Comparison between tract and nerve

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  Comparison between tract and nerve Nerve Nerve contain bundle of axons (nerve fibers) in the peripheral nervous system (PNS) that transmits signals between the central nervous system (CNS) and other parts of the body. It is the most important part of peripheral nervous system Location: Peripheral nervous system. Structure: Made of axons, connective tissue layers (endoneurium: axon is surrounded by it , perineurium: bundle of axons are surrounded by it, epineurium: whole nerve trunk is surrounded by it), and blood vessels. It gets myelination by Schwann cell   Function: Carries sensory signals to the CNS (afferent) from peripheral part of body or motor signals carry from from the CNS (efferent) to target organs like skeletal muscle, cardiac muscle, smooth muscle or glands Example: Sciatic nerve, median nerve, except optic nerve (though optic nerve is technically part of CNS in develop...
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Difference between sigmoid colon and rectum

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Difference between sigmoid colon and rectum

Sigmoid colon
Rectum
It begins at left pelvic brim as a continuation of descending colon and ends in front of the third sacral vertebra
It begins as continuation of sigmoid colon in front of the third sacral vertebra and is continuous with the anal canal
Length: 40 cm
Length: 12 cm
It is suspended from the posterior pelvic wall by a peritoneal fold the sigmoid mesocolon
Upper 1/3 : anterior surface and both lateral surfaces are covered by peritoneum
Middle 1/3 : only anterior surface is covered by peritoneum
Lower 1/3 : devoid of peritoneum
It is supplied by 3-4 sigmoid arteries derived from the inferior mesenteric artery
It is supplied by superior rectal artery , branch of inferior mesenteric artery
Middle rectal artery is a branch of the anterior division of each internal iliac artery
Inferior rectal artery , a branch of internal pudendal artery
It is drain into portal system via inferior mesenteric vein
Rectal veins are important sites of communication between portal and systemic veins
Clinical condition: volvulus : hugely distended colon. it occur due to twisting of sigmoid mesocolon
Clinical condition: primary internal piles
Taenia coli are present
Absent

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