Anal sphincter muscles

Viscosity data (ASTM D-445, IP 71) are used to ensure that, in the case of oils for internal use as laxatives, unduly fluid material, which could increase risk of leakage through the anal sphincter muscle, is not used. The minimum viscosity is usually on the order of 75cSt at 37.8°C (100°F). The temperature of viscosity measurement is a normal one employed for this purpose and happens, in the case of medicinal oils, to be that of the human body. Thus the viscosity of these oils is measured at their working temperature. 

The anal sac constitutes an inportant fermentative scent source in the carnivores. In the red fox, the two anal sacs form reservoirs of about 1 ml capacity situated laterally to the anus between the internal and the external anal sphincter muscles. Each sac opens to the inner cutaneous anal region through a short duct. Inputs to these reservoirs are the secretions of the glands of the sac walls and desquamated cells from the sac epidermis. ... 

Constipation can be due to primary and secondary causes (Table 18-1). Primary or idiopathic constipation is typified by normal-transit constipation, slow-transit constipation, and dyssynergic defecation. In the normal-transit type, colonic motility is unchanged and patients tend to experience hard stools despite normal movements. In the slow-transit type, motility is decreased leading to infrequent harder, drier stools. In dyssynergic defecation (also known as pelvic floor dysfunction), patients have lost the ability to relax the anal sphincter while coordinating muscle contractions of the pelvic floor. Some causes of secondary constipation are listed in Table 18-1. 

Check anal sphincter tone as an indirect assessment of peripheral innervation to the detrusor muscle of the bladder. 

Dyssynergic defecation A lack of coordination between the pelvic floor muscles and the anal sphincter. 

Continual dribble of fecal matter through the anus is prevented by (1) tonic constriction of the internal anal sphincter, a circular mass of smooth muscle that lies immediately inside the anus, and (2) the external anal sphincter, composed of striated voluntary muscle that both surrounds the internal sphincter and also extends distal to it the external sphincter is controlled by the somatic nervous system and therefore is under voluntary control. 

Morphine reduces the activity of the entire gastrointestinal tract in that it reduces the secretion of hydrochloric acid, diminishes the motility of the stomach, and increases the tone of the upper part of the duodenum. These actions may delay passage of the stomach contents into the duodenum. Both pancreatic and biliary secretions are diminished, and this may also hinder digestion, hi the large intestine, the propulsive peristaltic wave in the colon is reduced, the muscle tone including that of the anal sphincter is increased, and the gastrocohc reflex (defecation reflex) is reduced. These actions, in combination, cause constipation, which seems to be a chronic problem among addicts. 

Certain chronic diseases of the CNS (eg, cerebral palsy, multiple sclerosis, stroke) are associated with abnormally high reflex activity in the neuronal pathways that control skeletal muscle the result is painful spasm. Bladder and anal sphincter control are also affected in most cases and may require autonomic drugs for management. In other circumstances, acute injury or inflammation of muscle leads to spasm and pain. Such temporaiy spasm can sometimes be reduced with appropriate drug therapy. 

Approximately 90%-95% of cases of childhood constipation are likely to represent functional constipation. Rectal distention is present in nearly all cases and failure of the external anal sphincter and/or pub-orectalis muscle to relax during defaecation attempts has been found in the majority of these children. Whilst delayed colonic transit time may be part of the problem, pelvic floor dysfunction seems to be the dominating factor (Loening-Baucke 1993). 

The puborectalis muscle is continuous with the external anal sphincter caudally (Fig. 1.7). The macroscopic distinction between both muscles is provided by the anococcygeal body. The puborectalis has no skeletal attachment dorsally, but the deep portion of the sphincter ani externus is indirectly fastened to the coccyx by the anococcygeal body. 

Fig. 1.7a,b. Computer-assisted reconstructions of a female fetus, a Oblique ventrolateral view, b Descending dorsoventral view, v, vagina Im, longitudinal muscular layer pr, puborectalis muscle eas, external anal sphincter is, internal sphincter pbo, pubic bone... 

Fig. 1.15a-c. Perineal body (arrows) and attached muscles, a Axial section (5 mm) of an adult female at a level with the anal cleft. X2.2. b Axial section of the same specimen (a) at a level with the vaginal hiatus, xl.2. c The sagittal plane pointing out the ventral anorectal wall (arrowheads) and the different muscle layers including the longitudinal muscle cells (asterisks). eas, external anal sphincter... 

Fig. 1.16a-c. Scar (arrows) of an old perineal rupture in axial sections (4 mm) of an adult female, a At a level with the perineum. xO.8. b At a -( level with the fusion of external anal sphincter and puborectalis muscle,... 

Einally, external urethral sphincter (voluntary sphincter, or rhabdosphincter) is a striated circumscribing structure emanating from the bladder neck and bladder base detrusor through the mid-urethra in the female and intermediate prostatic urethra in the male. While also surrounding Cowper s glands in the male, these rhabdosphincter subunits contract, most likely, only with ejaculation (Hutch, 1972 Elbadawi, 1980), along with simultaneous anal rhabdosphincter, bulbo-cavernosus muscle, and cremaster muscle contractions. 

Includes all muscle layers of the anal canal internal (smooth) sphincter, longitudinal (smooth) muscle, external (striated) sphincter... 

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