Anus and Anal Canal Flashcards
Lower opening of anal canal
Anus
Anal triangle is bounded behind by
Coccyx
Anus: Nerve supply of the surrounding skin
Inferior rectal (hemorrhoidal) nerve
Anus: lymph drainage
Superficial inguinal LN
Part of the anus wherein the epithelium is thrown into folds
Anal verge (anocutaneous line)
Part of anal canal without skin appendages
Anoderm
The anal canal
Is divided into upper half and lower half by
Dentate/pectinate line
Located inferior to the dentate line
A. Surgical anal canal
B. Anatomic anal canal
B. Anatomic anal canal
Located inferior to the anorectal line
A. Surgical anal canal
B. Anatomic anal canal
A. Surgical anal canal
What part of the anal canal can you see the following:
Anal columns of Morgagni
Anal valves of Morgagni
Anal valves
A. Upper half
B. Lower half
A. Upper half
Anal canal:
- mucous membrane is derived from HINDGUT of ectoderm
- LE: columnar epitheliun
- thrown into folds
A. Upper half
B. Lower half
A. Upper half
B. Lower half
A. Upper half
Anal canal:
- mucous membranes is derived from ECTODERM
- LE: Stratified squamous
- NO anal columns
A. Upper half
B. Lower half
B. Lower half
In what part of the anal canal can you see the following:
- Hilton’s white line
- Pecten
- Pectinate line
A. Upper half
B. Lower half
B. Lower half
Located between the internal and external anal sphincter - more palpable than visible
Hilton’s white line / intersphincteric line
Located between the Hilton’s line and Dentate line
Pecten
Part of the external anal sphincter that is attached to coccyx and perineal body
Superficial part
- subcutaneous and deep part: no bony attachment
Varicosities of SUPERIOR rectal veins
INTERNAL hemorrhoids
Varicosities of INFERIOR rectal veins
EXTERNAL hemorrhoids
Abscess formed in the glands of the anal crypts
Perianal abscess
- intersphincteric
- ischiorectal
- horseshoe
- pelvirectal (supralevator)
Result of spread or inadequate treatment of anal abscesses
Fistula in Ano
- interaphincteric
- transsphincteric
- supralevator
- extrasphincteric
Contraction o the internal anal sphincter is controlled and maintained by SYMPA fibers from
Superior Rectal (Periatrial) & Hypogastric Plexus
Structure that attaches the external anal sphincter to the perineal body
Anococcygeal ligament
Longitudinal ridges on superior half of mucous membrane of anal canal
Anal columns
Small recesses found superior to the valves
Anal sinuses
Anal canal: blood supply
Superior rectal a
Inferior rectal a (2): inferior to PL, surrounding muscle, perianal skin
Middle rectal a - anastomose
Anal canal: venous drainage
Internal rectal venous plexus then to:
Supe rectal v - Portal system
Infe rectal v - caval venous system
Middle rectal v - muscularis externa of ampulla
Superior rectal vein is a branch of
IMV
Anal canal: Lymph drainage
Supe: Pararectal nodes
Infe: superficial inguinal nodea
Anal canal: Innervation
Supe: inferior hypogastric plexus
- sensi ONLY to stretch
Infe: Somatic inferior rectal nerves
- sensi to pain, touch, temp
Somatic inferior rectal nerve is a branch of
Pudendal nerve
