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Sigmoid Colon
The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''sigma'' + '' -oid''). This part of the colon normally lies within the pelvis, but due to its freedom of movement it is liable to be displaced into the abdominal cavity. Structure The sigmoid colon begins at the superior aperture of the lesser pelvis, where it is continuous with the iliac colon, and passes transversely across the front of the sacrum to the right side of the pelvis. It then curves on itself and turns toward the left to reach the middle line at the level of the third piece of the sacrum, where it bends downward and ends in the rectum. Its function is to expel solid and gaseous waste from the gastrointestinal tract. The curving path it takes toward the anus allows it to store gas in the superior arched portion, enabling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colon (anatomy)
The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being removed by defecation. The colon (progressing from the ascending colon to the transverse, the descending and finally the sigmoid colon) is the longest portion of the large intestine, and the terms "large intestine" and "colon" are often used interchangeably, but most sources define the large intestine as the combination of the cecum, colon, rectum, and anal canal. Some other sources exclude the anal canal. In humans, the large intestine begins in the right iliac region of the pelvis, just at or below the waist, where it is joined to the end of the small intestine at the cecum, via the ileocecal valve. It then continues as the colon ascending the abdomen, across the width of the abdominal cavity as the transverse colon, and then desce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lumbar Splanchnic Nerves
The lumbar splanchnic nerves are splanchnic nerves that arise from the lumbar ganglia (the lumbar part of the sympathetic trunk) and travel to an adjacent plexus near the aorta. They originate from L1 and L2. Together with fibres from the aortic plexus, they form the superior hypogastric plexus. These nerves contain preganglionic sympathetic and general visceral afferent fibers. The site of synapse is found in the inferior mesenteric ganglion and the postsynaptic fibers innervate the smooth muscle and glands A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ... of the pelvic viscera and hindgut. References External links * Nerves {{neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasympathetic Nervous System
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulating the body's unconscious actions. The parasympathetic system is responsible for stimulation of "rest-and-digest" or "feed-and-breed" activities that occur when the body is at rest, especially after eating, including sexual arousal, salivation, lacrimation (tears), urination, digestion, and defecation. Its action is described as being complementary to that of the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response. Nerve fibres of the parasympathetic nervous system arise from the central nervous system. Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve. Three spinal nerves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelvic Splanchnic Nerves
Pelvic splanchnic nerves or nervi erigentes are splanchnic nerves that arise from sacral spinal nerves S2, S3, S4 to provide parasympathetic innervation to the organs of the pelvic cavity. Structure The pelvic splanchnic nerves arise from the anterior rami of the sacral spinal nerves S2, S3, and S4, and enter the sacral plexus. They travel to their side's corresponding inferior hypogastric plexus, located bilaterally on the walls of the rectum. They contain both preganglionic parasympathetic fibers as well as visceral afferent fibers. Visceral afferent fibers go to spinal cord following pathway of pelvic splanchnic nerve fibers. The parasympathetic nervous system is referred to as the ''craniosacral outflow''; the pelvic splanchnic nerves are the ''sacral'' component. They are in the same region as the sacral splanchnic nerves, which arise from the sympathetic trunk and provide sympathetic efferent fibers. Function The pelvic splanchnic nerves contribute to the inner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigmoid Mesocolon
In human anatomy, the mesentery is an organ that attaches the intestines to the posterior abdominal wall, consisting of a double fold of the peritoneum. It helps (among other functions) in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestines. The (the part of the mesentery that attaches the colon to the abdominal wall) was formerly thought to be a fragmented structure, with all named parts—the ascending, transverse, descending, and sigmoid mesocolons, the mesoappendix, and the mesorectum—separately terminating their insertion into the posterior abdominal wall. However, in 2012, new microscopic and electron microscopic examinations showed the mesocolon to be a single structure derived from the duodenojejunal flexure and extending to the distal mesorectal layer. Thus the mesentery is an internal organ. Structure The mesentery of the small intestine arises from the root of the mesentery (or mesenteric root) and is the part connected ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesentery
In human anatomy, the mesentery is an Organ (anatomy), organ that attaches the intestines to the posterior abdominal wall, consisting of a double fold of the peritoneum. It helps (among other functions) in storing Adipose tissue, fat and allowing blood vessels, lymphatics, and nerves to supply the intestines. The (the part of the mesentery that attaches the colon to the abdominal wall) was formerly thought to be a fragmented structure, with all named parts—the ascending, transverse, descending, and sigmoid mesocolons, the mesoappendix, and the mesorectum—separately terminating their insertion into the posterior abdominal wall. However, in 2012, new microscopy, microscopic and electron microscope, electron microscopic histology, examinations showed the mesocolon to be a single structure derived from the duodenojejunal flexure and extending to the distal mesorectal layer. Thus the mesentery is an internal organ. Structure The mesentery of the small intestine arises from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retroperitoneal
The retroperitoneal space (retroperitoneum) is the anatomical space (sometimes a potential space) behind (''retro'') the peritoneum. It has no specific delineating anatomical structures. Organs are retroperitoneal if they have peritoneum on their anterior side only. Structures that are not suspended by mesentery in the abdominal cavity and that lie between the parietal peritoneum and abdominal wall are classified as retroperitoneal. This is different from organs that are not retroperitoneal, which have peritoneum on their posterior side and are suspended by mesentery in the abdominal cavity. The retroperitoneum can be further subdivided into the following: *Perirenal (or perinephric) space *Anterior pararenal (or paranephric) space *Posterior pararenal (or paranephric) space Retroperitoneal structures Structures that lie behind the peritoneum are termed "retroperitoneal". Organs that were once suspended within the abdominal cavity by mesentery but migrated posterior to the pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peritoneum
The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothelium supported by a thin layer of connective tissue. This peritoneal lining of the cavity supports many of the abdomen#Contents, abdominal organs and serves as a conduit for their blood vessels, lymphatic vessels, and nerves. The abdominal cavity (the space bounded by the vertebrae, abdominal muscles, Thoracic diaphragm, diaphragm, and pelvic floor) is different from the intraperitoneal space (located within the abdominal cavity but wrapped in peritoneum). The structures within the intraperitoneal space are called "intraperitoneal" (e.g., the stomach and intestines), the structures in the abdominal cavity that are located behind the intraperitoneal space are called "retroperitoneal" (e.g., the kidneys), and those structures below the intrape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacrum
The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones. The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall, it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pelvic cavity. In a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iliac Colon
The iliac colon is the portion of the descending colon which is situated within the left iliac fossa (between the crest of the left ilium, and the pelvic brim). It is about 12 to 15 cm long. It curves inferior-ward and medial-ward anterior of the iliacus and psoas muscles. It ends by transitioning into the sigmoid colon at the superior aperture of the lesser pelvis. It is covered by peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesotheli ... only on its anterior and lateral surfaces. Additional images File:Gray1165.png, Female pelvis and its contents, seen from above and in front. References Large intestine {{digestive-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lesser Pelvis
The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor. The pelvic cavity primarily contains the reproductive organs, urinary bladder, distal ureters, proximal urethra, terminal sigmoid colon, rectum, and anal canal. In females, the uterus, fallopian tubes, ovaries and upper vagina occupy the area between the other viscera. The rectum is located at the back of the pelvis, in the curve of the sacrum and coccyx; the bladder is in front, behind the pubic symphysis. The pelvic cavity also contains major arteries, veins, muscles, and nerves. These structures coexist in a crowded space, and disorders of one pelvic component may impact upon another; for example, constipation may overload the rectum and compress the urinary bladder, or childbirth might damage the pudendal nerves and later lead to anal weakness. Structure The pelvis has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
