Anatomy Practical Work

Contents

PRACTICAL 1

THE ABDOMINAL CAVITY AND THE PERITONEAL REFLECTIONS.

The aim of this class is to explore the greater sac of the peritoneal cavity, noting

  1. the position of organs covered by peritoneum
  2. the mesenteries, ligaments and omenta which suspend organs from the abdominal wall or connect them to each other
  3. the compartments, spaces, pouches, and recesses of the cavity where air, blood or other body fluids might collect.

By the end of the class you should appreciate how the "essential services" of mobile organs may reach them (via mesenteries, ligaments and omenta) and how the organs may be approached surgically without damaging these folds. You should also appreciate where the lesser sac of the peritoneal cavity lies and how it communicates with the greater sac.

Objectives

1. By the end of this practical and any further necessary study, you should be able to demonstrate and describe the following products of peritoneal folding:

In the abdomen:

In the male pelvis:

In the female pelvis:

2. You should know the positions of the greater and lesser sacs and the supracolic and infracolic compartments of the abdomen.

3. You should be able to define referred pain and outline its mechanisms using examples such as pain originating from the appendix or gall bladder.

Background reading - read the sections in your textbook on:

· the abdominal and pelvic peritoneum

· the greater and lesser sacs

· the general arrangements of the abdominal viscera

You may also find it helpful to look at the sections on the abdominal cavity, peritoneum, lesser omentum and greater omentum in Ackland's DVD Atlas of Human Anatomy DVD 6 (DVD 147 in Health Sciences Library).

It is important that you each explore the peritoneal cavity.

Before beginning the dissection, examine the prosections on display. Identify and locate the following structures:

1. the stomach;

2. the liver and gall bladder;

3. the spleen;

4. the duodenum and pancreas;

5. the kidneys;

6. the jejunum and ileum;

7. the caecum; appendix; ascending, transverse, descending and sigmoid colon; the rectum.

When in situ, which of these organs lie retro-peritoneally on the posterior abdominal wall?

 

 

 

 

The peritoneum.

Parietal peritoneum lines the walls of the abdominal cavity. It clothes the anterior and posterior abdominal walls, the under surface of the diaphragm and the cavity of the pelvis. What is the nerve supply of the parietal peritoneum?

 

 

The visceral peritoneum is continuous with the parietal peritoneum. It leaves the posterior abdominal wall to invest certain viscera. In some cases, it passes in front of the organ (e.g. duodenum), in other cases it leaves the posterior abdominal wall as two leaves lying together to form a mesentery which completely invests the organ (e.g. small intestine). The upper parts of the pelvic organs (rectum, uterus, bladder) project into the abdominal cavity and are therefore covered by visceral peritoneum which hangs down in depressions or pouches between them.

 

The peritoneal cavity.

DISSECTING INSTRUCTIONS – THURSDAY GROUP

The peritoneal cavity should be opened by a cruciate incision:

· A vertical incision just to the right of the midline, from the costal margin to the pubis.

· A horizontal incision through the umbilicus, running laterally on each side for about 10cm.

· The four flaps thus made should be turned outwards.

· When you have finished the practical replace the flaps in their original position.

DISSECTING INSTRUCTIONS – FRIDAY GROUP

Turn the flaps already made outwards, and replace them back at the end of the practical.

The diagram overleaf shows a sagittal section through the abdomen. Use a coloured pen to trace the outline of the peritoneal membrane, then label the structures indicated by pointers.

 

 

 

 

 

Begin by locating and identifying the falciform ligament which runs from the anterior wall of the abdominal cavity to the liver. Its free border contains the ligamentum teres. Of what is the ligamentum teres a remnant?

 

 

Now examine the exposed abdominal viscera within the peritoneal cavity. You must appreciate that the disposition of the viscera within the cavity varies considerably in normal subjects. Also, adhesions may be present, due to pathological processes. What is an adhesion?

It is therefore important that you study as many specimens as possible, both male and female. If adhesions are present, ask for help!

Anterior view of opened peritoneal cavity. Label the structures indicated.

 

Find the greater omentum and the transverse colon attached to its posterior surface. Gently raise the great omentum and transverse colon. You will find that the transverse colon is attached to the posterior abdominal wall by the transverse mesocolon (mesocolic shelf), thereby dividing the abdominal cavity into a supracolic compartment and an infracolic compartment. Label the transverse mesocolon on the diagram of a sagittally sectioned abdomen on the previous page. Note the hepatic and splenic flexures of the colon at the right and left extremities of the transverse mesocolon.

 

The supracolic compartment

This subdivision of the greater sac of the peritoneal cavity lies between the diaphragm above and the transverse mesocolon below. On your specimen, identify the liver and gall bladder, the stomach, duodenum and spleen

Between the liver and the diaphragm is the subphrenic space. Run your hand into this narrow space (from the front) and note that it is divided into right and left parts by the falciform ligament. Your hand is prevented from running right over the top of the liver by the reflection

of peritoneum that connects the liver to the diaphragm. This is the coronary ligament. There is a "bare area" between the liver and diaphragm, bounded by the coronary ligament.

Under the liver you will find the subhepatic channel. Its inferior limit is the transverse mesocolon. On the right, there is a deep, narrow space limited behind by the dorsal abdominal wall and the right kidney. This space is known as the hepato-renal pouch (of Rutherford Morison). Note that it is directly continuous with the right paracolic gutter (see below). The hepato-renal pouch is of surgical importance. Why?

 

 

The diagram below shows a longitudinal section of the abdomen passing through the right lobe of the liver and the right kidney. Label:

The diaphragm The right coronary ligament

The liver The bare area of the liver

The right kidney The hepato-renal pouch

The right subphrenic space

 

Find the stomach and locate the lesser omentum, thin and veil-like, which suspends the lesser curvature of the stomach and the first part of the duodenum from the liver. Identify the free margin of the lesser omentum on its right side. Which three structures are enclosed within the free border of the lesser omentum? Draw a diagram of a transverse section through the free border, showing the relation of these structures to each other.

 

 

 

 

 

 

What is the embryological origin of the lesser omentum? (You should be able to work this out from your notes from the lecture on peritoneal reflections).

 

 

 

 

 

Pass a finger behind the free edge of the lesser omentum. Your finger will enter an opening, the epiploic foramen (of Winslow), which leads into a recess of the peritoneal cavity, situated behind the stomach, the lesser sac (omental bursa). In the following diagram of a sagittal section through the abdomen and pelvis, colour the lesser sac yellow and the greater sac green.

 

 

With your finger in the epiploic foramen, work out what structures form its boundaries, then list them below:

anterior margin:

 

 

 

 

posterior margin:

 

 

 

 

superior margin:

 

 

 

inferior margin:

 

 

 

The diagram below shows a transverse section through the peritoneal cavity at the level of T12 vertebra, showing the arrangement of the peritoneum at the level of the Foramen of Winslow (epiploic foramen). Label the structures indicated.

 

 

 

 

 

 

Locate the greater curvature of the stomach on your specimen. The greater omentum hangs down from the greater curvature. The part of the greater omentum between the greater curvature and the transverse colon is referred to as the gastrocolic ligament.

How many layers of peritoneum make up the greater omentum?

 

You should understand, from your earlier colouring of the greater and lesser sacs, that the (vestigial) space enclosed between the anterior and posterior layers of the greater omentum is part of the lesser sac.

To the left, the greater omentum runs to the spleen, as the gastrosplenic ligament. From the spleen, this same fold continues to the posterior abdominal wall where it attaches in the region of the left kidney, forming the lienorenal ligament. You should have labeled both of these in the above diagram. The splenic artery runs in this latter ligament to reach the spleen.

Identify these ligaments: run your hand into the upper left side of the abdomen and find the spleen. Put your hand between the diaphragm and spleen and gently draw the spleen forwards on its pedicle. Move your hand behind the spleen and you should feel the upper pole of the left kidney. The lienorenal ligament runs between the spleen and kidney.

The infracolic compartment

The infracolic compartment of the greater sac lies below the transverse mesocolon and contains the main mass of intestinal coils. Projecting forwards in the midline is the prominence made by the lumbar vertebrae and the associated psoas muscles. This median "watershed" is flanked on either side by the iliolumbar fossa. The whole cavity is therefore shallowest in the midline and deepest laterally.

Find the beginning of the large intestine in the right iliac fossa. The ascending colon runs upwards to the hepatic flexure, below the liver. The transverse colon runs between hepatic and splenic flexures. Once again, define its mesentery and the greater omentum. The splenic flexure is at a higher level than the hepatic. This is associated with the great bulk of the liver on the right. Find the small transverse fold of peritoneum between the splenic flexure and the diaphragm, the phrenico-colic ligament. Note that there is no phrenicocolic ligament on the right. The descending colon runs vertically down to the pelvic brim where it continues as the sigmoid (pelvic) colon. Find the left and right paracolic gutters on the lateral aspects of the ascending and descending colons.

How do they differ?

 

 

 

 

Make a note of their communications. Why is this clinically important?

 

 

 

 

The small intestine lies in the concavity of the colon and is suspended by the mesentery from the posterior abdominal wall. Confirm that the duodenum has no mesentery. The attachment of the mesentery begins at the duodenojejunal flexure and slopes downwards and to the right sacroiliac joint. The line of attachment of the mesentery to the posterior abdominal wall is termed the root of the mesentery.

Discuss with a demonstrator the paraduodenal fossae. They may be the site of "internal herniae". Explain such herniae.

 

 

 

A more common type of internal hernia is a hiatus hernia. What is this?

 

 

 

 

 

 

Examine the infracolic compartment between the ascending and descending parts of the colon. It is divided into left and right parts by the oblique attachment of the mesentery. The left infracolic compartment communicates with the pelvis. Why is this important?

 

 

 

 

Trace the small intestine to its termination in the right iliac fossa. Locate the caecum and the appendix (if present!). Find the meso-appendix. It contains some important vessels. Which ones?

 

 

 

The pelvic peritoneal cavity is continuous with the abdominal peritoneal cavity. Define the pelvic brim. Trace the sigmoid colon down into the pelvis. It is suspended by the sigmoid mesocolon, which attaches it to the pelvic wall in an inverted "V" arrangement over the division of the left common iliac artery. Locate the rectum. Note that it is retroperitoneal.

In the male, define the upper surface of the bladder. Try to locate the vas deferens, the ureter and the seminal vesicles. Define the rectovesical pouch of the peritoneum.

In the female, define the recto-uterine pouch (of Douglas). Define the uterus, uterine tubes, ovaries and the broad ligament. Find the bladder and the uterovesical pouch.

 

NOTES ON VISCERAL SENSATION

1.Sensation from viscera can be crudely divided into "normal" (usually associated with motility and/or distension) and "abnormal" (i.e. painful).

2.(a) "Normal" sensory information from viscera is transmitted through the visceral sensory fibres that accompany the parasympathetic motor fibres supplying that organ.

What is the parasympathetic motor supply to::

(i) the fore- and midgut?

(ii) the hindgut?

(iii) the bladder?

(b) "Painful" sensory information from viscera is transmitted through the visceral sensory fibres that accompany the sympathetic motor fibres supplying that organ.

What is the sympathetice motor supply to the abdominal and pelvic viscera?

 

 

 

Painful sensations from the viscera are vaguely localised to the median plane, no matter what the location of the viscus.

 

BUT.....

3. All viscera are invested with a layer of the lining of the body cavity, i.e. visceral pleura, pericardium, peritoneum. The sensory supply to this visceral membranous layer is by the visceral sensory fibres described above.

The parietal layers of these membranes are, however, innervated by sensory branches of somatic nerves. Therefore, if the pathology comes to include the parietal membranous layer, the pain now localises well, because it signals through the somatic systems.

Thus, early in acute appendicitis, when only the vermiform appendix and visceral peritoneum are inflamed, pain is felt in the central abdomen; as soon as parietal peritoneum in the right iliac fossa is involved, the pain localises to the fossa. However, one does not experience a pain "in the appendix", or even "in the parietal peritoneum", but in the fossa, i.e. associated with the somatic structures of the abdominal wall.

This phenomenon is known as referred pain. It explains why, for example, cardiac pain is felt in the left arm (among other places); or gall bladder pain in the right shoulder; or ureteric pain in the external genitalia. If you do not understand upon what innervation patterns these particular referrals are based, find out.

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PRACTICAL 2

STOMACH AND MIDGUT.

Objectives

By the end of this practical and any further necessary study you should be able to:

  1. Describe the gross anatomy, understand the function and demonstrate the position and relations of the following structures:
  2. Stomach, duodenum, jejunum, ileum, caecum, appendix, ascending colon and transverse colon (you will revisit the duodenum in a later practical)

  3. Describe the blood supply and lymphatic drainage of the structures listed above.
  4. Relate the blood supply of these structures to their development.
  5. Define the portal venous system and explain its main function.
  6. Define the portosystemic anastomoses; explain their clinical significance and list the main sites at which such anastomoses occur.
  7. Distinguish between sympathetic and parasympathetic nerves in terms of their origin, organisation and function.
  8. Outline the pathways by which autonomic fibres reach the abdominal viscera.
  9. List the sites of referred pain from the stomach, gall bladder, ileum, appendix and colon

 

Before the beginning of the practical, revise the arrangement of the peritoneum.

 

Background reading - read the sections in your textbooks on:

· the abdominal organs

· the arterial supply, venous and lymphatic drainage of the alimentary canal

· the innervation of the gastrointestinal tract

You might also find it useful to look at the sections on the stomach, small intestine, large intestine and abdominal vessels in Acland's DVD Atlas of Human Anatomy, DVD6 (DVD 147 in the Health Sciences Library).

 

Lesser sac and stomach.

DISSECTING INSTRUCTIONS - THURSDAY GROUP

Lesser sac, stomach and coeliac trunk.

· Find the gastrocolic ligament ie. that part of the greater omentum running to the transverse colon.

· Make an incision, about 8cm long, through it about 2.5cm away from and parallel with the greater curvature of the stomach. If you cut closer to the stomach than this, you will destroy the blood supply to the greater curvature.

The lesser sac is now open. Pass a hand through the incision, behind the stomach into the lesser sac. Pass a finger of the other hand through the foramen of Winslow and make contact. Define the boundaries of the lesser sac. Behind the stomach, on the posterior abdominal wall, identify the following:

the pancreas;

the splenic artery;

the left kidney and adrenal gland.

The stomach is a muscular bag, fixed at both ends, much of which lies under cover of the lower ribs. Label the structures indicated by pointers in the following diagram of the stomach:

 

 

 

DISSECTING INSTRUCTIONS - THURSDAY GROUP

The stomach and coeliac trunk.

· Carefully cut through the costal margin just lateral to the xiphoid process and make a small incision in the diaphragm. This should give you a clear view of the oesophagus and cardiac region of the stomach.

· Working mainly with forceps, dissect the lesser omentum in the cardiac region and locate left gastric artery. Trace this back to its origin from the coeliac trunk, removing the lesser omentum as necessary to do so.

· Expose the coeliac trunk and trace its other branches. DO NOT cut through the structures lying in the free border of the lesser omentum.

On the stomach identify the following structures that you labeled in the preceding diagram:

cardiac orifice;

fundus;

body;

pyloric antrum and pylorus;

 

Is the cardiac orifice an "anatomical" sphincter?

 

Is the pylorus an "anatomical" sphincter?

 

 

At what vertebral level does the pylorus normally lie? This is the level of the "transpyloric plane".

 

 

 

Now find the greater and lesser curvatures. Clean and identify the blood vessels closely related to these two curvatures.

Concentrate on the lesser curvature (both anterior and posterior surfaces). Branches of the anterior (left) and posterior (right) vagus may be seen sinking into the muscular wall of the stomach.

How does the left vagus come to lie anteriorly on the stomach and the right vagus posteriorly?

 

 

 

 

Study the relations of the stomach. Name at least six.

 

 

 

 

What is a hiatus hernia? How does it differ from a congenital diaphragmatic hernia?

 

 

 

Arterial supply of the gastrointestinal tract.

Three arteries leave the aorta and pass ventrally to supply the gastrointestinal tract. The most cranial one, the coeliac trunk, supplies the foregut and its two derivatives (liver, pancreas) and the spleen. The second one, the superior mesenteric, passes within the mesentery to supply the midgut. The last one, the inferior mesenteric, runs into the transverse mesocolon to supply the hindgut. This latter vessel will be considered in the next practical.

The coeliac trunk.

This is the artery of the foregut, and its three branches supply the gastrointestinal tract down to the opening of the common bile duct into the duodenum, plus the liver, spleen and pancreas.

Label the diagram of the coeliac trunk and its branches below.

 

Define the coeliac trunk in your cadaver as it arises from the aorta, at the upper border of the pancreas.

At what vertebral level is the coeliac trunk given off?

 

Note the coeliac ganglia. They lie on each side of the coeliac trunk. They form the "hub" of the autonomic nerve supply to the abdominal viscera.

Locate the three branches of the coeliac trunk. The left gastric artery enters the lesser omentum and runs along the lesser curvature of the stomach. Find the splenic artery as it runs to the left, along the upper border of the pancreas. Look for the hepatic artery as it passes downwards and to the right behind the peritoneum of the posterior abdominal wall before entering the lesser omentum. You will study the distribution of the splenic and hepatic arteries in detail in later practicals.

List the main branches arising from these three arteries and make sure you know their course and distribution.

 

 

 

 

 

 

 

 

 

The superior mesenteric artery

Superior mesenteric artery supplies the midgut. List the components of the midgut.

 

 

 

 

 

Look at the general disposition of these structures by displacing the greater omentum and transverse colon superiorly. Displace the small bowel to the left of the midline and examine it. Starting from the duodeno-jejunal junction follow the jejunum and the ileum to the start of the large bowel. Note that there is no macroscopic demarcation between jejunum and ileum. The bowel does, however, change its character from above downwards. With the help of the diagrams overleaf, list below five points that will enable a surgeon to determine the level of a loop of small intestine during an operation.

 

 

 

What is Meckel’s diverticulum? It is present in only about 2% of the population. Is it present in your specimen?

 

 

 

Next study the large bowel. It can easily be distinguished from small bowel by:

What is diverticulosis?

 

What is diverticulitis?

 

 

Now concentrate on the area of the ileocaecal junction and appendix. Make sure you know this region well. Bear in mind that the first operation you will probably perform might be an appendicectomy.

Find the caecum. It is the blind pouch of large bowel that projects downwards from the beginning of the ascending colon, below the ileocaecal junction. Its posterior wall may be firmly attached to the posterior wall of the right iliac fossa or, more commonly, separated from it by a retrocaecal fossa which can extend as far up as the liver.

The vermiform appendix is attached to the posteromedial wall of the caecum, below the ileo-caecal junction. The three taeniae coli merge at the root of the appendix. Its length and position varies considerably. Compare the appendices of the cadavers on all the neighbouring tables. Identify the mesoappendix. This is the mesentery of the appendix; the appendicular artery runs in it. Where does this artery originate?

 

 

 

ACUTE APPENDICITIS

A common abdominal condition. Pain usually begins as para-umbilical discomfort, accompanied by malaise, and diarrhoea or constipation. (It is dangerous to use laxatives in cases of suspected appendicitis: vigorous contraction of the gut wall often ruptures the inflamed appendix, precipitating peritonitis). The temperature is usually raised. Within 24-48 hours the pain refers to the right iliac fossa. The site of maximum tenderness (which is pain elicited by the probings of the examiner) is at McBurney’s point, which is the surface marking of the appendix. This lies at the junction of the lateral one-third with the medial two-thirds of a line joining the anterior superior iliac spine to the umbilicus. In 65% of adults the appendix is retro-caecal; in 25% it hangs over the pelvic brim.

Pus from an appendix abscess can track upwards in the right paracolic gutter to reach the subphrenic space (between the thoracic diaphragm and liver). Referred pain in the right shoulder ensues.

The appendix is removed through an incision centred on McBurney’s point. A more or less horizontal skin incision is favoured, to follow the crease lines and therefore the dermal stress lines. Each succeeding layer of aponeurosis/muscle is then split parallel to the direction of its fibres. The caecum is delivered through the incision and the root of the appendix found by tracing the taeniae coli. A long retro-caecal appendix may also be retro-colic (retroperitoneal behind the ascending colon) and a second incision may be required to gain proper access so as to mobilize the colon to remove the appendix intact. The colon is most easily freed from its lateral side. Why?

 

 

Examine the ascending colon. It runs from the right iliac fossa to the hepatic flexure under the right lobe of the liver. From the hepatic flexure, the transverse colon runs almost horizontally to the splenic flexure, invested in its mesentery, the transverse mesocolon. The descending colon, extends from the splenic flexure to the pelvic brim, where it acquires a mesentery (the sigmoid mesocolon) and becomes the sigmoid colon. The rectum will be studied together with the other structures in the pelvis.

 

DISSECTING INSTRUCTIONS - THURSDAY GROUP

The small intestine and superior mesenteric artery.

· Look for the superior mesenteric artery as it descends over the third part of the duodenum (the vein lies on its right side).

· With forceps and fingers, carefully peel away the anterior layer of the mesentery to help you identify and clean the following arterial branches: jejunal, ileal, ileo-colic, right and middle colic. They are accompanied by corresponding veins.

· Don't worry if you don't have time to complete this task. Leave what you don't manage to the Friday group - but remember to identify the vessels they uncover in your next class.

DISSECTING INSTRUCTIONS - FRIDAY GROUP

The small intestine and superior mesenteric artery.

    • Identify the superior mesenteric artery and its jejunal, ileal, ileo-colic, right and middle colic branches. Identify also their accompanying veins.
    • Identify the duodeno-jejunal junctions. Just distal to this, make a longditudinal incision, 5 - 10 cm long in the wall of the jejunum. Remove any contents and examine its interior.
    • make a similar incision in the wall of the distal ileum and examine its interior. Compare/contrast it with the interior of the jejunum.

 

The superior mesenteric artery arises from the front of the aorta about one centimetre below the origin of the coeliac trunk. At what vertebral level is the superior mesenteric artery given off?

 

 

 

Locate the superior mesenteric artery as it descends over the third part of the duodenum. Its first branch is the inferior pancreatico-duodenal artery. Where does the superior pancreatico-duodenal artery come from?

From which side of the superior mesenteric artery do the following vessels arise

· jejunal;

· ileal;

· ileocolic;

· right colic;

· middle colic.

Make sure you know the course and distribution of these important vessels.

Complete the labelling of the following diagram:

Branches of the superior mesenteric artery:

 

 

 

 

 

The artery of the hindgut is the inferior mesenteric artery. You will study this vessel in the next class.

Venous drainage of the gastrointestinal tract.

It is convenient to study the venous return with the arterial supply as the two are essentially similar. The vessels draining the foregut and its derivatives ultimately drain into the portal vein. They roughly correspond to the arteries of the foregut. Remember that the portal vein runs in the free edge of the lesser omentum.

The oesophageal veins are important. Why?

 

 

 

The venous drainage of the midgut is quite regular. Each branch of the superior mesenteric artery is accompanied by a vein. All these veins ultimately flow into the superior mesenteric vein, a large trunk which lies to the right of the artery. Locate this vessel on the dissection. Confirm that it receives the splenic vein behind the neck of the pancreas. Here, the superior mesenteric vein acquires a new name, the portal vein. Note that it is named portal vein above and superior mesenteric vein below the level of entry of the splenic vein, but the two represent a single continuous trunk. As you will see in the next class, the inferior mesenteric vein receives tributaries identical to the branches of the inferior mesenteric artery. The vein runs vertically upwards and usually joins the splenic vein, behind the body of the pancreas, just before the union of the splenic vein with superior mesenteric vein.

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What is the destination of the portal vein?

 

 

What is the purpose of the portal circulation?

 

 

 

 

What anastomoses exist between the portal and systemic venous systems?

 

 

 

 

 

 

 

 

What is their clinical significance?

 

 

 

 

 

 

Label the structures indicated in the diagram below, which shows the formation of the portal vein behind the neck of the pancreas (this part of the pancreas has been removed in the diagram).

 

 

 

 

 

 

 

Lymph drainage of the gastrointestinal tract.

Why is knowledge of the lymphatic drainage of the gastrointestinal tract important?

 

 

 

 

Make sure that you know the general pattern first, and then learn the lymph drainage of the individual abdominal organs. Discuss this topic with the demonstrators and read about it in your textbooks.

From virtually the whole length of the gastrointestinal tract the lymph vessels pass back along the course of the arteries to lymph nodes that lie in front of the aorta at the origins of the coeliac, superior and inferior mesenteric arteries. These are called the coeliac, superior and inferior mesenteric groups of lymph nodes. Hence if you know the arterial supply to the

gastrointestinal tract and its associated glands, you almost always know its lymphatic drainage. The exception to this general rule is the rectum. Although the major artery of the rectum is the superior rectal branch of the inferior mesenteric artery, lymph also follows the middle rectal artery to the internal iliac lymph nodes. (You will consider this further when you study pelvis in year 3).

The coeliac, superior mesenteric and inferior mesenteric lymph nodes are also termed pre-aortic nodes. They drain into each other from below upwards, the coeliac group itself draining into the cisterna chyli.

Which lymphatic channel originates from the cisterna chyli? Where does this channel run and where does it empty its contents?

 

 

 

 

 

Attempt to explain why abdominal malignant disease may sometimes lead to enlargement of supraclavicular lymph nodes on the left side (think about this rather than searching through textbooks).

 

 

 

 

The pre-aortic nodes are the last in a series of lymph node "filters" that lie between the mucous membrane of the gut and the cisterna chyli.

The first filtering mechanism consists of isolated lymphatic follicles which lie in the mucous membrane of the alimentary canal. What are Peyer's patches?

 

 

 

 

From the follicles lymph drains to nodes that lie in the peritoneal attachments at the margins of the intestine and from there to nodes that are found halfway between the gut and the aorta. Finally lymph will drain into the pre-aortic nodes.

 

Nerve supply of the gastrointestinal tract.

All parts of the gut and its derivatives are innervated by parasympathetic and sympathetic nerves. These fibres modify the activity of the intrinsic nerve plexuses of the gut. Revise the basic anatomy of the autonomic nervous system.

In which layers of the gut wall are the intrinsic (myenteric) nerve plexuses located?

 

 

Most of the autonomic fibres to the gut travel via the coeliac plexus, which is located around the coeliac trunk, although the parasympathetic fibres to the hindgut (which originate from sacral segments of the spinal cord) travel via the inferior hypogastric (pelvic) plexus.

The coeliac plexus receives its parasympathetic input from the two vagus nerves. What is their function?

 

 

 

The sympathetic contribution to the coeliac plexus is from the splanchnic nerves. What is their function?

 

 

 

 

You may have seen the splanchnic nerves during your dissection of the thorax. Where do they arise? How do they reach the abdomen?

 

 

 

By now you should be absolutely clear what is meant by the term "referred pain".

Where would a patient feel pain referred from

To which of these three areas is pain from the appendix referred?

Pain from the gall bladder is sometimes referred to the shoulder. Attempt to explain this. Discuss your ideas with a colleague and/or demonstrator if you are unsure.

Remember there is a formative MCQ on the Nathan Bodington building that will help you assess your learning of the material covered in this class.

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PRACTICAL 3

THE HINDGUT. THE LIVER, GALL BLADDER AND BILIARY TREE.

Objectives

By the end of this practical and any further necessary study (including revision of the material covered in the previous practical) you should be able to:

  1. Describe the gross anatomy, understand the function and describe the position and relations of the following structures:
  2. Ascending colon, transverse colon, descending colon, sigmoid colon, liver, gall bladder and biliary system.

  3. Describe the blood supply and lymphatic drainage of the structures listed above.
  4. Outline the venous drainage of the whole gastrointestinal tract.
  5. Outline the lymphatic drainage of the whole gastrointestinal tract.
  6. Describe the flow of blood through the liver and outline the effects of obstructing this flow.
  7. Describe the flow of bile from the liver and outline the effects of obstructing this flow.

 

 

Background reading - read the sections in your textbooks on:

You might also find it useful to look at the section on liver and pancreas and that on the abdominal vessels in Acland's DVD Atlas of Human Anatomy, DVD6 (DVD 147 in the Health Sciences Library).

The inferior mesenteric artery

The inferior mesenteric artery is the artery of the hindgut . It supplies the gut from the splenic flexure up to and including the rectum. At what vertebral level is the inferior mesenteric artery given off?

 

 

DISSECTING INSTRUCTIONS - THURSDAY AND FRIDAY GROUPS

The large intestine and inferior mesenteric artery

· Strip the peritoneum off the dorsal abdominal wall between the descending colon and the root of the mesentery to find the inferior mesenteric artery at its point of origin from the abdominal aorta

· Identify and dissect the left colic artery and sigmoid branches.

· Make a longditudinal incision in the lateral wall of a short length of colon (try to find a 5 to 10cm section that is relatively empty). Remove any contents and examine its internal structure.

 

 

Label the main branches of the inferior mesenteric artery shown in the diagram below. Make sure you know the course and distribution of these branches.

 

 

 

What is the marginal artery? Which vessels contribute to it? What does it supply?

Attempt to explain why ligation or removal of inferior mesenteric artery ( the latter may occur when an aortic aneurysm is repaired) does not impair gut function.

 

Record your observations of the internal structure of the colon.

 

The liver, gall bladder and biliary system.

DISSECTING INSTRUCTIONS. THURSDAY GROUP

The liver and gall bladder

· Locate the free border of the lesser omentum. Strip off the peritoneum and by blunt dissection identify: the common bile duct, the hepatic artery, the portal vein.

· Cut through the above structures midway along the free edge of the lesser omentum.

· Sever the falciform ligament (ask for help from the demonstrators if necessary).

· Cut the anterior layer of the left and right coronary ligaments.

· Working from behind, break through the posterior edge of the left and right coronary ligaments.

· With the help of a demonstrator divide the inferior vena cava so as to leave its posterior wall on the dorsal abdominal wall and its anterior wall in the liver (sometimes the inferior vena cava is entirely embedded in the liver).

· Remove the liver from the cadaver.

· Remember to replace the liver in the abdomen at the end of the class, so that it can be studied by the Friday group.

Consider the relations of the liver and complete the labelling on the following diagram of the posterior aspect of the liver:

Look at the liver and revise its peritoneal reflections. Define the following:

What structure is found in the free edge of the falciform ligament?

 

 

Locate the porta hepatis and name the structures going through it.

 

 

On the posterior surface of the liver identify the inferior vena cava. Venous blood leaves the liver through the three (usually) hepatic veins. These veins provide partial support (anchoring) to the liver.

Name two other factors that will contribute to the support of the liver.

 

 

The liver has four anatomical lobes. Identify the left and right lobes, which are separated by the falciform ligament. The right is the larger of the two. The anatomical right lobe incorporates the quadrate and caudate lobes on the postero-inferior aspect of the liver. Identify these two additional lobes.

These anatomical lobes of the liver do not correspond with the functional lobes. Functionally, the right and left lobes are defined according to their blood supply. The right branch of the hepatic artery and the right branch of the portal vein supply the right functional lobe, their left branches supply the left functional lobe. Each functional lobe is drained by its own hepatic duct and has its own venous drainage. The functional lobes are further subdivided into segments, each with distinct blood supply and biliary drainage.

 

Discuss with a demonstrator the surgical significance of this segmentation of the liver.

 

 

 

 

 

 

Examine the gall bladder. It is usually firmly attached to the underside of the liver. Identify the fundus, body and neck. The narrow neck gives way to the cystic duct. What is the function of the gall bladder?

 

 

 

The biliary system

Bile is manufactured by the liver cells. It is collected into microscopic canaliculi. These will eventually drain into the left and right hepatic ducts. These join (usually at the porta

hepatis) to form the common hepatic duct. This in turn is joined by the cystic duct to form the common bile duct. At this stage, remind yourself of the structures that run in the free edge of the lesser omentum. What is their relationship one to another?

 

Where does the common bile duct run after it leaves the edge of the lesser omentum?

 

 

 

 

 

What and where is the sphincter of Oddi?

 

 

Complete the labelling on the following diagram:

 

 

 

If a gallstone became lodged at the sphincter of Oddi, which other organ would be affected?

 

Why do patients with biliary obstruction appear yellow? Such patients also have pale faeces and dark urine. Why?

 

 

 

 

 

 

 

What is the blood supply of the gall bladder? Where does it come from?

 

 

Learn the blood supply, venous drainage, lymphatic drainage and innervation of the liver and gall bladder.

There is a formative MCQ relating to this practical available on the Nathan Bodington building.

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PRACTICAL 4

THE DUODENUM, PANCREAS AND SPLEEN.

Objectives

By the end of this practical and any further necessary study you should be able to:

    1. Describe the gross anatomy, understand the function and describe the position and relations of the following structures:
    2. Duodenum, pancreas and spleen.

    3. .Describe the blood supply and lymphatic drainage of these structures
    4. List the main branches of the abdominal aorta and outline their distribution.
    5. Outline the arrangement of the main veins of the abdomen.
    6.  

      Background reading – read the sections in your textbooks on

      • Duodenum
      • Pancreas
      • Spleen
      • The vessels of the posterior abdominal wall

    You might also find it useful to look at the sections on the duodenum (at the start of the small intestine section), the pancreas and spleen and the abdominal vessels in Acland's DVD Atlas of Human Anatomy, DVD6 (DVD 147 in the Health Sciences Library).

     

     

    The duodenum and pancreas.

    Clean the remains of the transverse mesocolon from the anterior aspects of the duodenum and pancreas then examine the duodenum. The initial 2.5cm lies within peritoneum, the rest is completely retroperitoneal. It consists of four parts. Appreciation of the directions of the four parts is important. Identify and describe the various parts. Make a note of their direction and the verebral level of each part:

    First part:

     

    Second part:

     

    Third part:

     

    Fourth part:

     

     

    Label the diagram below which shows the duodenum and pancreas with their peritoneal covering still in place. Indicate on the diagram the positions of the four parts of the duodenum:

     

     

     

     

     

    The duodenum terminates at the duodeno-jejunal flexure. There is no distinction between the duodenum and jejunum apart from the peritoneal arrangement: the duodenum is retroperitoneal, the jejunum has a mesentery.

    The pancreas is a soft, lobulated gland lying immediately behind the peritoneum of the posterior abdominal wall. The transverse mesocolon is attached to its anterior surface, just above the inferior border. It consists of a head, neck, body and tail. The lower part of the head is prolonged to the left, behind the superior mesenteric artery and vein, in front of the aorta. This is the uncinate process. Label the parts of the pancreas in the diagram below then identify them on you dissection.

    .

     

     

     

    Which vein is formed behind the neck of the pancreas?

     

    The tail of the pancreas passes in the lienorenal ligament to reach the spleen. The splenic artery follows a wiggly course along the upper border of the pancreatic body and tail. Locate this vessel on your specimen.

     

     

    DISSECTING INSTRUCTIONS. THURSDAY GROUP

    The duodenum and pancreas.

    · Hold the tail of the pancreas with the splenic vessels and the spleen and pull forwards to mobilise the body of the pancreas.

    · Look for the inferior mesenteric vein joining the splenic vein.

    · Identify the point at which the splenic and superior mesenteric veins unite to form the portal vein, then replace the body of the pancreas and spleen on the posterior abdominal wall.

    · Mobilise the descending part of the duodenum and the head of the pancreas by cutting through the peritoneum at the right border of duodenum. Turn them together to the left, so that you are looking at their posterior surface.

    · Do not completely detach the pancreas and duodenum, or the Friday group will be disorientated!

    · Identify and very carefully clean the common bile duct, tracing it from its cut end (where it traveled in the free edge of the lesser omentum) to the point at which it enters the second part of the duodenum.

    · Open the first and second parts of the duodenum along their posterior surface and try to locate the duodenal papilla on the posteromedial wall of the second part, about 10cm from the pylorus.

    · When you finish the practical, replace all the structures back in the anatomical position so they can be studied by the Friday group.

    DISSECTING INSTRUCTIONS. FRIDAY GROUP

    The duodenum and pancreas.

    · Hold the tail of the pancreas with the splenic vessels and the spleen and pull forwards.

    · Identify the inferior mesenteric vein joining the splenic vein.

    · Identify the point at which the splenic and superior mesenteric veins unite to form the portal vein.

    · Detach the body of the pancreas from the posterior abdominal wall and cut the splenic artery near its origin.

    · Detach the head and neck of the pancreas with the duodenum and associated structures (bile duct, portal vein)

    · Remove the duodenum, pancreas and spleen in one piece.

    On the posterior surface of your isolated specimen, trace the common bile duct from its cut end (where it travelled in the free edge of the lesser omentum) to the point at which it enters the second part of the duodenum.

    · Try to locate the duodenal papilla on the posteromedial wall of the opened second part of the duodenum, about 10cm from the pylorus.

    · Detach and study the spleen.

     

    The pancreas has both endocrine and exocrine components. The exocrine component is responsible for the secretion of various digestive enzymes. These are collected into a series of ducts which, in turn, open into a principal pancreatic duct. The pancreatic duct joins the common bile duct to form the ampulla of Vater. The ampulla opens in the duodenum, at the

    duodenal papilla. The accessory pancreatic duct (draining the uncinate process) also opens in the duodenum, about 2cm proximal to the duodenal papilla.

    The duodenal papilla marks the boundary between which two subdivisions of the gut?

     

     

    Complete the labelling of the diagram below:

    View of the gall bladder and the associated duct system opening into the duodenum.

     

     

     

    What is the blood supply of the pancreas?

     

     

    What are the important relations of the pancreas?

     

     

     

     

     

     

    What effects might you expect from a carcinoma of the head of the pancreas?

     

     

    Why is this condition often inoperable?

     

     

    The spleen.

    Examine the spleen. It lies beneath the costal margin, in the left hypochondrium. To which ribs is it related?

     

    The hilum of the spleen lies at the level of L1 vertebra ie. in the transpyloric plane.

    Try to orientate the spleen. Its antero-superior border is notched. It has an outer convexity which lies against the diaphragm and a hilum that lies in the angle between the stomach and the left kidney. The splenic artery reaches the hilum where it divides into four or five branches before entering the spleen. Branches from the splenic artery supply the stomach. Which ones?

     

     

     

    Name the important relations of the spleen and revise its peritoneal attachments.

     

     

     

     

     

     

     

     

    Finally, replace all the abdominal viscera in situ. Make a "mental picture" of all the organs, their relations and peritoneal reflections. Revise the major vessels and their branches. Labelling the following diagrams may help in this latter task.

     

     

    Between which vertebral levels does the abdominal aorta extend?

     

     

     

     

     

     

     

     

    Branches of the abdominal aorta:

    Tributaries of inferior vena cava:

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    SELF DIRECTED LEARNING - LIVING ANATOMY

    THE ABDOMINAL WALLS AND ABDOMINAL VISCERA.

    OBJECTIVES

    After completing this practical, you should be able to carry out the following on a living subject:

    1. Use appropriate landmarks to mark and demonstrate the named regions of the abdominal walls.
    2. 2. Use appropriate landmarks to locate (and demonstrate) the positions of the following intra-abdominal structures; outline the variations caused by physique, posture, breathing and fullness:

      Liver Stomach

      Gall bladder Duodenum

      Spleen Pancreas

      Root of the mesentery Appendix

      Colon L and R kidneys

       

       

      Abdominal regions

      For descriptive purposes, the abdomen is divided into four quadrants or nine regions, usually projected onto the anterior abdominal wall. These are used in clinical practice to describe the sites of abnormal features such as masses, tenderness, reported pains etc. It is important to know what organs can be expected to occupy each region - a mass in the right upper quadrant, for example, cannot arise from the bladder.

      The quadrants are centred on the umbilicus. They and their contents are illustrated on the adjacent page. Unfortunately the position of the umbilicus is variable, and depends greatly

      on the condition of the anterior abdominal wall. Nevertheless, in modern clinical practice, the abdomen is normally divided into quadrants.

      The nine regions are created by intersections between two horizontal and two vertical planes. Strictly these are:

      Horizontal: the transpyloric plane

      the transtubercular plane

      Vertical: the left and right lateral lines

      The transpyloric plane (so called because it cuts through the pylorus) lies midway between the sternal notch and the upper border of the pubic symphysis, at the level of L1 vertebra. The transtubercular plane passes through the iliac tubercles (the iliac tubercle lies on the iliac crest, forming the most lateral part of the bony pelvis), at the level of L3 vertebra.

      The lateral lines are the midclavicular planes, each of which also passes through the ipsilateral mid-inguinal point.

      In fact, in clinical practice, the nine abdominal regions are defined imprecisely. For example, a clinician would not run a tape measure from sternal notch to pubis to define the transpyloric plane. Instead, a horizontal line crossing the costal margins in the mid clavicular line is taken to mark the transpyloric plane, (and sometimes the subcostal plane is substituted for the transpyloric plane).

      THE ABDOMINAL QUADRANTS

       

       

       

       

       

       

       

      UPPER

      RIGHT

      Liver

      Gall bladder (fundus at tip of 9th costal cartilage, where lateral border of rectus abdominis muscle crosses costal margin).

      Kidney and suprarenal gland

      Colon – hepatic flexure and right transverse

      Duodenum with head of pancreas (part).

      Small intestine

      LEFT

      Stomach

      Spleen

      Pancreas

      Kidney and suprarenal gland

      Colon – splenic flexure and left transverse

       

       

       

      Small intestine (jejunum)

       

       

      LOWER

       

      Colon – ascending

      Caecum

      Appendix (including McBurney’s point)

      Small intestine (ileum)

       

      Colon – descending and

      Sigmoid

       

       

       

      Small intestine

       

      Is the liver palpable in a normal subject?

      Is the spleen palpable in a normal subject?

      The gastrointestinal tract is normally impalpable, although parts of the colon can often be palpated if only mildly pathological eg. the sigmoid colon in chronic constipation. Other retroperitoneal structures (kidney, pancreas, great vessels) are impalpable unless enlarged, although kidneys and the abdominal aortic pulse may be felt in very thin people.

      Follow these instructions to subdivide your own (or a consenting colleague’s) abdomen into the nine regions:

      1. Identify the costal margin, iliac crest and anterior superior iliac spine.

    3. Identify the pubic tubercle, which can be palpated through clothing on the superior border of the pubis 2-3cm from the midline. Bisect the line joining this to the anterior superior iliac spine to find the mid-inguinal point.

    3. Lightly mark a horizontal line on the anterior abdominal wall such that the line crosses the costal margin in the mid clavicular line on each side (ie. where the lateral border of rectus abdominis muscle crosses the costal margin on each side) . The horizontal line marks the transpyloric plane.

    4. Palpate the iliac crest between the mid-axillary line and the anterior superior iliac spine to find the projecting lip called the iliac tubercle. Draw a horizontal line connecting the two iliac tubercles (the intertubercular plane).

    5. On each side draw a vertical line on the abdomen which, if extended both ways, would cross the mid-clavicular and mid-inguinal points.

    The most commonly used names for these abdominal regions are:

    R. HYPOCHONDRIAC EPIGASTRIC L. HYPOCHONDRIAC

    R. LUMBAR UMBILICAL L. LUMBAR

    R. ILIAC HYPOGASTRIC L. ILIAC

    (pubic)

    Draw the dividing lines on the diagram of the anterior abdominal wall below and label each region

    THE ABDOMINAL REGIONS

    RIGHT HYPOCHONDRIAL REGION

    Liver and Gall bladder

    (Kidney) and suprarenal gland

    Colon – hepatic flexure

    EPIGASTRIC REGION

     

    Liver

    (Transverse colon)

    Abdominal aorta and vena cava

     

     

     

    Pylorus and

    LEFT HYPOCHONDRIAL REGION

    Stomach

    Spleen

    (Kidney) and Suprarenal gland

    Colon – splenic flexure

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    Transpyloric

    RIGHT LUMBAR REGION

    Kidney

    Colon – ascending

     

     

     

    Small intestine

    Duodenum (1st part)

    UMBILICAL REGION

    (Transverse colon)

    Duodenum and pancreas

    Abdominal aorta and vena cava

    Small intestine

    Iliac vessels

    LEFT LUMBAR REGION

    Kidney

    Colon – descending

    Pancreas

     

    Small intestine (jejunum)

    plane

     

     

     

     

     

     

     

     

     

     

    Transtubercular

    RIGHT ILIAC REGION

     

    Caecum

    Appendix

    Small intestine (ileum)

    HYPOGASTRIC REGION

    Distensible organs of the pelvis eg. bladder in infants or in adults when full; uterus after 12th week of pregnancy.

    Small intestine

    Iliac vessels

    Spermatic cords

    LEFT ILIAC REGION

     

    Sigmoid colon

    Small intestine

    plane

     

    The contents of the nine abdominal regions are shown on the adjacent page.

    Soft tissue features of anterior abdominal wall

    1. The umbilicus is found (unsurprisingly) in the umbilical region of the anterior abdominal wall, though its level is variable.

    2. The anterior abdominal muscles as a whole can be tensed by attempting to breathe out against a closed glottis. Palpate them under these conditions and during normal breathing.

     

    Positions of the visceral organs

    On yourself (with the aid of a mirror), or on your consenting colleague, identify and mark the following:

    1. The liver occupies most of the right hypochondrium and epigastrium. Its upper border (in mid-respiration) is marked by a line from the right 5th rib and costal cartilage across the lower end of the sternum to the left 5th intercostal space in the mid-clavicular line. The lower border runs from here to the costal margin in the right mid-axillary line.

    1. The gall bladder: lies at the tip of the 9th costal cartilage on the right; this is best recognised as the point at which the lateral border of the right rectus abdominis muscle crosses the costal margin. This intersection lies on the transpyloric plane.

    Find out about rectus abdominis. What are its attachments? What is its function? What name is given to its lateral border?

     

     

     

     

     

     

     

     

    3. Stomach: the most consistently placed part is the pylorus, which in the supine subject lies on the transpyloric plane. However, the pylorus descends several cms on standing up. Most of the rest of the stomach lies above and to the left of the pyloric position, and the fundus may lie as high as the fifth rib in the left mid-clavicular line. (Note that the transpyloric plane also marks the position of the gall bladder, the renal hila, the hilum of the spleen and the origin of superior mesenteric artery).

    4. Duodenum and pancreas: the head of the pancreas lies just below and right of the pyloric position; the duodenum curves from the pylorus rightward, downward and leftward (the 1st-3rd parts), the ascends leftward (the 4th part) to reach the transpyloric plane a few cms to the left of the midline.

    5. The appendix: the most constant part of the appendix is its base, which is approximately McBurney's point: this point lies 2/3 of the way along a line joining the umbilicus to the right anterior superior iliac spine.

    6. The mesentery: its root is attached to the posterior abdominal wall along a line extending from the end of the 4th part of the duodenum (on or just below the transpyloric plane, a few cms to the left of the midline) to McBurney's point.

    7. The colon: the ascending colon rises from McBurney's point to the transpyloric plane ; the transverse colon hangs down to umbilical level then rises to the left lumbar regions; the sigmoid colon crosses to the centre of the hypogastric area.

    8. The spleen: lies between the left 9th and 11th ribs between the erector spinae muscles and the mid-axillary line (separated from the rib cage by the diaphragm and the costodiaphragmatic recess of the pleura).

    9. The kidneys: in a supine subject the hila of the kidneys lie at about the transpyloric plane, the right kidney slightly lower than the left. In adults the medial borders of the kidneys are 4-5cms from the midline at the hilum, a bit less above and a bit more below. The upper poles are covered posteriorly by the 11th and 12th ribs, and the lower poles are 3-4cms above the iliac crests. These positions may drop by 5cm or more on standing as the kidneys are embedded in very soft perinephric fat. The ureters descend almost vertically from the hila into the iliac fossae.

     

    Palpable abdominal organs

    Visual inspection precedes palpation. The abdominal wall normally moves freely with respiration. In thin subjects, the pulsations of the abdominal aorta are transmitted to the anterior abdominal wall and are easily seen. Movements of the gastrointestinal tract are rarely visible.

    The ease with which intra-abdominal structures can be palpated felt depends on the physique of the subject and the experience of the examiner. You should however be able to do the following.

    1. Abdominal aorta: can be felt pulsing powerfully by lumbar vertebral bodies just to the left of the midline.

    2. Descending colon: may often be felt in the left lumbar region because of the relative solidity of its contents.

    3. Kidneys: in a supine subject, squeeze the flank region firmly between the hands, one posteriorly and the other anterolaterally, and feel for downward movement of the kidney as the subject breathes in. Most likely to succeed in a slim subject.

    Palpation of other organs is not normally possible in the healthy adult, but note the following:

    The liver. Is palpable in the infant, its antero-inferior edge extending beyond the right costal margin out of the right hypochondrium.

    The spleen. The normal spleen can be palpated in the infant as a mass descending from the left hypochondrium, moving with respiration. In the adult, it cannot be felt until about three times its normal size.

    The gastrointestinal tract is normally impalpable. In chronic constipation, the sigmoid colon, packed with faeces, can be felt in the left iliac fossa. The caecum and sigmoid colon, if enlarged by chronic inflammation, can be palpated in the right and left iliac fossae respectively.

    The uterus and ovaries. Masses rising upwards into either of the iliac fossae or the hypogastrium are of pelvic origin. The female genital tract is a common source, e.g. cancer of the body of the uterus, or uterine fibroids, or masses arising in the ovaries. In pregnancy, the uterus is not palpable through the anterior abdominal wall until after the 12th week.

    The urinary bladder is an abdominal organ in the infant and therefore readily palpable in the hypogastrium when full. In the adult a completely full bladder (200-300ml) is theoretically palpable above the pubis. Well-developed rectus abdominis muscles make this difficult (remember the inferior linea alba is very narrow), but suprapubic puncture of the distended bladder is possible. When done properly, the puncture does not penetrate the peritoneal cavity. Why not?

    Remember to complete the final formative MCQ, covering the material of the last gross anatomy practical class and this living anatomy exercise that is available on the Nathan Bodington building.

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    Study Guide
    Practical 1
    Practical 2
    Practical 3
    Practical 4
    Living anatomy
    Imaging