Applied anatomy

Applied Anatomy( Ureters )  

The ureters have normal constrictions at the following points

  • Ureteropelvic junction
  • Where it crosses the iliac vessels, and the pelvic brim
  • Where it passes through the bladder wall.
  • These must be born in mind when interpreting urograms.
  • They are points of relative stasis of urine and potential sites for start of infection.
  • Renal stones commonly lodge there.

When stones lodge in the ureters, the forceful contraction cause a sharp stabbing pain which follows along the course of the ureters. Because the ureters are innervated by T12, L1, (L2), pain of ureteric colic may be referred to the scrotum, or labia majora.

Urography can map out most abnormalities of the ureters and/ kidneys.

  • Obstruction of the ureters cause backflow of urine leading to hydronephrosis (dilation of the renal calyces) with possible subsequent destruction of renal tissue.
  • When the fatty renal capsule is absent, the kidney descends to an abnormally low level, where it is supported mainly by the renal vessels. This is called nephroptosis (renal ptosis) when the kidney goes low, the ureters may be kinked causing some obstruction.
  • Because the renal fascia is attached in the midline, blood from kidney damage or pus from perinephric abscess CANNOT cross to the opposite side but can force its way into the pelvis.
  • Because of its close relationship to the psoas major, inflamation relate to the kidneys/ureters makes thigh extension very painful.

The common surgical approach to the kidney is from the back - retroperitoneal. During this approach the nerves posterior to the kidney must be safeguarded. However, if peritoneal contamination and/or injury to other abdominal organs is suspected, the transabdominal approach is used.

Kidney transplants are common now so the anatomy of the kidney and ureters is a must

Congenital malformations of the kidneys and ureters may be important clinically e.g

Pelvic kidneys and other ectopic kidneys may cause pressure symptoms wherever they are.

Horseshoe kidneys could occur, and be normally functioning. Normal ascent is usually prevented by the inferior mesenteric artery. They must be remembered when no kidneys are found in the normal position etc.

  1. Membranous Urethra prone to injure in the male as a result of falling astride on objects or a kick in the perineum.
  2. Extravasation of urine from urethral injury in the perineum will be to the
    • scrotum
    • penis
    • anterior abdominal wall
    (see attachment of superficial perineal fascia)
  3. Infections of the urethra especially gonnorcoccal lodge in the Bulbourethral glands of Cowper.Therefore post-gonnorcoccal urethral stricture common in bulba-urethra
  4. Pelvic fractures especially pubic ramus often result in injury to membranous urethra and hence urine extravasation (see 4 ii above).
  5. Lymphatics from the perineum drain into the deep inguinal nodes. Tumours and infections in this area present with swollen inguinal lymph nodes
  6. Episiotomy lateral surgical incision of the vulva and vaginal wall to allow for passage of baby during delivery. This also prevents tears of perineal body.
  7. Anal fistulae
  8. Ischiorectal abscess

 

   

Surgical Approaches to Prostate

Total prostatectomy is the surgical removal of the entire prostate. This operation is performed in cases of early malignant growths. Subtotal prostactomy is the surgical removal of less than the entire organ, and is carried out in cases of nonmalignant growths that interfere with normal urination. Any one of four approaches to the prostate may be used. In supra-pubic prostatectomy the anterior abdominal wall and the wall of the urinary bladder are incised. In retropubic prostatectomy, the anterior abdominal wall is incised, and the approach is made through the retropubic space and the fascia covering the anterior aspect of the prostate. In perineal prostatectomy ( not common ), access to the prostate is gained through the tendinous centre of the perineum and the rectouretralis muscle. Transurethral opening and then through the spongy and membranous parts of the urethra.

   

Clinical coorelates of the Pelvic Diaphragm

1. The pubococcygeus muscle may be damaged during parturition, or during episiotomy, or may be paralysed by a neurological disorder. When this happens, the support for pelvic viscera is weakened markedly. These viscera may herniate out e.g.

a) cystocele = herniation of urinary bladder

b) cystourethrocele = herniation of the urinary bladder and urethra

c) rectocele = herniation of the rectum.

d) uterine prolapse = herniation of the uterus.

2. When the pelvic diaphragm is damaged mildly the support of the urethra and ano-rectum is impaired even though the organs may not herniate. This results in strees incontinence of both urine and stool, more for the urine. In this condition, there is dribbling of urine, whenever the intraabdominal pressure is raised e.g. during coughing or sneezing.

   

Clinical coorelates of the scrotum:

1. Hydrocele

•  This is presence of excess fluid in the processus vaginalis after birth.

•  Infants may accumulate fluid in the cavity of their tunuca vaginalis testis. This is called non-communicating hydrocele. This fluid usually absorbs during the first year.

•  If the processus vaginalis remains patent, peritoneal fluid may be forced into it, forming a communicating hydrocele. This is often associated with indirect inguinal hernia.

•  The proximal and distal ends of the stalk of the processus vaginalis may obliterate, leaving an intermediate cystic area called a hydrocele of the cord.

•  There are several other conditions that can cause hydrocele e.g. trauma, filarial worm infestations stds etc.

   

Some Clinical Coorelates on the Testis

a) Varicocele, is vericostity of the pampini - form plexus. Varicocele, is more common on the left side, and often results from defective valves in the testicular vein. They may temporarily disappear when the person lies down and the scrotum is elevated.

•  Rarely, a varicocele may result from blockage of the renal vein owing to a tumor of the left kidney.

b) Hematocele, of the testis, is a collection of blood in the cavity of the tunica vaginalis, often due to trauma.

c) The difference in lymphatic drainage of the testis and the scrotum is important:

•  Cells from a testicular tumor, may spread through lymphatics to lumbar lymph nodes; those from the scrotum to the superficial inguinal nodes.

d) Vasectomy, is a contraceptive procedure in which the vas deferens is ligated and cut, so that sperms can no longer pass to the urethra.

   

Clinical Coorelates

a. Ischio rectal abscess; A collection of pus in the fossa due to infection therein. Infection may reach the ischiorectal fossa;

•  following infection in the anus

•  from extension of a pelvirectal abscess.

•  following a tear in the anal mucosal membrane.

•  from a penetrating wound in anal region etc.

•  Ischio rectal abscesses are best managed by surgical incision and drainage. If this is not done, the absecess may spontaneously open into; the anal canal; the rectum, the skin in the perineum or all these spaces.

•  The two ischiorectal fossae communicate. Therefore, an abscess in one ischiorectal fossa, may spread to the other one.

b. Pudendal block anaestheia. In this procedure, a local anesthetic agent is injected into the tissues surrounding the pudendal nerve in the pudendal nerve in the pudendal canal. The injection is usually make where the pudendal nerve crosses the lateral aspect of the sacrospinous ligament near its attachment to the ischial spine, which is a good landmark. Pudendal blocks are done to relieve pain in the perineum, e.g. during labour and especially when an episiotomy is required.

   

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Chapter 35: The Male Reproductive System and The Perineum