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Anatomy bladder, urethra and internal gonads (Urinary bladder (Internal…
Anatomy bladder, urethra and internal gonads
Urinary bladder
- Ureters
- Superior surface
(urachus)
- Urethra
- 2* inferolateral surfaces (cradled between levator ani) + obturator muscles
- Anterior pelvic organ
- Pyramid shape (on its side)
- Apex:
pubic symphysis; median umbilical ligament (urachus)
- Base:
Posterioinferior
- 2 ureters enter superolateral angles while urethra drains inferiorly
- Superior surface: covered in peritoneum and expands
Internal
- Muscular pouch
- Contains specialized muscle: detrusor muscle:
Involuntary smooth muscle that has an interlacing pattern and controlled by parasympathetic nervous system
Trigone:
- Bounded where the ureters enter superiorly and urethra exits inferiorly
Urethra
- Formed at neck of bladder where 2 inferolateral surfaces and base intersect
(male urethra: surrounded by prostate at this part)
Micturition
- Urine made in kidneys
- Stored in bladder
- Sphincter muscle relax
- Bladder muscle (detrusor) contracts
- Bladder emptied through urethra and urine removed from body
Needs symphathetic nerves: allow bladder to fill and parasymphathetic (lumbar and sacral) nerves to void bladder
- Spinal reflex: facilitated and inhibited by higher brain centre: voluntary
- Parasymp fibres: pelvic splanchnic nerves S2-S4
Stimulates contraction detrusor muscle, inhibits sphincter vesicae
- Symp fibres L1-L2: descending via hypogastric plexus
Little/no action on smooth muscle of bladder: stimulate closure sphincter vesicae
- Somatic - External sphincter
Pudendal nerve S2-S4
Urethral Sphincters
Internal
- Smooth muscle
- Extends into bladder neck
- Controlled by ANS, normally closed by symp stimulation via hypogastric nerve
External
- Histologically different from internal and detrusor muscle
- Skeletal muscle: voluntary control
- Pudendal nerve
- Block symp innervation so detrusor can contract (parasym innervation) and relaxation of internal and external sphincters to release urine
-
-
Urethra
- Originates from neck of bladder, short and supported by pubovesical ligament
- Passes inferiorly through urogenital diaphragm
- Passes through perineal membrane: membranous urethra
- Opens at vestibule between labia minora
Male
Originates from neck of bladder, 4 parts:
- Preprostatic- Bladder to prostate
- Prostatic- Passes through prostate
- Membranous - passes through deep perineal pouch and perineal membrane
- Spongy: surrounded by corpus spongiosum and bulbospongiosus muscle
Supported by prostate surrounding neck of bladder and pubopraostatic lig
Prostate
Prostatic fluid
- 30% total volume of ejaculate (semen)
- Alkaline to counteract acidity vagina
- Secreted though many openings on posterior wall of prostatic urethra
- Ejact ducts pass though prostate in anteroinferior direction through posterior portion of prostate
Seminal Vesicles
- Pair of male accessory glands develop as out pouches from ductus deferens
- Found on posterior surface (base) of bladder, anterior to rectum. Lateral to ducuts deferens
- Joins with ductus deferens to form ejact ducts
- Secretes seminal fluid: majority of ejact: high fructos and alkaline
- Single accessory organ: male repro
- Surrounds neck of bladder and each inferolateral surface sits on levator ani
- Lobes:
Anterior
Lateral lobes (2)
Posterior (of each lobe)
Median (behind urethra and ejact ducts) with median sulcus of the 2 lateral lobes