ANAL REGION
- 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
- 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