   #copyright

Human abdomen

2007 Schools Wikipedia Selection. Related subjects: Health and medicine

   The human rectus abdominis muscle, part of the human abdomen
   The human rectus abdominis muscle, part of the human abdomen

   The human abdomen (from the Latin word meaning "belly") is the part of
   the body between the pelvis and the thorax. Anatomically, the abdomen
   stretches from the thorax at the thoracic diaphragm to the pelvis at
   the pelvic brim. The pelvic brim stretches from the lumbosacral angle
   (the intervertebral disk between L5 and S1) to the pubic symphysis and
   is the edge of the pelvic inlet. The space above this inlet and under
   the thoracic diaphragm is termed the abdominal cavity. The boundary of
   the abdominal cavity is the abdominal wall in the front and the
   peritoneal surface at the rear.

   Functionally, the human abdomen is where most of the alimentary tract
   is placed and so most of the absorption and digestion of food occurs
   here. The alimentary tract in the abdomen consists of the lower
   oesophagus, the stomach, the duodenum, the jejunum, ileum, the cecum
   and the appendix, the ascending, transverse and descending colons, the
   sigmoid colon and the rectum. Other vital organs inside the abdomen
   include the liver, the kidneys, the pancreas and the spleen.

   The abdominal wall is split into the posterior (back), lateral (sides)
   and anterior (front) walls.

Muscles of the abdominal wall

   Henry Gray (1825–1861). Anatomy of the Human Body.
   Henry Gray (1825–1861). Anatomy of the Human Body.
   Muscle Origin and insertion
   The obliquus externus ( external oblique) muscle is the outermost
   muscle covering the side of the abdomen. It is broad, flat, and
   irregularly quadrilateral. It originates on the lower eight ribs, and
   then curves down and forward towards its insertion on the outer
   anterior crest of the ilium and (via the sheath of the rectus abdominis
   muscle) the midline linea alba.
   The obliquus internus ( internal oblique) muscle is triangularly shaped
   and is smaller and thinner than the external oblique muscle that
   overlies it. It originates from Poupart's ligament/ inguinal ligament
   and the inner anterior crest of the ilium. The lower two-thirds of it
   insert, in common with fibers of the external oblique and the
   underlying transversus abdominis, into the linea alba. The upper third
   inserts into the lower six ribs.
   The transversus abdominis muscle is flat and triangular, with its
   fibers running horizontally. It lies between the internal oblique and
   the underlying transversalis fascia. It originates from Poupart's
   ligament, the inner lip of the ilium, the lumbar fascia and the inner
   surface of the cartilages of the six lower ribs. It inserts into the
   linea alba behind the rectus abdominis.
   The rectus abdominis muscles are long and flat. The muscle is crossed
   by three tendinous intersections called the linae transversae. The
   rectus abdominis is enclosed in a thick sheath formed, as described
   above, by fibers from each of the three muscles of the lateral
   abdominal wall. They originate at the pubic bone, run up the abdomen on
   either side of the linea alba, and insert into the cartilages of the
   fifth, sixth, and seventh ribs.
   The pyramidalis muscle is small and triangular. It is located in the
   lower abdomen in front of the rectus abdominis. It originates at the
   pubic bone and is inserted into the linea alba half way up to the
   umbilicus (belly button).

Abdominal organs

   The relations of the viscera and large vessels of the abdomen.
   The relations of the viscera and large vessels of the abdomen.

   The abdomen contains most of the tubelike organs of the digestive
   tract, as well as several solid organs. Hollow abdominal organs include
   the stomach, the small intestine, and the colon with its attached
   appendix. Organs such as the liver, its attached gallbladder, and the
   pancreas function in close association with the digestive tract and
   communicate with it via ducts. The spleen, kidneys, and adrenal glands
   also lie within the abdomen, along with many blood vessels including
   the aorta and inferior vena cava. Anatomists may consider the urinary
   bladder, uterus, fallopian tubes, and ovaries as either abdominal
   organs or as pelvic organs. Finally, the abdomen contains an extensive
   membrane called the peritoneum. A fold of peritoneum may completely
   cover certain organs, whereas it may cover only one side of organs that
   usually lie closer to the abdominal wall. Anatomists call the latter
   type of organs retroperitoneal.

Surface landmarks of the abdomen

   In the mid-line a slight furrow extends from the ensiform cartilage/
   xiphoid process above to the symphysis pubis below, representing the
   linea alba in the abdominal wall. At about its midpoint sits the
   umbilicus or navel. On each side of it the broad recti muscles stand
   out in muscular people. The outline of these muscles is interrupted by
   three or more transverse depressions indicating the lineae transversae.
   There is usually one about the ensiform cartilage, one at the
   umbilicus, and one between. It is the combination of the linea alba and
   the linea transversae which form the abdominal "six-pack" sought after
   by many people. A body fat of around 10% or below with a bodyweight
   that is not underweight is required to see them.

   The upper lateral limit of the abdomen is the subcostal margin formed
   by the cartilages of the false ribs (8, 9, 10) joining one another. The
   lower lateral limit is the anterior crest of the ilium and Poupart's
   ligament, which runs from the anterior superior spine of the ilium to
   the spine of the pubis. These lower limits are marked by visible
   grooves. Just above the pubic spines on either side are the external
   abdominal rings, which are openings in the muscular wall of the abdomen
   through which the spermatic cord emerges in the male, and through which
   an inguinal hernia may rupture.

   One method by which the location of the abdominal contents can be
   appreciated is to draw three horizontal and two vertical lines.

Horizontal lines

   Front of abdomen, showing surface markings for duodenum, pancreas, and
   kidneys.
   Front of abdomen, showing surface markings for duodenum, pancreas, and
   kidneys.
     * The highest of the former is the transpyloric line of C. Addison,
       which is situated half-way between the suprasternal notch and the
       top of the symphysis pubis, and often cuts the pyloric opening of
       the stomach an inch to the right of the mid-line. The hilum of each
       kidney is a little below it, while its left end approximately
       touches the lower limit of the spleen. It corresponds to the first
       lumbar vertebra behind.

     * The second line is the subcostal, drawn from the lowest point of
       the subcostal arch ( tenth rib). It corresponds to the upper part
       of the third lumbar vertebra, and it is an inch or so above the
       umbilicus. It indicates roughly the transverse colon, the lower
       ends of the kidneys, and the upper limit of the transverse (3rd)
       part of the duodenum.

     * The third line is called the intertubercular, and runs across
       between the two rough tubercles, which can be felt on the outer lip
       of the crest of the ilium about two and a half inches (60 mm) from
       the anterior superior spine. This line corresponds to the body of
       the fifth lumbar vertebra, and passes through or just above the
       ileo-caecal valve, where the small intestine joins the large.

Vertical lines

   The two vertical or mid-Poupart lines are drawn from the point midway
   between the anterior superior spine and the pubic symphysis on each
   side, vertically upward to the costal margin.
     * The right one is the most valuable, as the ileo-caecal valve is
       situated where it cuts the intertubercular line. The orifice of the
       vermiform appendix lies an inch lower, at McBurney's point. In its
       upper part, the vertical line meets the transpyloric line at the
       lower margin of the ribs, usually the ninth, and here the
       gallbladder is situated.

     * The left mid-Poupart line corresponds in its upper three-quarters
       to the inner edge of the descending colon.

   The right subcostal margin corresponds to the lower limit of the liver,
   while the right nipple is about half an inch above the upper limit of
   this viscus.

Regions of the abdomen

   Surface lines of the front of the thorax and abdomen.
   Surface lines of the front of the thorax and abdomen.

   These three horizontal and two vertical lines divide the abdomen into
   nine "regions." (Note that "hypo" means "below" and "epi" means
   "above", while "chond" means "cartilage" (in this case, the cartilage
   of the rib) and "gast" means stomach. The reversal of "left" and
   "right" is intentional, because the anatomical designations reflect the
   position on the patient. )
   right hypochondriac/ hypochondrium epigastric/ epigastrium left
   hypochondriac/hypochondrium
   right lumbar/ flank/lateral umbilical left lumbar/flank/lateral
   right inguinal/ iliac hypogastric/ pubic left inguinal/iliac

   Another way of dividing the abdomen is by using quadrants:
   upper right quadrant ( RUQ) upper left quadrant
   lower right quadrant        lower left quadrant

   Retrieved from " http://en.wikipedia.org/wiki/Human_abdomen"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
