Male reproductive tract Flashcards
Name external male genitalia (3)
Penis, urethra and scrotum. PUS
Name internal male genitalia (7)
Seminal vesicle, testes, epididymis, vas deferens, ejaculatory duct, bulbourethral gland, and prostate. STEVEBP
What is the function of the testes? (How many sperm are produced, daily?)
Where do the testes descend from?
The testes are the site of sperm production and hormone synthesis. 120 million sperm daily.
Note that the testes descend from the posterior abdominal wall to the scrotum
Why are the testes situated externally?
The testicles are located outside the body because sperm develop best at a temperature several degrees cooler than normal internal body temperature.
What is the testicular blood supply?
The main arterial supply to the testes and epididymis is via the paired testicular arteries, which arise directly from the abdominal aorta (just inferiorly to the renal arteries). They descend down the abdomen, and pass into the scrotum via the inguinal canal, contained within the spermatic cord.
The testes are also supplied by branches of the cremasteric artery (from the inferior epigastric artery) and the artery of the vas deferens (from the inferior vesical artery) (arises from the internal iliac artery). These branches give anastomoses to the main testicular artery.
Descent through the ‘inguinal canal’ requires a detailed knowledge of the anatomy of the anterior abdominal wall and is important in the development of hernias.
What is the ‘epididymis’ and what is its function & relationship with the testes?
The epididymis has a role in the storage of sperm.
The epididymis consists of a single heavily coiled duct.
The main function is to store sperm and transports it from the testes.
What is the epididymis divided into?
It can be divided into three parts; head, body and tail.
Head – The most proximal part of the epididymis. It is formed by the efferent tubules of the testes, which transport sperm from the testes to the epididymis.
Body – Formed by the heavily coiled duct of the epididymis.
Tail – The most distal part of the epididymis. It marks the origin of the vas deferens, which transports sperm to the prostatic portion of the urethra for ejaculation.
What is the prostate gland?
Where is it positioned?
The ‘prostate gland’ is a fibro-glandular structure in the shape of an inverted cone and situated at the base of the bladder. Positioned inferiorly to the neck of the bladder and superiorly to the external urethral sphincter.
What is the function of the prostate gland?
The prostate secretes proteolytic enzymes into the semen, which act to break down clotting factors in the ejaculate. This allows the semen to remain in a fluid state, moving throughout the female reproductive tract for potential fertilisation.
The proteolytic enzymes leave the prostate via the prostatic ducts. These open into the prostatic portion of the urethra, through 10-12 openings at each side of the seminal colliculus (or verumontanum); secreting the enzymes into the semen immediately before ejaculation.
Which structure passes through the gland, from base to apex?
The urethra.
What are the ‘seminal vesicles’ and what is their relation to the prostate?
They secrete fluid that partly composes the semen, they ultimately provide around 70% of the total volume of semen.
Superior and lateral to the prostate.
What are the ‘ejaculatory ducts’ and where do they open?
Describe the joining of the ducts
What are the seminal vesicles?
The vas deferens combine with the duct of the seminal vesicles to form the ejaculatory duct. They pass through the prostate and subsequently open/drains into the prostatic urethra at the seminal colliculus.
The seminal vesicles are a pair of glands that are positioned below the urinary bladder and vans deferens.
In terms of their relation to the prostate - excretory duct of each of the seminal glands’ unit with the vans deferens to form two ejaculatory ducts which pass through the substance of the prostate gland.
What are the two main divisions of the penis?
Body and glans.
Root – the most proximal, fixed part of the penis. It is located in the superficial perineal pouch of the pelvic floor, and is not visible externally. The root contains three erectile tissues (two crura and bulb of the penis), and two muscles (ischiocavernosus and bulbospongiosus).
Body – the free part of the penis, located between the root and glans. It is suspended from the pubic symphysis. It is composed of three cylinders of erectile tissue – two corpora cavernosa, and the corpus spongiosum.
Glans – the most distal part of the of penis. It is conical in shape, and is formed by the distal expansion of the corpus spongiosum. This contains the opening of the urethra, termed the external urethral orifice.
What are the 3 cylindrical structures that form the penis?
It is composed of three cylinders of erectile tissue – two corpora cavernosa, and the corpus spongiosum.
The male urethra runs through the corpus spongiosum – to prevent it becoming occluded during erection the corpus spongiosum fills to a reduced pressure.
Which structure expands, distally, to form the ‘glanspenis’?
Distally, the corpus spongiosum expands to form the glans penis.
The glans penis is the sensitive bulbous structure at the distal end of the human penis - it’s essentially the head of the penis.
