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In anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
, the mesentery is the double layer of peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
 that suspends the jejunum
Jejunum

The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum....
 and ileum
Ileum

The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum....
 from the posterior wall of the abdomen
Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity....
. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.

mesentery proper (i.e. the original definition) refers to the peritoneum responsible for connecting the jejunum
Jejunum

The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum....
 and ileum
Ileum

The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum....
, parts of the small intestine
Small intestine

In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
, to the back wall of the abdomen.






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In anatomy
Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
, the mesentery is the double layer of peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
 that suspends the jejunum
Jejunum

The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum....
 and ileum
Ileum

The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum....
 from the posterior wall of the abdomen
Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity....
. Its meaning, however, is frequently extended to include double layers of peritoneum connecting various components of the abdominal cavity.

Mesentery (proper)

The mesentery proper (i.e. the original definition) refers to the peritoneum responsible for connecting the jejunum
Jejunum

The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum....
 and ileum
Ileum

The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum....
, parts of the small intestine
Small intestine

In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
, to the back wall of the abdomen. Between the two sheets of peritoneum are blood vessels, lymph vessels, and nerve
Nerve

A nerve is an enclosed, cable-like bundle of Peripheral nervous system axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons....
s. This allows these parts of the small intestine to move relatively freely within the abdominopelvic cavity. The brain, however, cannot map sensation accurately, so sensation is usually referred to the midline, an example of referred pain
Referred pain

Referred pain is a term used to describe the phenomenon of pain perceived at a site adjacent to or at a distance from the site of an injury's origin....
.

Development

The mesentery is derived from what is known in the embryo as the dorsal mesentery
Dorsal mesentery

The portion of mesentery attached to the greater curvature of the stomach is named the dorsal mesentery , and the part which suspends the Colon is termed the mesocolon....
. The dorsal mesentery is larger than the ventral mesentery
Ventral mesentery

Ventral mesentery is the part of the peritoneum closest to the navel....
, which gradually becomes other parts of the peritoneum. Most parts of the ventral mesentery are associated with the liver.

Mesentery (general)


Mesenteries are composed of two layers of peritoneum. The peritoneum that lies on the walls of the abdominopelvic cavity (parietal peritoneum) invaginates at certain parts, with an organ inside this invagination. This invaginated peritoneum (visceral peritoneum) will often surround all but a part of the organ ("bare area"), through which the organ transmits blood vessels and nerves. If this organ is invaginated far enough into the peritoneum, the visceral peritoneum will come in contact with itself, forming the organ's mesentery.

Mesenteries in the body:
  • Mesentery (proper) - surrounds parts of the small intestine
    Small intestine

    In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
     (the jejunum
    Jejunum

    The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum....
     and the ileum
    Ileum

    The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum....
    )
  • Mesocolon - surrounds parts of the colon
    Colon (anatomy)

    The colon is the last portion of the digestive system in most vertebrates; it extracts water and salt from feces before they are defecation from the body....
    • Meso-appendix - peritoneum of the vermiform appendix
      Vermiform appendix

      In human anatomy, the appendix is a blind ended tube connected to the cecum , from which it develops embryologically. The cecum is a pouch-like structure of the Colon ....
    • Transverse mesocolon
      Transverse mesocolon

      The transverse mesocolon is a broad, meso-fold of peritoneum, which connects the transverse colon to the posterior wall of the abdomen.It is continuous with the two posterior layers of the greater omentum, which, after separating to surround the transverse colon, join behind it, and are continued backward to the vertebral column, where they...
       - peritoneum of the transverse colon
      Transverse colon

      The transverse colon the longest and most movable part of the Colon , passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splen...
    • Sigmoid mesocolon
      Sigmoid mesocolon

      The sigmoid mesocolon is the fold of peritoneum which retains the sigmoid colon in connection with the pelvic wall.Its line of attachment forms a V-shaped curve, the apex of the curve being placed about the point of division of the left common iliac artery....
       - peritoneum of the sigmoid colon
      Sigmoid colon

      The sigmoid colon forms a loop which averages about 40 cm. in length, and normally lies within the pelvis, but on account of its freedom of movement it is liable to be displaced into the abdominal cavity....
  • Broad ligament of the uterus
    Broad ligament of the uterus

    The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis....
     - peritoneum of the uterus
    Uterus

    The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation....
    , uterine tubes, and ovaries


Pathology

A lack of blood-supply to the mesentery causes mesenteric ischemia
Mesenteric ischemia

Mesenteric ischemia is a medical condition in which inflammation and injury of the small intestine result from inadequate blood supply.. Causes of the reduced blood flow can include changes in the systemic circulation or local factors such as vasoconstriction or a blood clot....
.

Invertebrate anatomy

In invertebrate
Invertebrate

An invertebrate is an animal lacking a vertebral column. The group includes 98% of all animal species ? all animals except those in the Chordate subphylum vertebrate ....
s, the term mesentery is used for any tissue that divides the body cavity (coelom
Coelom

The coelom is a fluid filled cavity formed within the mesoderm. Coeloms developed in triploblasts but were subsequently lost in several lineages....
) into partitions.

Additional images


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