Physiology and pathophysiology of the anal sphincters

The muscles of the pelvic floor and perineum are crucial for supporting the pelvic organs, controlling continence, and aiding in sexual function, childbirth, and core stability. They are typically divided into the superficial perineal layer and the deep pelvic floor layer.
Perineal Layer
The perineum is a diamond-shaped area below the pelvic diaphragm, divided into an anterior urogenital triangle that contains the external genitals and a posterior anal triangle housing the anus. The urogenital...

The physiology of the gastrointestinal system begins with ingestion as food enters the mouth.

The gastrointestinal elimination process involves a complex interplay of neural and hormonal mechanisms that coordinate the final waste removal from the body. This intricate operation encompasses the absorption of water and electrolytes, vital for transforming the remaining indigestible food matter into feces. The large intestine is pivotal in water and electrolyte absorption, forming feces from unabsorbed minerals, undigested food, bacteria, bile pigments, and shed epithelial cells. Essential...

Evaluating the rectum and anus plays a crucial role in conducting a thorough physical examination of the gastrointestinal system. Although it may be uncomfortable and often embarrassing for the patient, it holds immense diagnostic value, particularly in detecting gastrointestinal diseases and abnormalities. This guide will explain how to perform this assessment using inspection and palpation methods.
Rectal Inspection
Begin by inspecting the perianal and anal areas for color, texture, rashes,...

The lower urinary system consists of the urinary bladder and urethra, which are essential in storing and expelling urine from the body. Together with the internal and external sphincters, these structures work together to regulate urination effectively.Anatomy of the BladderThe urinary bladder is a muscular, stretchable organ behind the pubic bone and in front of the rectum. In females, the bladder is positioned anterior to the vagina and inferior to the uterus, while in males, it is located...

DefinitionIrritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by recurrent combinations of abdominal pain, bloating, diarrhea, or constipation.Pathophysiology of irritable bowel syndromeIts pathophysiology is multifactorial, involving disturbances in motility, sensory processing, microbial balance, barrier integrity, and gut–brain communication. These mechanisms interact to produce symptoms that vary across IBS subtypes.Altered Motility PatternsDisordered...