anal canal

(noun)

the terminal part of the large intestine, situated between the rectum and anus

Related Terms

Examples of anal canal in the following topics:

  • Perineum

    • Ischioanal fossa – a fat-filled space at the lateral sides of the anal canal.
    • It is bounded laterally by obturator internus muscle, medially by pelvic diaphragm and the anal canal.
    • Pudendal canal – contains internal pudendal artery and the pudendal nerve.

  • Defecation Reflex

    • A sufficient increase in fecal material in the rectum causes stretch receptors from the nervous system, located in the rectal walls, to trigger the contraction of rectal muscles, relaxation of the internal anal sphincter, and an initial contraction of the skeletal muscle of the external sphincter .
    • The relaxation of the internal anal sphincter causes a signal to be sent to the brain indicating an urge to defecate.
    • The perineal wall is lowered, causing the anorectal angle to decrease from 90 degrees to less than 15 degrees (almost straight), and the external anal sphincter relaxes.
    • The rectum now contracts and shortens in peristaltic waves, thus forcing fecal material out of the rectum and out through the anal canal.
    • The internal and external anal sphincters, along with the puborectalis muscle, allow the feces to be passed by pulling the anus up and over the exiting feces in shortening and contracting actions.

  • Digestive System Development

    • The hindgut is the last third of the transverse colon, descending colon, rectum, and upper part of the anal canal.

  • Histology of the Large Intestine

    • The large intestine consists of the cecum, colon, rectum, and anal canal.

  • Overview of the Spinal Cord

    • This central region surrounds the central canal, which is an anatomic extension of the spaces in the brain known as the ventricles and, like the ventricles, contains cerebrospinal fluid.
    • The nerves that compose the cauda equina supply the pelvic organs and lower limbs, including motor innervation for the hips, knees, ankles, feet, internal and external anal sphincters.

  • Supply of Blood and Nerves to Bone

    • Blood is supplied to mature compact bone through the Haversian canal, formed when individual lamellae form concentric rings around larger longitudinal canals (approx. 50 µm in diameter) within the bone tissue.
    • The canals and the surrounding lamellae (8-15) are called a Haversian system or an osteon.
    • A Haversian canal generally contains one or two capillaries and nerve fibers.
    • Volkmann's canals are channels that assist with blood and nerve supply from the periosteum to the Haversian canal.
    • The Haversian canals surround blood vessels and nerve cells throughout the bone.

  • Impacted Cerumen

    • Earwax, or cerumen, is a yellowish waxy substance secreted in the ear canal which can affect hearing if produced excessively.
    • Earwax, also known by the medical term cerumen, is a yellowish waxy substance secreted in the ear canal of humans and other mammals.
    • Excessive earwax may impede the passage of sound in the ear canal, causing conductive hearing loss.
    • Cerumen is produced in the outer third of the cartilaginous portion of the human ear canal.
    • A curette method is more likely to be used by otolaryngologists when the ear canal is partially occluded and the material is not adhering to the skin of the ear canal.

  • Root Canal Therapy

    • This set of procedures is commonly referred to as a "root canal" .
    • This procedure is known as root canal therapy.
    • The alternatives to root canal therapy include no treatment, tooth extraction, or the 3Mix-MP procedure.
    • Recent studies indicate that substances commonly used to clean the root canal space incompletely sterilize the canal.
    • However, a properly restored tooth following root canal therapy yields long-term success rates near 97%.

  • Episiotomy

    • This area forms the floor of the pelvis and contains the external sex organs and the anal opening.
    • It can be further divided into the urogenital triangle in front and the anal triangle in back.
    • Tears can involve the perineal skin or extend to the muscles and the anal sphincter and anus.

  • Orbits

    • To the rear of the orbit, the optic foramen opens into the optical canal through which the optic nerve and ophthalmic artery pass.
    • The lacrimal and ethmoid bones contribute to the medial wall of the orbit and also to the medial wall of the orbital canal.
    • Finally, the sphenoid bone forms the posterior wall of the orbit and also contributes to the formation of the optic canal.