Flashcards in 254. Anatomy of the bladder Deck (16):
What is the normal capacity for urine storage in the bladder?
What ligaments firmly hold the bladder by its neck?
Puboprostatic or pubovesical ligaments
What is the median umbilical ligament?
Remnants of an obliterated urachus which was for draining the bladder to the umbilical cord before birth
What epithelium lines the bladder and why?
Transitional epithelium - can expand upon distension
What tissues are present in the bladder submucosa?
Connective and elastic
What are the 3 smooth muscle layers of the bladder?
Longitudinal, circular and spiral
Men have an internal and external urethral sphincter whereas in women they only have one urethral sphincter.
Name and describe the two muscles that make up the external urethral sphincter.
- striated muscle
- small 'slow twitch' fibres, mitochondria/lipid droplets, rich in myosin ATP-ase
Peri-urethral striated muscle (pelvic floor)
- mixture of fast and slow twitch larger fibres
What are the factors which contribute to urethral closure?
Muscular occlusion by rhabdosphincter
Transmission of abdominal pressure to proximal urethra
Mucosal surface tension
Anatomical configuration at bladder neck
Submucosal vascular plexus
What is the venous drainage of the bladder?
Rich plexus of veins which drain into the internal iliac veins
What is the lymphatic drainage of the bladder?
Vesical, internal iliac, external iliac, and common iliac lymph nodes
Describe the pathway of afferent neurones in the bladder and their role (simple nerve endings)
Simple nerve endings in lamina propria/detrusor
Travel with parasympathetic neurones back to the cord and then to the pontine and micturition centres
Responsible for sensing stretch, bladder filling, and pain
Have 'polymodal receptors' (more than one stimulus) which can be sensitised or desensitised
What is the afferent sympathetic innervation of the bladder?
Hypogastric nerve - responsible for pain, touch, temperature
What is the parasympathetic motor innervation of the bladder? Describe its pathway
Sacral pre-ganglionic parasympathetic nuclei in intermediolateral columns of S2, 3, 4
Run with PELVIC nerves via pelvic plexus to synapse with ganglion cells close to and within bladder wall
Post ganglionic axons provide cholinergic excitatory input to detrusor smooth muscle
What is the sympathetic motor innervation of the bladder? Describe its pathway
Pre-ganglionic sympathetic nerve fibres arise from T10-12 and L1-2
Travel in HYPOGASTRIC nerves and innervate trigone/blood vessels of bladder and smooth muscle of prostate in men
In females there is a sparse innervation of bladder neck and urethra
In both sexes: some post-sympathetic nerves terminate in parasympathetic ganglion and exert 'inhibitory' effect (Gating theory)
Describe the dual innervation of the urethral sphincter
Pre-ganglionic somatic nerve fibres innervate striated muscle
Parasympathetic nerves from S2-4 from ONUF's nucleus which lies in medial aspect of anterior horn of spinal cord
These somatomotor nerves run via the perineal branch of the PUDENDAL nerve