ANAT20006 Lecture Notes - Lecture 20: Pelvic Floor, Urethra, Defecation
23 Jul 2018
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Document Summary
Found in thorax, abdo and pelvis, head, neck. Serosa: external surface, minimizes friction, derived from lining of body cavity (continuous with mesentery) attaching viscera to body wall. Motility (peristalisis- squeezing), expansion (stretched without force of contraction so large volumes can be stored like in stomach, bladder, rectum) At critical point of stretch reflexes cause micturition or defecation. Constrictions: at beginning and end, and specific sites (eg. where male urethra pierces pelvic floor) Dilation: often at adjacent viscera to allow collection (like urine) Duct narrows at orifice (opening- wall of a hollow viscus) Calculus (stone) can lodge at orifice- condensations of salt minerals. Anatomical: muscle thickening, controls passage, reflux, at distal ends of ducts or near external orifice. Involuntary: autonomic ns, 1st line of defence, voluntary, skeletal muscle, somatic nervous system, 2nd line of defence. Functional: no localised muscle thickening, other mechanism contributes to closed lumen. Some have subdivisions (outer cortex and inner medulla)
