Dissection - Pelvis & Perineum of people with penises Flashcards
What is the significance of the retrovesicle pouch and the green areas on this image?
Rectovesical pouch is clinically important because it represents the most inferior extent of the peritoneal cavity. Blood or other fluid within the peritoneal cavity can collect in this pouch, where it can be drained via a rectal approach, rather than through open abdominal surgery. The green spaces are also clinically important because they are typically avascular areas that can be useful during surgery
The perineal membrane serves as the anchor for the […].
The root of the penis is made up of what three parts?
Each of the erectile tissues is covered by what muscles?
Root of the external genitalia
Two erectile tissues called the corpora cavernosa, and a midline erectile tissue called the corpus spongiosum.
Either the ischiocavernosus or bulbospongiosus.
Just remember that most of the skeletal muscles in the perineum and the pelvic floor, including the external anal sphincter and external urethral sphincter, are innervated by S2-S4 (generally by branches of the pudendal n.)
Note: the testes, unlike the scrotum, receive sensory innervation from the spinal rami of T10-L1 because they developed high up in the abdomen and dragged their innervation down with them on their descent.
Mostly just remember that the internal pudendal artery supplies the perineum
Describe the descent of the testicles.
Recall that during very early development, a fetus has undifferentiated gonads, which develop relatively high in the abdominal cavity. They are attached to the skin near the urogenital membrane by a structure called the gubernaculum. During development, the gonads descend through the abdominal cavity as the gubernaculum shortens. The kidneys rise in the abdomen, and the two structures pass each other, with the kidneys dragging the ureters up, while the gonads drag their blood supply down. In most fetuses with an XY complement, the testicle, pulled by the gubernaculum, pushes its way through the anterior abdominal wall musculature to create the scrotum from the anterior abdominal wall.Once the sperm are produced, they are stored in the epididymis, a convoluted tube on the posterior surface of the testicle. On the anterior surface of the testicle sits an embryological remnant of the peritoneum called the tunica vaginalis, which is typically an empty potential space.
Blood supply to the testicles comes from […]
Blood drains back to the […] via the […].
A single testicular artery
IVC; testicular or pampiniform plexus
Describe the differences in lymphatic drainage of the testes and scrotum.
A critical consequence of the developmental trajectories of the testes and scrotum is how blood and lymph drain from each structure respectively. Because the testes develop internally and then descend through the abdominal wall to create the scrotum, the testes have a separate blood supply, innervation, and lymph drainage from the scrotum. Lymph from the scrotum drains to the superficial inguinal nodes (just like lymph from the skin of the superior groin). Lymph from the testes drains to the para-aortic nodes (because lymph follows veins, and testicular veins ascend into the abdomen). This differential drainage is essential to understand for deducing how cancer cells spread - a tumor or infection of the testicles will initially metastasize to a different location than an infection of the scrotum.
What is Cryptorchidism?
The testes have a long way to travel during development, and as you now know well, anytime something is supposed to happen during development, there are some chances that it won’t happen. The testes can fail to descend all the way into the scrotum, a condition called cryotorchidism. Here are some places the testis could get stuck. If a child’s testicles haven’t descended by their first birthday, surgery is generally planned to find them. The longer the testes stay in the abdomen or inguinal canal, the more likely that person is to have fertility issues as an adult
What is testicular torsion?
The testes are anchored to the scrotum by a very small ligament that is the remnant of the gubernaculum. Usually, the anchoring ligament helps keep the testicle in place inside the scrotum. However, the testicle can twist, causing pain and eventually tissue death if untreated, as the torsion will pinch off the blood supply to the testicle.
What are hydrocele and variocele?
Varicoceles - the potential for the left renal vein to be compressed, leading to a back-up of venous blood in it and its tributary, the left gonadal vein. A very similar sounding condition that isn’t really related at all is called a hydrocele. When the testicles descend from the peritoneal cavity into the scrotum, they carry some of that peritoneal cavity with them. During development, a connection called the preocessus vaginalis remains open between the periotoneal cavity and the scrotum. During typical development, the connection closes, leaving just a small potential space near the testis called the tunica vaginalis. However, if the processus vaginalis doesn’t completely close off, fluid from the peritoneal cavity can drain into the scrotum, increasing its size, sometimes considerably.
The fossa is full of fat, which allows the rectum to expand during defecation without impinging on any important structures
