Pelvis: Bladder, Rectum, and Anal Canal Flashcards
Ureters in the male pelvis
- Descends on lateral wall of pelvis
- Passes inferior to ductus deferens posterior to bladder in males
Ureters in the female pelvis
- Descends on lateral wall of pelvis
- Passes inferior to uterine vessels in females
Ureters in the female pelvis can be damaged
- During hysterectomy
- Passes inferior to uterine vessels in females
Bladder
- Only superior surface is covered in peritoneum
Bladder location
- Lesser (True) pelvis
- Greater pelvis when distended
- Greater pelvis/abdomen in infants and children
Anatomical relationships of pevlis
- Posterior to pubic bone (males and females)
- Retropubic space (space of Retzius)
Bladder relationships in males
- Prostate is inferior
- Seminal vesicle, ductus deferens, and rectum are posterior
Bladder relationships in females
- Uterus and anterior vaginal wall are posterior
Bladder wall
- Mostly detrusor muscle (autonomic innervation)
- Parasympathetics: contraction
Bladder orifices
- 2 Ureteric
- Internal urethral
Bladder contains
- Bladder wall
- Orifices
- Trigone
- Uvula of the bladder (males)
Parts of the bladder
- Apex
- Fundus
- Body
- Neck
Male urethra
- Conveys urine and semen
Parts of the male urethra
- Intramural
- Prostatic
- Membranous
- Spongy
Neck of the male bladder contains
- Internal urethral sphincter
Internal urethral sphincter (IUS) is innervated by
- Autonomics (Parasympathetics cause relaxation)
IUS (neck of male bladder) prevents
- Retrograde flow of semen
Prostatic part of male bladder
- Passes through prostate
- Seminal colliculus
- Prostatic sinuses
Seminal colliculus (prostatic part of male bladder)
- Openings for ejaculatory ducts - Prostatic utricle
Prostatic sinuses (prostatic part of male bladder)
- Openings for prostatic ducts
Membranous part of male urethra
- External urethral sphincter surround it
- Voluntarily controlled (pudendal nerve)
Spongy part of male urethra
- Travels through corpus spongiosum
- Openings for bulbourethral ducts and urethral glands
Femle urethra
- Short, anterior to vagina
- External orifice opens in vestibule of vagina
- External urethral sphincter more elaborate
Rectum location
- Begins at S3
- Follows sacral curve
Rectum does not contain
- Omental appendices
- Teniae coli
3 lateral flexures of rectum
- Correspond with internal transverse rectal folds
Upper 1/3 of rectum
- Covered with peritoneum anterior and lateral surfaces
Middle 1/3 of rectum
- Covered with peritoneum on anterior surface only
Ampulla of the rectum
- Dilated end of rectum
- Accumulates fecal mass prior to defecation
Anorectal flexure
- Important for fecal continence
- Puborectalis
Parts of the rectum
- Ampulla
- Anorectal junction
Anal junction
- Contains anorectal flexure
Anal canal spans from
- Puborectalis sling to anus
Anal columns
- Longitudinal ridges mucosal folds
- Contain branches of superior rectal artery and tributaries of superior rectal vein
Anal valves
- Junction of columns at inferior end
Anal sinuses
- Pouches above valves
- Contain openings for mucous glands
Pectinate line (Dentate line)
- Junction between embryonic hindgut and skin
- Visceral vs. Somatic: histology, innervation, lymph, blood supply
Anal canal contains
- Anal columns
- Anal valves
- Anal sinuses
Internal anal sphincter located
- Between external anal sphincter and anal canal
- Extends further superiorly
Internal anal sphincter muscle
- Involuntary
- Smooth muscle
- Continuous with muscle of rectum
Internal anal sphincter innervation
- Autonomic nervous system
- Parasympathetic (relax)
- Sympathetic (contract)
Internal anal sphincter has constant tone, but relaxes with
- Distension of rectal ampulla
External anal sphincter
- Extends further inferiorly than the internal
External anal sphincter muscle
- Voluntary
- Skeletal muscle
External anal sphincter innervation
- S4 via inferior rectal nerve
- Also nerve to levator ani
Rectum/anal canal arterial supply
- Superior rectal (inferior mesenteric)
- Middle rectal (internal iliac)
- Inferior rectal (internal pudendal)
Rectum/anal canal venous drainage
- Superior rectal vein (IMV, portal system)
- Middle rectal vein (internal iliac v, caval system)
- Inferior rectal vein (internal pudendal v, caval system
Internal venous plexus and External venous plexus
- Sacculated veins form anal cushions
- Helps with closure of anal canal
Hemorrhoids
- Dilation of internal/external venous plexus
Internal hemorrhoids
- Dilation and prolapse of internal rectal venous plexus
- Painless bleeding
- Internal venous plexus can drain superiorly or inferiorly
Internal hemorrhoids are painless bleeding because of
- Autonomic innervation
Internal venous plexus can drain superiorly or inferiorly due to
- Portal-systemic anastomoses
External hemorrhoids
- External rectal plexus, subcutaneous around the anus
- Can be painful, especially if thrombosed
External hemorrhoids are painful because of
- Somatic sensory innervation
Hemorrhoid cause
- Increased intra-abdominal pressure,
- Impaired venous return
Blood flow above pectinate line
- Columnar epithelium
- Superior rectal artery
- Superior rectal vein (IMV > portal system)
Lymph drainage above pectinate line
- Lymph drainage to internal iliac nodes
Innervation above pectinate line
- Visceral innervation from the inferior hypogastric plexus (autonomics)
Skin above pectinate line
- Columnar epithelium
Skin below pectinate line
- Stratified squamous
Bloow flow below pectinate line
- Inferior rectal artery
- Inferior rectal vein (caval system)
Lymph drainage below pectinate line
- Lymph drainage to superficial inguinal nodes
Innervation below pectinate line
- Somatic innervation from inferior rectal nerves
- Sensitive to touch, temperature
