Seminal vesicle

Lecture # 6

Rectum and Bladder

Rectum

- Rectum

· It begins from anterior of 3rd sacral vertebrae and terminates 3 to 4 cm anteroinferior to the tip of the coccyx where it becomes the anal canal.

· The puborectalis muscle forms a U-shaped sling at the junction of rectum and anal canal, producing the 90 degree anorectal angle.

· The anterior dilation of the terminal part of the rectum is known as the rectal ampulla, which is very distensible.

· Inferiorly rectum lies posterior to the prostate in male and the vagina in female.

Peritoneal relations of the

rectum

· Peritoneal relations of the rectum

¯ Superior third : is covered by peritoneum in its anterior and lateral surfaces.

¯ Middle third: has peritoneum only on its anterior surface.

¯ Inferior third: has no peritoneum covering.

¯ In male: peritoneum is reflected from anterior surface of rectum to the posterior wall of the bladder, where it forms the floor of rectovesical pouch (marked as

number 6 in the picture).

¯ In female: peritoneum is reflected from the rectum to the posterior part of the fornix of the vagina, where it forms the floor of the rectouterine pouch (pouch

of douglas, marked as number 6).

¯ In both sexes, lateral reflections of the peritoneum from the rectum form pararectal fossa on each side of rectum. Pararectal fossa allows rectum to distend.

Pararectal Fossa

Pararectal fossa allows rectum to

distend.

Posterior relations of rectum

· Posterior relations of the rectum. Rectum is surrounded by a fascia sheath and is loosely attached to the anterior surface of the sacrum. Posteriorly it rests on the:

- Inferior three sacral vertebrae

- Coccyx

- Anococcygeal ligament

- Median sacral vessels

- Branches of the superior rectal artery

- Inferior ends of the sympathetic trunks

- Sacral plexus

Anterior relations of the rectum

· Anterior relations of the rectum

¯ In male; anteriorly is related to the fundus of the bladder, terminal parts of the ureters, ductus deferens, seminal vesicles and prostate. The two layers of the

rectovesical septum lie in the median plane between bladder and rectum.

¯ In female; anteriorly is related to vagina and it is separated from the posterior part of the fornix of the vagina and cervix by rectouterine pouch. Inferior to

this pouch, the weak rectovaginal septum separates the vagina and rectum.

Shape and flexures of the rectum

· Shape and flexures of the rectum

¯ It has three sharp flexures or curves. Its terminal part bends sharply in a posterior direction, where it joins the anal canal. The bend is the anorectal flexure.

¯ Rectum is S-shaped in cronal section. At each of the concavities, which are formed by the three flextures, there are infoldings of the mucous and submucous

coats and most of the circular muscle layer, called transverse rectal folds. These folds partly close the lumen of the rectum.

Arterial supply of the rectum

· Arterial supply of the rectum

¯ Superior rectal artery which is continuation of inferior mesentric. It divides to left and right branches posterior to superior portion of the rectum.

¯ Two middle rectal which are branches of internal iliac artery.

¯ Inferior rectal arteries, which are branches from internal pudendal arteries.

¯ Small branch posteriorly from median sacral artery.

Venous drainage of the rectum

· Venous drainage of the rectum is by

¯ Superior rectal vein

¯ Middle rectal vein

¯ Inferior rectal vein

· Rectal venous plexus consists of two parts:

¯ An internal rectal venous plexus,

¯ An external rectal venous plexus

. The superior part of the external venous plexus drain into superior rectal vein.

. The inferior part of the external venous plexus drain into internal pudendal vein.

. The middle part drain into the middle rectal vein and then into internal iliac vein.

. The superior rectal vein drains into the portal system whereas inferior and middle rectal veins drain into systemic vein.

Clinical problems related to rectum

• The anastomoses of the arteries is very extensive in the wall of rectum, so that the middle and inferior rectal arteries can supply the entire rectum if the superior

rectal has to be clamped during surgery.

• The rectal veins are an important area of the portacaval anastomoses.

• Many structures related to the anteroinferior part of the rectum may be palpated through its wall e.g, -

- In male; prostate and seminal vesicles

- In female; cervix and vagina

- In both sexes

· The ischial spine and tuberosity

· Enlarged internal iliac lymph nodes

· Pathological thickening of the uterus in female

· Swelling in the iscioanal fossa (abscesses)

· Abnormal contents in the rectovesical pouch in male, or rectouterine pouch in

female

· The inflamed vermiform appendix

• The rectum can also be examined with a proctoscope and biopsies of lesions may be taken through it.

• During insertion of a sigmoid scope the curvature of the rectum at the rectosigmoidal junction have to be kept in mind.

· Pelvic surfaces of sacrum and coccyx

Urinary organs

- Urinary organs Consist of :

· Two kidneys that produce urine.

· Two ureters that convey the urine into the bladder.

· Bladder, a temporarily reservoir for urine.

· Urethra, passes the urine from the bladder to the exterior.

The ureter

· Ureter;

¯ It passes over pelvic brim In the pelvis

¯ It pass anterior to the origins of the external and internal iliac arteries.

¯ It run in the lateral wall of the pelvis, external to parietal peritoneum superior to the ischial spines.

¯ In male the only structure that passes between the ureter and the peritoneum is the ductus deferens. The ureter lies lateral to ductus deferens and enters to

the bladder.

¯ In female as it runs in the lateral wall of pelvis it forms the posterior boundary of the ovarian fossa. At the level of ischial spine it is crossed superiorly by the

uterine artery and passes close to the lateral portion of the fornix of the vagina especially on the left side, and enters the bladder.

¯ Arterial supply of the pelvic part of the ureter is by

. Internal iliac

. External iliac

. Branches of uterine arteries in female

. Inferior vesical arteries in male

¯ Veins accompany the arteries and have the corresponding names.

Ureter obstruction

• Obstruction of the ureter may result from calculi or kidney stones. Their presence can be confirmed by abdominal radiographs. They can be removed in three

ways:

- Open surgery

- Endourology

- Lithotripsy

Urinary bladder

· Bladder

¯ It is a hollow muscular vesicle for storage of urine. It is characterized by its distensibility. Its size, shape, position and relation vary with the amount of urine it

contains and with age.

¯ In female the peritoneum is reflected from superior surface of bladder near its posterior border and the anterior wall of uterus where it forms the

Vesicouterine pouch (#4 in the female slide ). This pouch is empty except when the uterus is retroverted (inclined posteriorly).

¯ In male the peritoneum is reflected from the bladder over superior surfaces of the ductus deferens and seminal vesicles and forms the rectovesical pouch (#6).

¯ The bladder is relatively free in extraperitoneal fat, except its neck, which is held firmly by the pubovesical ligaments.

Surfaces of empty bladder

· Empty bladder (in cadaver) has the form of a triangular pyramid whereas, in living (urine in the bladder) more or less is rounded. Empty bladder has four

surfaces:

¯ A Superior

¯ Two inferolateral surfaces (run also anteriorly), which are in contact with the fascia of the levator ani

¯ A posteroinferior surface, which is the fundus (base) of the bladder.

. In male, the fundus of the bladder is related to rectum.

. In female, the fundus of the bladder is related to vagina.

¯ The anterior end known as the apex, points anteriorly, superior to pubic symphysis. Median umbilical ligament (remnant of urachus) passes from the apex of

the bladder to the umbilicus.

¯ The inferior end of the bladder ,where the fundus and inferolateral surfaces converge, is called the neck of the bladder.

¯ In male the neck of the bladder rests on the base of the prostate

The bladder bed

· The entire organ is enveloped by loose connective tissue, called vesical fascia, in which is located vesical venous plexus. The bed is formed on each side by

- Pubic bones

- Obturator internus

- Levator ani muscles

- Rctum( Posteriorly)

Structure of the bladder

· Structure of the bladder; it is composed of three layers:

¯ Mucous membrane;

. The epithelium of the mucous membrane is formed from

transitional epithelium.

. Mucous membrane is folded (rugae) and is loosely attached to

the muscular layer, except in the trigone that the

mucous

membrane is smooth and is firmly attached to the muscle layer.

¯ Muscular layer (detrusor). The muscular layer is arranged in:

. Inner and outer longitudinal

. Middle circular. Toward the the neck these muscles form the

involuntary internal sphincter.

¯ The outer connective tissue.

· The uretric orifices enter the bladder in inferomedial direction

· The uretric orifices and the internal urethral orifice are located at the angles of the trigone .

Arterial supply of the bladder

· Arterial supply of the bladder

¯Anterosuperior part of the bladder in male and female is supplied by the superior vesical arteries which are branches of the internal iliac artery.

¯ Posteroinferior part of the bladder

. In male is supplied by inferior vesical

. In female is supplied by vaginal artery.

¯ Branches from obturator arteries

¯ Branches from inferior gluteal arteries.

Venous drainage of the bladder

· Venous drainage of the bladder

¯ In male; the vesical venous plexus, which is combined with the prostatic plexus drains the blood from the

. Base of the bladder

. Prostate

. Seminal vesicles

. Ductus deferentes

. Inferior end of the ureters

¯ In female; the vesical venous plexus drains the blood from

. Neck of the bladder

. Pelvic part of the urethra

. Dorsal vein of the clitoris

. Communicates with the vaginal plexus

¯ Veins from bladder drain into the internal iliac vein. sometimes may drain via the sacral vein into the vertebral venous plexsuses.

Clinical problems related to bladder

• Suprapubic cystostomy

• Extravasation of urine into peritoneal cavity

• Extravasation of the urine extraperitoneally

• Bladder can be examined by ultrasound, various imaging technique and radiographically.

• Cancers of the bladder develop in the epithelium.

Male urethra

· Male urethra

¯ In male urethra is divided into three parts

. Prostatic urethra; it begins from the internal urethra orifice in the apex of the trigone and it ends by piercing the superior fascia

of the urogenital diaphragm.It is the widest and most dilatable part of the urethra.

– Urethral crest is a median longitudinal ridge in the posterior wall

of the prostatic urethra

– Prostatic sinus is the groove on each side of the urethral crest .

– Seminal colliculus is a round eminence in the middle part of the

urethral crest which has a slitlike orifice.

– The seminal colliculus orific leads into a small vestigial sac called

prostatic utricle.

– The ejaculatory ducts open on each side of the orifice of the

prostatic utricle.

. Membranous urethra

. Spongy urethra

¯ Spongy and membranous urethra have been explained in the perineum section.

Female urethra

· Female urethra

¯ It begins from internal urethral orifice and ends at the external urethral orifice in the vestibule of the vagina.

¯ Its superior part corresponds to the prostatic urethra and its inferior half is homologous with the membranous urethra in male.

¯ Its inferior end is surrounded by the sphincter urethra muscle and some its fibers enclose both the urethra and the vagina.

¯ Paraurethral glands have common duct which opens on each side near the external urethral orifice.

¯ The inferior half of the urethra is in the perineum.

¯ Blood supply is by the internal pudendal and vaginal arteries.

¯ The vein follow the arteries and have similar names

¯ Most of the nerves to the urethra arise from the pudendal nerve