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Anatomy and function of the prostate.
Hey everyone! This is Nicole from Kenhub, and in this tutorial, we will be looking at an accessory organ of the male reproductive system – the prostate gland. In today's tutorial, we're going to have a little bit of a chat about the prostate gland which is the largest accessory organ of the male reproductive system, and in this slide you can see it here highlighted in green. Now the prostate is situated in the pelvic extraperitoneal space which you can also see in this slide as delineated by the peritoneum. So as we can see here, the peritoneum which is this thin line separating the contents of the peritoneum which as we know holds the stomach, the large intestines and so forth and the pelvic extraperitoneal space which as we can see here contains organs such as the bladder and the rectum.
So the role of the prostate gland is to work as a team with the ductus deferentes which is highlighted here, and the seminal glands which is highlighted here and those two work together to produce semen. Both of these contribute a component to semen, so for example, the ductus deferentes carries sperm from the testes whereas the glans produce special secretions which aid in the survival, nourishment and motility of the sperm. And last of all, the prostate gland secretes a slightly alkaline fluid called prostatic fluid which makes up approximately 30% of the volume of the semen.
So on this slide we're going to have a little look at the location of the prostate gland. So in this slide we can see how the prostate gland can be found inferior to the urinary bladder between the internal urethral sphincter muscles and the external urethral sphincter muscles. Anteriorly, the prostate gland is attached by the pubo-prostatic ligament to the pubic symphysis. And if we have a look over here to the posterior of the prostate, we can see that the ductus deferentes and the ducts of the seminal glands converge to form the ejaculatory ducts which enter the prostate posteriorly.
So on this slide, we're looking at a coronal section of the prostate gland over here and also of the bladder over here and of the urethra over here. The prostate gland is a six-sided structure and it's composed of glandular and fibromuscular tissue and is roughly the size of a chestnut or a walnut. If you held it in your hand, it weighs roughly about twenty grams in a healthy male and it's encapsulated internally by a dense fibrous capsule and externally it's encapsulated by the continuation of the pelvic fascia.
The prostate gland surrounds the proximal part of the urethra called the prostatic urethra which you can see here on this screen in green, and the prostatic urethra is received by the prostate at the neck of the urinary bladder which communicates with the base or the superior aspect of the prostate gland. Now, the seminal colliculus which is highlighted in green is the widest part of the prostatic urethra. Now, this is the part where the ejaculatory ducts which contain the sperm from the ductus deferentes and the secretions from the seminal glands enter into the prostate as shown in this image.
The seminal colliculus is also the location of the openings of the prostatic ducts which derive from the prostatic sinuses on both sides of the prostatic urethra. The final component of semen, fluid from the bulbourethral glands which we can see here – is not added until after the urethra has left the prostate becoming the membranous urethra.
So now we're coming to our slide about neurovasculature and there are three major blood vessels that provide arterial blood to the prostate gland. These being the internal pudendal artery highlighted in green, the inferior vesical artery highlighted in green and the middle rectal artery again highlighted in green. Now, don't forget that all these vessels are branches of the internal iliac artery which I'm just pointing out with my arrow here. Now, the venous blood supply from the prostate is drained via the prostatic venous plexus which we can see here in blue in the image and is indicated by the arrow. The plexus drains into the inferior vesical vein and eventually leads out to the internal iliac vein.
The innervation of the prostate comes from the parasympathetic fibers of the pelvic splanchnic nerves via the prostatic plexus which you can see here in green. The prostatic plexus receives fibers from the inferior hypogastric plexus which in turn also receives fibers from the superior hypogastric plexus that provide motor innervation to the smooth muscle stroma of the prostate gland.
So now we're looking at a coronal section of the bladder, the prostate and the urethra. So two of the most common conditions affecting the prostate typically in men over fifty are benign hyperplasia of the prostate and prostate cancer. Now, these two can most often be distinguished clinically as prostate cancer is usually developed in the posterolateral region of the prostate where nodular growths and prostatic adenocarcinomas can be palpated using a digital rectal examination whereas benign hyperplasia is enlargement of the prostate which can typically result in urinary retention and if not treated can result in a bladder or kidney infection.
Now usually these conditions can be distinguished clinically with the use of a digital rectal examination as the prostate presents differently in each situation. So in the case of benign hyperplasia, a digital rectal examination will reveal a prostate that is smooth and firm, while prostate cancer will result in the palpation of a prostate that is hard and lumpy. Both conditions may sometimes require a prostatectomy which is a total removal of the prostate although for both it really depends on the severity and size of the condition.
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