13. Pectinate (dentate) line Flashcards Preview

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Flashcards in 13. Pectinate (dentate) line Deck (20)

pectinate ( dentate) line formation/ aka

formed where endoderm ( hindgut) meets ectoderm
aka: dentate line


pathology above vs below pectinate ( dentate ) line

above: 1, internal hemorrhoids 2. adenocarcinoma
below: 1. external hemorrhoids 2. anal fissures 3. squamous cell carcinoma


above vs below pectinate ( dentate ) line according to arterial supply

above--> superior rectal artery ( branch of IMA)
below --> inferior rectal artery --> inferior mesentery vein --> splenic vein --> portal vein
-Lymphatic drainage : internal iliac nodes


below pectinate ( dentate) line - artery and venous and lymph nodes

- artery : inferior rectal rectal artery ( branch of pudendal artery
- venous : inferior rectal vein ( branch of internal pupendal vein --> internal iliac vein --> common iliac --> IVC -
- lymphatic drainage : superficial inguinal nodes


internal vs external hemorrhoids

internal --> not painful ( receive visceral innervation)
external --> painful ( somatic innervation - inferior rectal branch of pupendal nerve )


anal fissure - definition and location ( why)

tear in the anal mucosa located below the pectinate line and posteriorly ( poorly perfused area)


anal fissure - clinical presentation / associated with

1. pain while pooping
2. blood on paper toitel
associated with : 1. low fiber diet 2. constipation


• What type of hemorrhoids occur above the pectinate line? Below the pectinate line?

Internal; external


• A patient presents with pain on defecation. You find that he has somatically innervated swollen masses on exam. What nerve innervates them?

Innervated by somatic nerves (the pudendal nerve) (these are external hemorrhoids) and thus are painful (internal hemorrhoids are not)


• A patient is diagnosed with cancer occurring above the pectinate line. What kind is it? What if it were below the pectinate line?

Adenocarcinoma (endodermal derivation); squamous cell carcinoma (ectodermal derivation


• Above the pectinate line, lymphatic drainage is to what nodes?

Deep nodes


• Below the pectinate line, lymphatic drainage is to what nodes?

Superficial inguinal nodes


• Above the pectinate line, the blood supply comes from what artery?

The superior rectal artery (branch of the inferior mesenteric artery)


• The superior rectal artery is a branch of what artery that comes off the aorta?

The inferior mesenteric artery


• Innervation below the pectinate line is somatic or visceral?

Somatic innervation (hemorrhoids there are painful)


• Below the pectinate line, the arterial supply is from what artery?

The inferior rectal artery


• The inferior rectal artery is a branch of what artery?

The internal pudendal artery


• A 52-year-old man has rectal bleeding and a painful mass that flares up during defecation. Which nerve is involved?

Inferior rectal branch of the pudendal nerve (this is most likely an external hemorrhoid, which received somatic innervation)


• A patient has a tear in the anal mucosa below the pectinate line. What is this called? Where is it most likely found on the anus?

Anal fissure; Posteriorly (below Pectinate line, Pain on Pooping, blood on Paper; located Posteriorly where it is Poorly Perfused)


• A patient with cirrhosis has internal hemorrhoids. Describe the pathway for venous drainage to the portal system, which is likely impaired.

Superior rectal vein to inferior mesenteric vein to portal system

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