Anatomy of the prostate and testes Flashcards
What are the general outline of the male reproductive system?
1) Testes
2) Epididymis
3) Vas deference
4) Seminal vesicle
5) Prostate gland
6) Bulbourethral
7) Penis and urethra
What is the function and location of the testes?
- It produces sperms (spermatogenesis) and testosterone (the primary male hormone
- It is housed in the scrotum for good temperature regulation
What is the function and structure of the epididymis?
- It stores and matures the sperm before transportation
- It is a coiled tube located on the back of each testes
What is the function and structure of the vas deferens?
- It transports sperm from the epididymis to the urethra
- It is a muscular tube that joins the ejaculatory ducts
What is the function of the Seminal Vesicles?
- It produces seminal fluid that is rich in fructose to nourish the sperm
- It is located behind the bladder, and it is connected to the ejaculatory duct
What is the function and location of the prostate gland?
- It produces a slightly alkaline fluid that enhances the sperms motility and longevity
- It is a fibro-muscular, walnut-sized gland that surrounds the prostatic urethra below the bladder
- It lies between the neck of the bladder above and the urogenital diaphragm below
What is the function of the bulbourethral (Cowper’s) glands?
It secretes a lubricating pre-ejaculate fluid to neutralize the acidity of the urethra
What is the function and structure of the penis and urethra?
- It facilitates the sexual intercourse and ejaculation, and the urethra serves as a passage for urine and semen
- It is made of erectile tissue (corpora cavernosa and corpus spongiosum)
What are the parts of the prostate gland?
- Base
- Apex
- Four surfaces (anterior, posterior, and two lateral surfaces)
What are the relations of the superior surface of the prostate gland?
- The base is located superiorly and it is related to the neck of the bladder, and the urethra enters at the centre of the base
What are the relations of the apex of the prostate gland?
- The apex is directed inferiorly on the upper surface of the urogenital diaphragm, and the urethra leaves at the prostatis apex
What are the relations of the anterior surface of the prostate gland?
- Related to the pubic symphysis
- It is separated from the retropubic fat, prostatic venous plexus and the deep dorsal vein of the penis
What are the relations of the posterior surface of the prostate?
- Rectum (the rectovesical septum separates the posterior surface from the rectum)
- The rectovesical fascia acts as a barrier to prevent cancer or disease spread (to a small degree)
- This surface is palpable by rectal examination (4-cm above the anus)
What are the lobes of the prostate?
- The prostate is divided into different incomplete lobes (as the connective tissue does not divide them all the way through)
- ANATOMICALY:
- The prostate is divided into three lobes by the horizontal/transverse groove, which divides the prostate into a median lobe (above the sulcus) and two lateral lobes (below the sulcus), which are divided by the median sulcus
- The transverse groove is pierced by the ejaculatory ducts
- Surgical
What is the inferolateral relation of the prostate gland?
It is related to the puboprostatic (2 lateral and 2 medial “where the false capsule is attached to the pubic symphysis”) ligament on either side and the levator ani
What are the prostatic coverings?
- It is invested by an inner true and an outer false capsule
- True capsule: Covers the entire organ and is formed by the condensation of the fibrous stroma of the gland
- False capsule/prostatic sheath: It is derived from the visceral layer of the pelvic fascia
- At the bladder neck, the false capsule is connected to the pubic bones by the medial and lateral puboprostatic ligaments
- The space between the true and false capsule is occupied by the prostatic venous plexus
What are the anatomical lobes of the prostate?
- Median lobe
2) Two lateral lobes
What opens in the transverse groove of the prostate?
The ejaculatory ducts
What are the surgical lobes of the prostate?
- It is incompletely divided into 5 lobes:
- Media (middle lobe): The wedge-shaped part of the gland that is situated between the urethra and the ejaculatory ducts, its upper surface is related to the trigone of the bladder, and it is rich in glands
- Anterior: It lies in front of the urethra, and it is devoided of glandular tissue
- Posterior: Found behind the urethra and below the ejaculatory ducts, it also contains glandular tissue
- 2 Lateral lobes: They lie on either side of the urethra. The lateral lobes contain many glands
What separates the two lateral lobes?
A shallow vertical groove called median sulcus, which can be felt on rectal examination (feels like an elastic swelling)
- In case of a malignant tumor the gland would feel hard and nodular, the groove is obliterated, and the rectl wall becomes fixed to the prostatic fascia
In which lobe of the prostate does benign prostatic hyperplasia occur?
- It affects the median lobe (of the anatomical subdivision), which has a Uvula vesicae as a projection (projects upwards into the bladder as a swelling behind the internal urethral rifice)
- The uvula vesicae would enlarge in benign prostatic hyperplasia, and thus it will impede the internal urethral sphincter, which could lead to the retrograde movement of the semen up the bladder
- This enlargement would obstruct the flow of urine and result in the incomplete emptying of the bladder. Symptoms would include (Frequent micturation, straining during micturation, & diminished stream.
What are the zonal classifications of the prostate?
- Transitional zone (median lobe)
- Central zone (posterior and lateral lobes)
- Peripheral zone (lateral lobes), forms the bulk of the prostate
- Anterior fibro-muscular stroma (anterior lobe)
What is the transitional zone/median lobe?
It surrounds the urethra proximal to the ejaculatory ducts, and it is the main site of benign prostatic hyperplasia
What is the central zone (posterior and lateral lobes)?
It surrounds the ejaculatory ducts and projects under the bladder base
- It is the site of 10% of carcinomas
What is the peripheral zone (lateral lobes)?
- It constitutes the bulk of the apical, posterior, and lateral aspects of the prostate
- 70% of the gland lies in the peripheral zone
- This zone does not undergo benign prostatic hyperplasia, rather it is the site of origin of 70% of all prostate carcinomas
What is the Anterior fibromuscular stroma (non-glandular region)?
It is located in the anteromedial portion of the gland
What is the venous drainage of the prostate?
Prostatic plexus - vesical plexus - internal iliac vein
- The communication between the Batson’s plexus of the paravertebral veins and the vertebral venous plexus could be responsible for the spread of cancer metastasis into the vertebral bodies or intracranial invasion
Describe the structure of the male urethra
- It extends from the neck of the bladder (internal urethral orifice) to the external urethral meatus on the glans of the penis
- It is divided into:
- Prostatic (mot dilated part)
- Membranous
- Penile/spongy (most constricted), AKA external urethral meatus
What is the external urethral meatus?
- Located at the tip of the glans penis
- The glans penis the enlarged distal end of the penis
- The glans penis is covered by the foreskin in circumscribed individuals
- It is formed by the expansion of the corpus spongiosum, which surrounds the urethra
Describe the structure of the prostatic urethra
- It is the widest and most distensible part of the urethra (3cm long)
- It has features in the posterior wall:
- Urethral crest:
- Median longitudinal mucosal fold
- Prostatic utricle:
- Minute depression in the centre of the urethral crest, it represents an embryological remnant (homologuc of the female uretus/vagina)
- Seminal colliculus:
- Rounded eminence at the middle of the urethral creston which the ejaculatory ducts opens
- Prostatic sinus:
- Mucosal gutters on each side of the crest, it receives the opening of the ducts of the prostatic gland
Describe the membranous urethra
- The second narrowest part of the urethra after the external urethral orifice
- It is located at the urogenital diaphragm
Describe the structure of the penile/spongy urethra
- The longest portion of the urethra
- The corpus spongiosum is a vascular erectile tissue that surrounds the urethra
- The corpus spongiosum helps in preventing the urethra from being compressed during an erection (ensuring the correct passage of semen and urine)
- It passe through the bulb and the corpus spongiosum of the penis, and hence it is also called the spongy urethra
- It is expanded at the bulb of the penis to form the bulb of the urethra and in the glans to form the navisular fossa
- The ducts of the bulbourethral glands open into the proximal part of the spongy urethra
What is the corpora cavernosa?
It is a paired structure at the dorsal (top side) of the penis
- It has a major role in the rigidity of the penis, and it fills with blood under parasympathetic control during sexual intercourse
What will happen if the penile urethra is ruptured?
- Rupture of the spongy urethra is common after a severe blow to the perineum (as in falling on a steel bar)
- If torn, urine can go to the superficial perineal space (bounded by colle’s fascia which is continuous with the scarpas fascia “superficial fascia of the abdominal wall”, and the dartos fascia “covers the penis and scrotum”) which allows the urint to collect into the scrotum and the anterior abdominal wall (deep to the superficial fascia) but not into the thigh due to Holden’s line (the line which attaches colles’ fascia to the fascia lata of the thigh)
Describe the structure of the female urethra
- About 4 cm that extends from the bladder to the external meatus
- The musculature at the internal urethral orifice is not organized into an internal sphincter
- The female urethra transverses the urogenital diaphragm
- The paraurethral glands (Skene glands) open near the external urethral orifice, it is located between the urethra and the vagina
- The female urethra is distensible and can be easily dilated without injury; the passage of catheters is easier than in males
- Infections of the bladder and the urethra are more common in females because the urethra is (short, distensiblem, opens into the vestibule of the vagina)
Describe the internal urethral sphincter
- It is involuntary
- It is located at the bladder neck, surrounding the internal urethral orifice
- It is present in males only, and in females the bladder neck provides a passive resistance instead of a true internal sphincter
- It is composed of smooth muscle and encircles the pre-prostatic urethra in males
What is the function of the internal urethral sphincter?
- Prevents retrograde ejaculation (semen from entering the bladder)
- Maintains continence by keeping the bladder outlet closed
- Under autonomic (involuntary) control via the sympathetic nervous system (T11-L2)
- IT RELAXES DURING MICTURATION WHEN THE PARASYMPATHETIC NERVOUS SYSTEM (S2- S4) IS ACTIVATED
Where is the external urethral sphincter located?
- Located in the deep perineal pouch, surrounding the membranous urethra in both males and females
- In males, it is just below the prostate at the level of the membranous urethra
- In females, it is more dispersed and surrounds the mid-urethra
- It is composed of skeletal muscles
What is the function of the external urethral sphincter?
- Provides voluntary control over urination (consciously contracted to delay urination)
- Under somatic control via the pudendal nerve (S2-S4)
- Plays a crucial role in continence (if damaged from prostate surgery, for example, it can lead to urinary incontinence
Describe the development of the testes
- During development, the gonad descends from the posterior abdominal wall to the pelvis in females and the scrotum in males
- Gubernaculum connects the lower poles of the gonads (passing through the anterior abdominal wall) to the labium major in females and the scrotum in males
- Processus vaginalis (an outpouching of the peritoneum that forms alongside the descending testes) precedes the descent of the testes and forms a pathway in the inguinal canal, Normally, it closes after birth, leaving behind the tunica vaginalis, a remnant covering the anterior and lateral parts of the testis
What could happen in the testes of some individuals?
- In some people, testes fail to reach the scrotum, and it usually lies at the normal path of its descent, commonly in the inguinal canal
- This would increase the risk of developing malignancies
What is processus vaginalis?
- Tubular process of peritoneum which descends with the descending testis
- Its neck is usually closed at the time of birth, and if it fails to close, it will result in a hernia
What is tunica vaginalis?
- It is the distal part of the processus vaginalis that remains as the tunica vaginalis of the testes
- It is a closed serous sac with a viceral and a parietal layer
- It contains a small amount of serous fluid
What is the shape and situation of the testis?
- An oval glandular organ that is suspended in the scrotum by the spermatic cord
- During the descend of the testis from the posterior abdominal wall, it collects various coverings
- The left testis lies lower than the right
- The epididymis is related to the posterolateral aspect of the testis
What are the coverings of the testis?
- Extension of the spermatic cord coverings:
1) Internal spermatic fascia (derived from the transversalis fascia) before it we have the parietal layer of the tunica vaginalis
2) Cremaster muscle and fascia (derived from the internal oblique muscle)
3) External spermatic fascia (derived from the external oblique muscle)
4) Superficial fascia of the scrotum which contains the Dartos muscle and fascia
5) Scrotal Skin
What is the sinus of the epididymis?
- It is a slit-like recess of the tunica vaginalis between the body of the epididymis and the posterolateral surface of the testis
- It is located laterally, and it helps us in identifying the side of the testis
What are the structures of the male testis?
1) Tunica albuginea
2) Mediastinum of the testis
3) Fibrous septa
4) Seminiferous tubule
5) Straight tubules
6) Rete testis
7) Efferent ductules
8) Epididymis (head, body, & tail)
9) What is ductus (vas) deferens
10) Ejaculatory ducts
What is the tunica albuginea?
It is the tough outer fibrous surface of the testis
What is the mediastinum of the testis?
It is the thickening of the internal aspect of the tunica albuginea
What is fibrous septa?
It is a septa that extends from the mediastinum inwards between the lobules
What is the seminiferous tubule?
- They are the coiled tubules where spermatogenesis occur (site of sperm production)
What is the straight tubule?
- The end of each seminiferous tubule
- short ducts that join the seminiferous tubules to the rete testis
What is the rete testis?
- A network of canals in the mediastinum of the testis (network of interconnecting channels)
What are the efferent ductules?
Small ducts that drains the rete testis into the epididymus
What are the parts of the epididymis and their functions?
- Tightly coiled tube
- Receives efferent ductules from the rete testis
- Stores and matures the sperms
- Head (enlarged upper extremity): Receives sperm from the efferent ductules
- Body: Site of sperm maturation (gains motility and the ability to fertilize)
- Tail (tapering lower extrimity): Stores the sperm until ejaculation
What is the ductus (Vas) deferens?
- Carries the sperm from the epididymis to the ejaculatory duct
- Travels through the inguinal canal, loops around the bladder, and joins the seminal vesicle duct
What is the ejaculatory ducts?
- Formed by the union of the ductus deferens and the seminal vesicle
- It passes through the prostate and empties into the prostatic urethra
What is a hydrocele?
Excess serous fluid
- To detect it, we require a trans-illumination where a red glow would indicate it
What is a hematocele?
- Collection of blood in the tunica vaginalis
- Does not trans-illuminate
What is the dartos fascia?
Anteriorly, it is a continuation of the scarpa’s fascia and posteriorly with colle’s fascia
What is the dartos muscle?
- Smooth muscle fiber in the superficial fascia (dartos fascia) of the scrotum
- It is supplied by autonomic fibers
- It is responsible for the wrinkles of the skin of the scrotum
What is the scrotal septum?
- Divides the scrotum internally (it is located medially)
- It is a continuation of the dartos fascia
- It is demarcated externally by the scrotal raphe (a cutaneous ridge)
What is the arterial supply of the scrotum?
- Posterior scrotal branches of the perineal artery (a branch of the pudendal artery)
- Anterior scrotal branches of the deep external pudendal artery (a branch of the femoral artery)
- Cremasteris artery (a branch of the inferior epigastric artery)
What is the nerve supply of the scrotum?
1) Lumbar plexus:
- Anterolateral surface: (genital branch of the genitofemoral nerve (L1, L2)
- Anterior surface: Anterior scrotal of the ilioinguinal nerve (L1)
2) Sacral plexus:
- Posterior surface: Posterior scrotal branches of the perineal branch of the pudendal nerve
- Inferior surface: Perineal branches of the posterior femoral cutaneous nerve (S2, S3)
What is meant by vasectomy?
- Ligation of the ductus deferens
- Used for male sterilization
- An incision is made at the top of the scrotum
What is the blood supply of the testis?
- ARTERIES:
- Testicular artery
- Artery of the ductus deferens (a branch of the superior vesical artery)
- VENOUS DRAINAGE
- Pampiniform plexus (drains to the testicular vein), very important due to its temperature regulation role
- Right testicular in (drains to the inferior vena cava)
- Left testicular vein (drains to the left renal vein); the left side faces more varicocities due to it draining into the left renal vein
What is the sympathetic nerve supply of the testis?
-Originates from T10 then - Lesser splanchnic - synapses at the celiac ganglion - post ganglionic fibers - testicular artery - testis
What is the parasympathetic innervation of the testis?
The pelvic plexus
Where does the pain originate from in the testis radiates to?
The region of the umbilicus (T10)
What are the heat regulators of the testis?
- A temperature of 1 degree lower than the body is required for sperm production
- The dartos muscle
- The cremasteric muscle
- The pampiform plexus
How does the dartos muscle regulate the temperature of the testis?
It controls the surface area of the scrotum and hence thermal transfer
How does the cremasteris plexus regulate the temperature of the testis?
It pulls up on the testis to acquire more heat close to the center of the body
How does the pampiform plexus regulate the temperature of the testis?
The heat from the testicular artery is lost into these vessels, and thus, blood reaching the testis is at a lower temperature than the blood reaching the rest of the body
What happens in case of spermatic cord torsion?
- It is a surgical emergency as it can lead to the necrosis of the testis
- Obstructs the venous drainage which results in edema and hemorrhage and subsequently arterial obstruction
- It is most common during adolescence
- A high scrotal incision is made to approach the cord and the testis
- The cord is rotated to untwist the torsion
- To prevent the reassurance or occurrence on the other side, both testis are surgically fixed into the scrotal septum
What is meant by varicocele?
- Dilated and tortuous pampiform plexus
- It might result from:
- Defective valves in the testicular vein
- Abdominal causes could include renal vein problems
- It can be palpated, and it feels like a bag of warm worms
Which testis is more prone to developing a varicocele?
The left side is at a right angle, at which the left testicular vein enters the left renal vein, which is not favorable for flow, and thus reversal flow occurs
- The affected veins are ligated to detous the flow of blood into normal veins
What is cryptochidism?
- When the testis fail to descend by birth
- Occurs in 4% of US live births
- If it was unilateral it is less potent, however if it was bilateral or abdominal the person is considered sterile
- The inguinal canal is a potential site for the testis
