Anatomy

Anatomy of abdomen

The abdomen is also known as belly. The abdomen is a body space situated between the thorax and the pelvis. It contains various organs and system in it. It is important to know about the anatomy of abdomen to know more about the abdomen. Let’s learn more about the anatomy of the abdomen.

The abdomen is the part of the trunk which lies just below the diaphragm. It is a cylindrical chamber extending from the inferior margin of the thorax to the superior margin of the pelvis and lower limb.

The abdomen is margined superiorly by the inferior thoracic aperture and inferiorly by a pelvic inlet which forms two-cavity where the upper part is known as abdomen proper and Lower part is known as the pelvic cavity.

Viscera of abdomen

Abdominal viscera are suspended in the peritoneal cavity by the mesenteries. It is positioned between the cavity and the musculoskeletal wall. Abdominal anatomy includes a major element of the gastrointestinal, system, the caudal end of the oesophagus, stomach, large and small intestine, liver, pancreas and the gallbladder. It also contains the spleen.

The component of the urinary system, kidney and the ureter. It also contains the suprarenal glands and the major neurovascular structure are present in the abdominal viscera. The anatomy of abdomen also tells about the viscera of the abdomen.

Functions of the abdomen

  1. It acts as a house to protect the viscera like the gastrointestinal tract, oesophagus, liver, intestine (large and small), gall bladder, stomach.
  2. It also helps in the breathing process and changing the intraabdominal pressure by contraction of the abdominal wall.

Boundaries of abdomen

Anatomy of abdomen tells us about its boundaries as well. Roof, floor, anterior wall and posterior wall forms the boundary of the abdomen.

Roof: – undersurface of the diaphragm from the roof of the abdomen which moves up and down during breathing and changes the abdominal pressure.

Floor: – pelvic diaphragm from the floor of the pelvic cavity in the posterior part and urogenital diaphragm forms floor of the pelvic cavity in the anterior part.

Anterior wall: – It is formed by the three muscles which are flat and by their aponeuroses. They are rectus abdomens and pyramidialis muscles within the rectus sheath. The anterior wall is elastic & firm which provides protection to abdominal viscera.

Posterior wall: – various retroperitoneal organs, main vessels and nerves is present in the posterior wall. It provides support & nutrition to the various organs by the attachment of various peritoneal folds.

What do we mean by abdominal cavity?

Let’s see the anatomy of the abdomen to know about the abdominal cavity. The larger upper  part is known as the abdominal cavity which is subdivided by the plane of the

Pelvic inlet. It is also called as the abdominal cavity proper. The abdominal cavity proper is mainly used as a clinical term.

The abdominal cavity is the largest cavity of the body. The boundaries of the abdominal cavity are defined below.

  • Superiorly: Diaphragm, which separates it from the thoracic cavity
  • Anteriorly: Anterior abdominal wall, abdominal muscles
  • Posteriorly: Posterior abdominal wall, formed by lumbar.
  • Inferiorly: Continues with the pelvic cavity at the pelvic inlet.
  • Laterally: muscles and  Lower rib  of the Anterior Abdominal wall

What is the content of the abdominal cavity?

The anatomy of the abdomen also deals with the contents present on the abdominal cavity. The content of the abdominal cavity is the organs and glands of the digestive and urinary systems which occupy most of the part of the abdominal cavity.

The anatomy of the stomach includes the anatomy of stomach, anatomy of liver, anatomy of small intestine, anatomy of the large intestine, the anatomy of prostate, the anatomy of vagina, anatomy of the seminal vesicles, the anatomy of the uterus, the anatomy of ureter and more. These organs and glands of abdominal anatomy are present below:

  • Stomach, small intestine, and most of the large intestine.
  • Liver, gallbladder, and pancreas.
  • Two kidneys and upper part of the ureters.
  • Adrenal glands which are also known as suprarenal glands
  • 5Other structures include blood vessels, lymph vessels, nerves, spleen, and lymph nodes.

Stomach

One of the major viscera of the abdominal cavity is the stomach. Here you can learn the anatomy of stomach with its function.

The stomach is one of the largest parts of the digestive tube. Its shape is just like an alphabet“J” and is located in the abdominal cavity just below the Diaphragm little bit left of the midline. The volume capacity stomach in the adult person is about 1500 ml.

Functions of stomach

The major functions and the activities carried out by the  stomach are as follows:

  1. Churning and breaking of food and mixing it with the Gastric juice secreted by specialized glands in its mucosa.
  2. Storing the food temporarily.
  3. Secreting intrinsic factor needed for absorption of Vitamin B12.

Small intestine

The small intestine is a convoluted tube connecting the stomach with the large intestine. It is about 6 m in length and extends from the pyloric sphincter to the ileocecal junction. The small intestine is situated at the central part and lower parts of the abdominal proper cavity which is surrounded by the large intestine.

The  three parts of the small intestine are

  1.  Duodenum
  2.  Jejunum, and
  3. Ileum.

The duodenum is present side by side and is short curved (c-shaped) portion and is about 25 cm long. It is the wider part of the small intestine. The ducts from gallbladder and liver and pancreas enter  into the duodenum of the small intestine

The jejunum is the remaining upper two fifth part of the small intestine and the lower three-fifth is termed as the ileum.

The main functions of the small intestine are digestion of food and absorption of nutrients. It’s all about the anatomy of intestine with it’s function.

Large intestine

Large intestine is one of the largest parts of the abdominal cavity. anatomy of large intestine deals with many organ which are listed below with their details.

The large intestine starts at the end of the ileum as caecum and ends at the anus. Its length is about 1.5 m long and forms an arch coiled around the small intestine. It can be described as it is divided into the following seven parts:

  1. Caecum and appendix.
  2. Ascending colon.
  3. Transverse colon.
  4. Descending colon.
  5. Sigmoid colon.
  6. Rectum.
  7. Anal canal

Functions of large intestine

The main functions of the large intestine are as follows:

  • It helps in the Absorption of water and salts.
  • It helps in the Formation and excretion of faeces.

Liver

The liver is one of the largest gland present in the abdominal cavity of the body.

Where is liver located?

It is situated in the upper right part of the abdominal cavity. It has two major lobes i.e right and left. The right lobe is much larger than the left lobe. Dealing with its location, function includes all detail about the anatomy of liver.

Functions of the  liver

Some important functions of the liver are as follows:

  • Helps in the Metabolism of carbohydrate, fat, and protein.
  • Helps in the detoxification of drugs and poisons.
  • It also helps in the Storage of glycogen and fat-soluble vitamins (ADEK).
  • Secretion of bile.

Gallbladder

The anatomy of liver includes the anatomy of gallbladder too. The gallbladder is present in the pear-shape. 

It is situated on the inferior surface to the right lobe of the liver. It receives bile secreted by the liver, which it stores and concentrates. When fatty food enters the duodenum, the bile is poured into the intestine through the bile duct by the contraction of the walls of the bladder.

Clinical note related to  the   gallbladder

  • Jaundice is a clinical condition which is characterized by yellowing of the skin and sclera of the eyes. This condition occurs when bile enters the blood in liver diseases such as hepatitis or cirrhosis of the liver where the liver cells break down and release bile into the blood.

Pancreas

The pancreas is an elongated lobulated and soft, pale gland. it is a finely lobulated gland. It is grey in colour. It is about 12–15 cm long and situated transversely across the posterior abdominal wall. It has got a  broad head, neck, body, and a narrow tail. 

let’s start anatomy of pancreas wit its head. Head of the gland is present within the duodenum curve, the body is present behind the stomach and tail is present in front of the left kidney. The tail goes as far as to the spleen.

Functions of pancreas

  • It is an exo-endocrine gland. The function of the exocrine part of the pancreas is to produce pancreatic juice containing
  • enzymes which help in digestion of carbohydrates, proteins, and fats.
  • The function of the endocrine pancreas is to secrete hormones, insulin and glucagon, which control the blood glucose level.

Clinical note for the pancreas

  • The Deficiency of insulin released by pancreas results in diabetes mellitus.

Spleen

The spleen is a large wedge-shaped mass of vascular and lymphoid tissue. It is purplish-red in colour and lies high up at the back of the abdominal cavity on the left side behind the stomach.

Functions of spleen

The main functions of the spleen are as follows:

  1. Destruction of red blood cells.
  2. Production of fresh lymphocytes for the bloodstream.

This is all about the anatomy of spleen with it’s functions.

Kidneys

The anatomy of kidney begins with its shape and its location. The kidneys are in bean-shaped.

where are the kidneys located? Also do read the detail about the anatomy of kidney, the anatomy of ureter and it’s location.

It is present in pair and it is an organ situated on the posterior abdominal wall, one on each side of the vertebral column, behind the peritoneum. The right kidney is present usually at a slightly lower level than the left kidney.

Functions of kidneys

  • Helps  to secrete and excrete urine.

Ureters

The ureter is part of the pelvic cavity there are two tubes through which connect the kidneys to the urinary bladder. Both ureter is about 25 cm in length and  having a diameter of about 3 mm.

Functions of ureters

  • Ureters helps in transportation of urine from the kidneys to the urinary

Adrenal glands or Suprarenal glands

It is also one of the important glands of the abdominal cavity. Two suprarenal glands they are right and left adrenal glands. Both glands cover the upper pole of the corresponding kidney.

The right gland is triangular in shape  whereas the left gland is semilunar(half moon like) in shape. Each gland consists of two parts:

They are cortex and medulla.

The function of the cortex is to secrete a number of steroid hormones, which are responsible for:

  • Maintenance of electrolyte and water balance,
  • Maintenance of blood sugar concentration and of the liver and muscle glycogen,
  • Control of inflammatory reactions.

The function of the medulla is to secrete adrenaline and noradrenaline in the blood, which serve as neurotransmitters. The anatomy of the adrenal gland is discussed detail in the next post. you can read it in the post of the anatomy of the kidney.

Urinary Bladder

The urinary bladder is the part of the pelvic cavity. It acts as a reservoir of urine. Its size, shape, and position varies with the amount of urine present there.

When it is  empty it lies in the pelvic cavity, but when it get distended with the urine it expands upward and forward into toward abdominal cavity. The bladder can hold normally up to 500 ml to 600 ml of urine, though this causes pain and also may lead to severe anamolies in future The desire of  the bladder is normally felt when it contains around 250–300 ml of urine.

The two ureters enter into it through its posterior wall.

The urethra leaves the bladder at its neck. the bladder has got neck which is the lowest and most fixed part of the urinary bladder. A thickening of smooth muscle called internal urethral sphincter surrounds the opening of the urethra. It’s all about the anatomy of urinary bladder and the functions of the urinary bladder are discussed below.

Function of urinary bladder

  • The urinary bladder stores urine and passes  it into the urethra.

Urethra

The urethra is a narrow canal. It extends from the inner urethral orifice in the urinary bladder to the outter urethral orifice.

In a male, the urethra length is about 18–20 cm long and in a female, length of urethra is about 4 cm long.

Function of Urethra

In a male, the urethra serves as a common passage for both semen and urine whereas, in a female, the urethra discharges urine from the body.

Prostate Gland

The prostate is a fibrous and Muscular gland commonly know as fibro-musculoglandular organ, which helps to surround the commencement of the urethra in the male.

It is situated in the pelvic cavity behind the pubic symphysis and in front of the rectum. The size of the prostate gland is about chestnut and which is traversed by the urethra and ejaculatory ducts.

Function of prostate gland

The function of the prostate is to secrete a thin, milky fluid, which forms about 30% of the semen and gives it a milky appearance. The prostatic secretion is alkali in nature and provides nourishment to the sperms.

Seminal vesicles

The seminal vesicles are two small fibromuscular pouches lying between the base of the bladder and the rectum.

Function of seminal vesicles

The seminal vesicles secrete an alkali containing fluid which also contains nutrients for the sperms and forms about 60% of the seminal fluid.

Ejaculatory Ducts

In title anatomy of abdomen, you must also read the detail about the anatomy of ejaculatory ducts. The ejaculatory ducts are two narrow tubes about 1 cm in length.

The duct of seminal vesicle and ductus deferens unite to form the ejaculatory duct. They traverse the prostate gland to open into the urethra within the gland (prostatic part of urethra).

Functions of Ejaculatory ducts

The ejaculatory ducts pass the secretions of testes and seminal vesicles into the prostatic urethra.

Uterus

The uterus is a hollow, having thick-wall present and the muscular organ which is situated in the pelvic cavity in between the urinary bladder and the rectum.

The anatomy of uterus mainly deals with its shape because shapes really matter for any disease conditions and other issues. Its shape looks like a pear and it is flattened anteroposteriorly.

In the majority of women, uterus leans forward (anteflexion) and bends forward (anteversion) almost at a right angle to the vagina. In the erect posture, the uterus lies in an almost horizontal position.

The uterus is divided from above downward into following three parts:

  1. fundus,
  2. body, and
  3. cervix.

 The cervix moves  into the vagina through its the anterior wall and reaches into it at the external OS.

Above on either side, it communicates,, with the uterine tubes, which open into it. Below it communicates with the vagina.

Functions of uterus

The functions of the uterus after puberty are:

  • it is  Responsible for the menstrual cycle (MC).
  • It Provides implantation to zygote in its wall.
  • It Allows the growth and development of the embryo and fetus.

Vagina

The vagina is a fibrous and muscular tube known as fibromuscular which extends obliquely downward and forward from the uterus to the vestibule of the vagina the elliptical space between the labia minor and labia major.

The vagina is located in between the urinary bladder form front side, and the rectum and anal canal behind. The vagina has no secretory glands though is kept moist by the various cervical secretions.

Functions of vagina

The functions of the vagina are as follows:

  • It acts as a receptacle for penis during copulation.
  • It gives an elastic passage to the during delivery for the birth of the child.

Uterine tubes

There are two uterine tubes. Both  tubed is about 10 cm in length which extends from the side of the uterus which means between the fundus and body to the ovary where it opens into the peritoneal cavity.

It is divided into the following parts from distal to the proximal end:

  1.  Infundibulum,
  2.  Ampulla,
  3. Isthmus, and
  4. Intramural.

Functions of uterine tubes

The functions of uterine tubes are as follows:

  • It helps to Transport the ovum from the ovary to its lumen and provides a proper suitable site for fertilization.
  • It helps in the transportation of the fertilized ovum to the uterine cavity for implantation.

Ovaries

The ovaries are female gonads. Each ovary is about the size and shape of an almond and is situated in a shallow fossa on the lateral wall of the pelvic cavity behind and below the distal end of the uterine tube.

Functions of ovaries

The ovaries start its function at puberty and continue to discharge the ova every month from about the age of 13 years old to the age of 45 years. we have completing discussing all the detail of the anatomy of abdomen. now you need to know about the regions of the abdomen.

Regions of the abdomen

The anatomy of the abdomen also tells about the regions of the abdomen. Region of the abdomen is also known as the quadrant of the abdomen.

The abdominal cavity is conventionally divided by the clinicians into nine regions by two horizontal and two vertical lines. The vertical lines pass through the mid inguinal point and the horizontal passes by Upper horizontal line correspond to the transpyloric plane. A lower horizontal line between the tubercle of Iliac crest.

The nine regions of abdomen are:

  • Epigastric:  Liver, stomach, pancreas, duodenum lies in this region
  • Left Hypochondriac Region: Spleen, colon, liver, left kidney, small intestine lies in this region
  • Right Hypochondriac Region: Gallbladder, liver, right kidney lies in this region.
  • Umbilical Region: Naval, duodenum, colon, kidneys, major abdominal vessels lies in this region
  • Left Lumbar Region: Descending colon, left kidney, small intestine lies in this region.
  • Right Lumbar Region: Cecum, ascending colon, liver, right kidney, small intestine lies in this region.
  • Hypogastric Region: Urinary bladder, small intestine, sigmoid colon, female reproductive organs lies in this region.
  • Left Iliac/Inguinal Region: Small intestine, descending colon, sigmoid colonies in this region.
  • Right Iliac/Inguinal Region: Appendix, cecum, small intestine lies in this region.

Some of the disorder Related to the abdomen and the pelvic are:

  • Hernia: protrusion of an organ through the wall, which retains it. The common abdominal hernias are inguinal, umbilical, femoral, and incisional.
  • Abdominal pain:  intra-abdominal diseases are Present with pain only. The two important features of abdominal pain are that its site and its nature. Clinician mainly diagnoses by having a clear idea on the region where there is pain.
  • Abdominal mass: The common causes of abdominal Masses are: hepatomegaly where liver enlarges. Splenomegaly  where spleen enlarges, hydronephrosis where  kidney enlarges, pseudocyst of pancreas

If you are aware of the anatomy of abdomen then you can distinguish the disorders present in the individual.

Takeaway:

The abdomen is the part of the trunk which lies just below the diaphragm. It is a cylindrical chamber extending from the inferior margin of the thorax to the superior margin of the pelvis and lower limb.

It is margined superiorly by the inferior thoracic aperture and inferiorly by a pelvic inlet which forms two-cavity where the upper part is known as abdomen proper and Lower part is known as the pelvic cavity.

I hope after reading this you have an idea about the anatomy of abdomen. I hope if this article helped you to know more about the anatomy of abdomen do share it.

woms

World of Medical Saviours (WOMS) is a website formed by a group of medicos who are embarking to provide facts, tips and knowledge related to health and lifestyle. This website proves to be a great platform for the medical enthusiast and also for those medicos searching to outgrowth their knowledge about the medical field.

Related Articles

Back to top button