is a small, walnut-shaped gland that surrounds the urethra.
- It produces a fluid that helps nourish and transport sperm.
- The prostate is divided into four lobes: two lateral lobes, an anterior lobe, and a posterior lobe.
- It is responsible for producing a fluid that makes up about 30% of the volume of semen.
Other Male Reproductive Organs
- Testes: Produce sperm and testosterone.
- Epididymis: A coiled tube located on the back of the testes where sperm mature and are stored.
- Vas Deferens: Tubes that carry sperm from the epididymis to the urethra.
- Seminal Vesicles: Glands that produce a fluid that nourishes and protects sperm.
- Prostatic Urethra: The part of the urethra that passes through the prostate.
- Membranous Urethra: The shortest part of the urethra, passing through the pelvic floor.
- Penile Urethra: The part of the urethra that passes through the penis.
- Glans Penis: The head of the penis.
- Prepuce: A fold of skin that covers the glans penis.
Muscles of the Abdomen and Pelvis
- Muscles of the Abdomen: Important for core stability, internal organ support, breathing, and trunk rotation.
- Muscles of the Pelvis: Essential for proper bladder and bowel control, as well as supporting the organs in the pelvic cavity.
Clinical Anatomy
- Common injuries in the abdominal and pelvic regions include strains and tears.
- The peritoneal fascia is vulnerable to compromise due to trauma.
Anatomy of the Urethra
- The urethra is surrounded by a coat and inner lining of mucous membrane that is continuous with that of the bladder.
- The outer sheath is composed of striated muscle (external urethral sphincter), controlled by the somatic nervous system.
- The inner sheath is composed of smooth muscle (internal sphincter).
- Smooth muscle fibers, perpendicular to the axis of the urethra, are the innermost layer.
- The urethra receives its innervation from the pelvic splanchnic nerves and the pudendal nerve.
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Description
This quiz covers the structure and parts of the male urethra, including the posterior and anterior urethra.
