Living Anatomy of the Abdomen Flashcards
Where does the superior margin of the abdominal wall pass from?
From the xiphoid process, along the costal margins to the 12th rib posteriorly.
Where does the inferior margin of the abdominal wall pass?
From the pubic tubercle and crest, along the inguinal ligament to the anterior superior iliac spine (ASIS
What abdominal organs are protected by the thoracic cage?
- Liver
- Spleen
- Stomach (cardia and fundus)
- Kidneys (superior poles)
The linea alba and linea semilunaris mark the boundaries of what structure?
Medial and lateral boundaries of the rectus sheath which contains the rectus abdominis muscle.
What is the clinical significance of the linea alba in surgery?
Provides a relatively avascular plane to make a midline incision thus minimising blood loss.
However, poor blood supply to the linea alba can mean that it does not heal well.
How many regions can the abdomen be divided into during clinical exams?
9 (2 vertical and 2 horizontal lines)
What are the vertical lines that divide the abdomen?
The left and right mid clavicular lines
What are the horizontal lines that divide the abdomen?
The subcostal and transtubercular lines
Describe the subcostal line
More superior and joins the most inferior points of the costal margins
Describe the transtubercular line
Passes through the tubercles of the iliac crest (approximately 5cm posterior to the ASIS).
At what vertebral level does the subcostal line lie?
L3
At what vertebral level does the transtubercular line lie?
L5
What are the 9 regions of the abdomen?
Right Hypochondrium Epigastrium Left Hypochondrium Right Lumbar Umbilical Left Lumbar Right Iliac Hypogastrium Left Iliac
Where is the transpyloric plane?
Halfway between the manubrium and the pubis
Lies at L1
What does the transpyloric plane pass through?
Pylorus of stomach and 1st part of duodenum
Fundus of gallbladder
Neck of pancreas
Origin of SMA
Origin of hepatic portal vein
Root of transverse mesocolon
Hila of kidneys
How is abdomen palpation performed?
- Light palpation
- Deep palpation
- Organ-specific palpation
How is light palpation performed?
Placing the right hand on the abdominal wall and gently flexing the metacarpophalageal joints (knuckles) as shown in the diagram below. You should palpate ALL nine regions ensuring that none are omitted.
Useful in determining if there are any regions of tenderness
What is guarding?
Contraction of the abdominal muscles to protect the underlying viscera during palpation, particularly if there is pain.
What is deep palpation?
Pressing harder with the right hand or using both hands together as shown below.
A solid mass may be felt in left lumbar region during deep palpation. What is this likely to be?
Faeces in descending colon
Where is McBurney’s point?
Located 1/3 of the way from the ASIS to the umbilicus
What would tenderness in at McBurney’s point during palpation indicate?
This is the location of the base of the appendix therefore pain here indicates appendicitis.
When is organ specific palpation performed?
Performed to check for any enlargement. This includes palpation of the liver, spleen, kidneys. These organs are not usually palpable in healthy individuals unless very thin. This is because they are protected by the thoracic cage.
Describe the relation of the spleen to the thoracic wall
The spleen lies deep to ribs 9-11 and is well protected by the thoracic wall. Although mobile, the spleen does not move below the costal margin even during deep inspiration therefore it is not normally palpable.
Describe the relation of the liver to the thoracic wall
The liver normally lies deep to ribs 7-11 on the right side and crosses the midline where it tapers towards the left nipple. The position of the liver is not constant, it moves up and down with respiration. During deep inspiration the inferior border of the liver moves below the costal margin facilitating palpation.
Describe the relation of the kidneys to the thoracic wall
The superior parts of the kidneys lie deep to ribs 11-12, however, the inferior parts of the kidney are not protected by the thoracic cage. Like the liver, the kidneys are mobile and move 2-3cm in the vertical direction during respiration.
What is hepatomegaly? What can it be caused by?
Enlarged liver
Infections, cancer and alcoholic liver disease
Where does the liver enlarge towards?
Towards the right iliac fossa
The border of which may be palpable in very thin individuals in the absence of hepatomegaly
How should liver palpation occur?
The liver enlarges towards the right iliac fossa therefore this is where palpation should begin, moving up towards the costal margin. The position of the liver changes with respiration (as shown below) therefore, palpation should be synchronised with respiration
What is Murphy’s sign and what does it indicate?
This is pain elicited as the patient breathes in during liver palpation. It occurs when an inflamed gallbladder passes the examiner’s fingers.
Where does the liver enlarge towards?
Right iliac fossa, crossing the abdomen diagonally
The spleen must increase in size 3 fold before it is palpable! This means a palpable spleen always indicates splenomegaly.
What prevents the spleen enlarging inferiorly to the left iliac fossa?
The phrenicocolic ligament – part of the peritoneum between the diaphragm and hepatic flexure of the colon. It passes below the spleen and helps to support it.
This isn’t present on the right side
How are the kidneys palpated?
Using a bimanual technique. The left hand is placed on the patient’s back below the lower ribs and the right hand is placed on the anterior abdominal wall in the lumbar regions.
How can the abdominal aorta be palpated?
Particularly in thin individuals. A normal aortic pulse should push the examiners fingers upwards. If the fingers are pushed laterally this is described as an expansile aortic pulse and may indicate an abdominal aortic aneurysm.
What is an abdominal aortic aneurysm (AAA)?
Balloon-like swelling of the aortic wall
Why should an AAA be monitored?
This weakens the aortic wall and could potentially rupture causing rapid haemorrhaging. A ruptured aortic aneurysm has a mortality rate of almost 90%.
What are the abdominal organs (viscera) sensitive/insensitive to?
Insensitive to touch, temperature and cutting. Pain is instead elicited by stretching or chemical irritation
Is pain from the viscera well or poorly localised?
Poorly localised as it is referred to the dermatomes corresponding the spinal nerves that provide the sensory fibres.
The pain is normally referred to the middle of the corresponding dermatome
Where is pain from the foregut usually referred to?
Epigastric region
Where is pain from the midgut usually referred to?
Umbilical region
Where is pain from the hindgut usually referred to?
Pubic region
What visceral afferent (sensory) fibres is the stomach supplied by?
Where is pain from the stomach referred to?
Fibres from T7-T8 spinal nerves.
Pain is the stomach is therefore interpreted by the brain as coming from the dermatomes supplied by T7-T8.
Why does pain from appeciitis move from the umbilical region to the right iliac fossa?
Pain is initially dull and poorly localised to the umbilical region because the appendix is a midgut derivative supplied by afferent fibres from T10 level of spinal cord therefore the brain interprets the pain as coming from the T10 dermatome.
As the inflammation and swelling worsen, the parietal peritoneum becomes irritated. The parietal peritoneum is part of the body wall and is supplied by somatic sensory fibres therefore the pain becomes sharp and very well localised in the right iliac fossa
