Pectinate line

The Pectinate Line is a line in the anatomy of the human body, specifically located in the anal canal. It is a significant anatomical landmark that separates the upper two-thirds and lower one-third of the canal. This line is also known as the dentate line.

Anatomy

The Pectinate Line is a horizontal line that marks the boundary between the true rectum and the anal canal. Above the line, the mucosa of the anal canal is similar to that of the rectum, being columnar and vascular. Below the line, the mucosa is stratified squamous and non-vascular, similar to the skin of the perianal area.

Clinical Significance

The Pectinate Line has significant clinical implications. It is the dividing line for the dual blood supply, lymphatic drainage, and nerve supply of the anal canal. Above the line, the blood supply is from the superior rectal artery, a branch of the inferior mesenteric artery. Below the line, the blood supply is from the inferior rectal artery, a branch of the internal pudendal artery.

The lymphatic drainage above the line goes to the internal iliac lymph nodes, while below the line it goes to the superficial inguinal lymph nodes. The nerve supply above the line is from the autonomic nervous system, which does not carry pain fibers. Below the line, the nerve supply is from the somatic nervous system, which does carry pain fibers. This difference in nerve supply is why conditions such as hemorrhoids and anal fissures can be painful if they occur below the Pectinate Line.

See Also

• Anal canal
• Rectum
• Inferior mesenteric artery
• Internal pudendal artery
• Hemorrhoids
• Anal fissures

Pectinate_line

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  Diagram showing hemorrhoids
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  Anatomy of the anal canal
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  Rectoanal junction
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  Diagram of the anorectum
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  Anatomy of the rectum and anal canal