Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ====== ANAL REGION ====== * [[:en:ischioanal_fossa|ISCHIOANAL FOSSA]] {{:anatomy:anus-general.png}} {{:anatomy:anus-sphinchters.png}} * Anal canal * Introduction * Length and direction * 3.8 cm long * anorectal junction to anus * anorectal junction marked by * direction * downward and backward * surrounded by sphincters * inner involuntary muscle * outer voluntary muscle * external opening * anus * 4cm below coccyx * in cleft between buttock * contains ring of apocrine glands * Relations * Anterior * perineal body * males * membranous urethra and bulb of penis * females * lower end of vagina * Posterior * anococcygeal ligament * tip of coccyx * Laterally * ischio-anal fossa * All around * sphincter muscles * interior of anal canal * Upper part ( 15 mm long ) * mucous membrane lining derived from endoderm * 6-10 vertical ridges called * Anal columns [[Morgagni]] * lower end unite to form * anal valves * together form a transverse line opposite internal anal sphincter * pectinate/dentate line * shows epithelial projections called * anal papilla * above each valve is a depression * anal sinus * contains anal glands * peculiar smell in lower animals to attract * Middle part ( 15mm long ) or Anal transition zone or pecten * mucous membrane * no anal columns * bluish appearance * dense venous plexus * lower limit has a whitish appearance * white line of hilton , Anocutaneous line [[Hiltoni]] * interval between * subcutaneous part of external anal sphincter * internal anal sphincter * marks lower limit of pecten * stratified squamous epithelium * thin , pale , devoid of sweat glands * Lower part ( 8mm long ) * lined by true skin * sebaceous glands * sweat glands * hair * epithelium is of pigmented skin * Musculature * anal sphincters * Internal anal sphincter * involuntary * Intersphincteric groove * External anal sphincter * parts * Deep part * Superficial part * Subcutaneous part * control * voluntary * striated muscle * supplied by * inferior rectal nerve * 4th sacral nerve * fiber * uppermost fibers * puborectalis * middle fibers * internal anal sphincter * lower fiber * conjoint longitudinal coat * formed by fusion of * puborectalis with longitudinal muscle coat of rectum * lies between * external and internal anal sphincter * becomes * fibroelastic at level of white line * breaks up in to number of fibroelastic septa * spread out fan wise * corrugator cutis ani * most lateral part forms * peri anal fascia * most medial part forms * intermuscular septum * Anorectal ring * muscular ring * at anorectal junction * formed by fusion of * puborectalis * uppermost fibers of * external anal sphincter * internal anal sphincter * Surgical spaces * [[:en:ischioanal_fossa|ISCHIOANAL FOSSA]] * Perianal space * surround anal canal below white line * contains * lower fibers of external sphincter * external rectal venous plexus * clinical * pus in this space * spreads to anal canal at white line * or surface of perineal skin * Submucous Space * Lies above white line * between mucous membrane and internal sphincter * contains * internal rectal venous plexus * lymphatics * Arterial Supply * Venous drainage * Lymphatic drainage * Control * nerve supply * above pectinate line * below pectinate line * sphincters * Histology * Rectum * Anal canal * Anorectal flexure; perineal flexure * Anorectal junction * Pectinate line * Anal pecten en/anus.txt Last modified: 2024/08/30 12:35by 127.0.0.1