Bladder Flashcards
what are the 2 muscles of the bladder
- detrusor muscle, trigone
role of detrusor muscle
smooth muscle. via parasympathetic branches to contract during urination to push the urine out of the bladder and into the urethra.
role of trigone
(triangle) posterior wall formed by ureters and urethral opening. Once stretched signals the brain of its need to empty
two muscular sphincters located in the urethra
Internal urethral sphincter:
external urethral sphincter
internal urethral sphincter
Internal urethral sphincter:
Male – consists of circular smooth fibres, which are under autonomic control. It is thought to prevent seminal regurgitation during ejaculation.
Females – thought to be a functional sphincter (i.e. no sphincteric muscle present). It is formed by the anatomy of the bladder neck and proximal urethra.
external urethral sphincter
has the same both sexes.
It is skeletal muscle, and under voluntary control.
in males the external sphincteric mechanism is more complex, as it correlates with fibres of the rectourethralis muscle and the levator ani muscle.
ligaments in the bladder
- base anchored by several ligaments: pubovesicle & puboprostatic
blood supply pathway to bladder
abdominal aorta > common iliac artery > internal iliac > superior and inferior vesical
venous drainage pathway from bladder
vesical venous plexus > internal iliac veins > common iliac > inferior vena cava
autonomic (sympathetic) nervous supply role
Sympathetic – hypogastric nerve (T12 – L2). It causes relaxation of the detrusor muscle, promoting urine retention.
autonomic (parasympathetic) nervous supply role
Parasympathetic – pelvic nerve (S2-S4). Increased signals from this nerve causes contraction of the detrusor muscle, stimulating micturition.
somatic nervous supply role
Somatic – pudendal nerve (S2-4). It innervates the external urethral sphincter, providing voluntary control over micturition.
