Anatomy Flashcards
What is x-ray absorption dependant on?
i. Thickness of tissue
ii. Density of tissue (mass per unit volume)
iii. Atomic number of tissue (to the 4th power) = STRONGEST INFLUENCE: H = 1, C = 6, O = 8, Ca = 20
What does it mean if something is more black on an x-ray?
If something is more black it is more lucent or less opaque (backer)
What is the order of lucency of components of the body?
Air -> fat -> soft tissues, muscle, liver, fluid -> bone
How do we improve the natural differences in x-ray absorption?
Contrast medium
Barium meal
Barium enema
Endoscopic retrograde cholangiopancreatography (ERCP)
Percutaneous transhepatic cholangiograph
Inject radio-opaque material into vessels
What is barium meal?
patient ingests barium (atomic number 56) -> moves through the GIT and allows visualization of the GIT i. Visualize esophagus and stomach almost instantly 1. Commonly endoscopy/gastroscopy is used instead ii. To visualize small bowel drink higher volume and take X-rays over a period of hours (1 hour) 1. Commonly used as small bowel hard to reach with endoscopy
What is a barium enema?
contrast into rectal tube under gravity allows visualization of the large intestine (must clean colon beforehand) i. NB. colonoscopy largely replaced this examination
What is the Endoscopic retrograde cholangiopancreatography (ERCP)
canulate the ampulla of the pancreas and introduce contrast which runs into the bile duct or pancreatic duct
What is Percutaneous transhepatic cholangiography?
Inject thin needle with contrast into the liver allowing visualization of the bile ducts
How do we visualise vessels under x-ray?
Intravscular contrast medium injected either intravenously or intra-arterialy.
Commonly organic salts containing iodine
The contrast medium then distributes through the blood vessels (sometimes extravascular as well). This is then visualised by taking a series of x-rays in quick succession
What is a celiac angiogram?
- Catheter -> select branch of aorta -> 50-20ml of contrast injected and images rapidly taken 2. See it moving through small arteries, capillaries then veins
What is indirect protography?
Catheter-> splenic artery -> 20 seconds -> dense blush -> contrast is opacifying the blood through the splenic vein and as a result of that the portal vein can be visualized
What is an intravenous contrast with biliary excretion?
Molecule transported by hepatocytes complexed to contrast agent which contains iodine -> visualization of the bile ducts
How does a CT scan work?
Ring of X-ray detectors with a moving X-ray tube and the patient is also moving
10-15 seconds to do the entire chest and abdomen (one breath hold)
What is the unit of measurement in a CT scan. What is an area referred to as in a CT scan?
Housenfield unit (greyscale) Voxel - pixel with depth
What is radio-isotope imaging?
Radioisotopes (most common is Tc-99m, good energy short half-life) i. Attach to particular molecules (targets certain tissues) -> introduce to body (usually intravenous) ii. Emit gamma rays -> recorded by “gamma camera”
What is radioisotope biliary imaging?
Radioisotope attached to molecule which behaves like bilirubin ii. Taken up by hepatocytes and excreted iii. Isotopes show up as black (hot areas)
What are the advantages and disadvantages of radioisotope imaging?
Advantage = functional, physiological Downside = poor anatomical resolution
What imaging techniques use ionizing radiation?
Why should it be avoided?
X-ray
CT
PET
Ionizing radiation can be harmful
How does ultrasound worK
Produces thin sectional imaging using echoes returned from tissue interfaces
What is dopler ultrasound?
Doppler effect describes a perceived change in frequency of waves when there is relative movement between source of the wave and observer of the wave
ii. In this case source of sound is the RBC; generate weak echoes but it is strong enough
iii. When ultrasound probe picks up echoes it measure frequency; different to frequency which has gone out -> Doppler shift -> work out which way the blood is flowing
iv. Put a measuring cursor on the screen which feeds into a Doppler frequency equation
What can be measured with a Doppler ultrasound?
i. Allows you to measure speed of blood flow as well as direction ii. Is their blood flow? What direction is it? How fast is it?
How does MRI work?
i. Body is made up of H -> spinning with positive charge -> small magnetic field
ii. In the body there are many spinning protons which magnetic moments -> line up when placed in strong magnetic field (MRI) -> net orientation in line with the magnetic field
iii. Images which are constructed so that you rely on how the magnetization reverts to normal iv. Two parameters in the formulae to describe how magnetization get back to where it was - T1, T2 constants 1. Weight sequencing so that you make use of T1 or T2 2. T1 = (stationary) fluid are black on T1 3. T2 = (stationary) fluid are white on T2
What are the dangers of MRI?
Need to avoid anything metalic
- Cant be used if someone has a pacemaker etc
What percentage of the liver’s blood supply comes from the portal vein and hepatic artery?
What relative oxygen contribution do they make?
i. Portal vein = 75% ii. Hepatic artery = 25%
Both contribute about 50% of the oxygenation
Where is the bifurcation of the aorta?
L5
What are the layers of the anterior abdominal wall?
Skin Superficial fascia 3 flat layers of muscle Deep fascia (transversalis fascia) Extra peritoneal Peritoneum
Where is rectis abdominis found?
Either side of the midline. Vertically
What is the visceral and parietal peritoneum?
The peritoneum lines the walls of the cavity where it is called the parietal peritoneum - it reflects off the abdominal wall at various points to surround visceral structures
- Visceral (where it surrounds viscera) vs parietal
What is the pubic tubercle?
The pubic tubercle is the bump of bone at the lateral end of the pubic crest
What replaces the 3 flat muscles of the anterior wall medially?
Aponeurosis
What is an aponeurosis?
It is a flat, broad tendon. They have a shiny, whitish-silvery color, arehistologically similar totendons, and are very sparingly supplied withblood vesselsandnerves,
What happens to the two aponeurotic extensions in the midline?
They interdigitate in the midline, knitting together to form a vertical raphé - this is called the linear alba (meaning white line)
What is the ASIS?
Anterior superior iliac spine
What type of muscle is the external oblique?
It is a front pockets muscle (downwards and forwards)
Where does external oblique end superiorly?
It overlaps onto the front of the thoracic cage, it comes up to and edge to edge with pec major and serratus anterior
Where does external oblique attach anteriorly?
Attaches tot he anterior half of the iliac crest, as far as ASIS.
It then jumps to the pubic tubercle and pubic crest
What is the free edge of external oblique, why does it exist?
The jump of external oblique from the ASIS to the pubic tubercle and crest creates the free inferior edge.
The free inferior margin is thickened and turns under itself forming what is called the inguinal ligament.
What happens after the externa; oblique attaches inferiorly?
The free inferior edge attaches to the pubic tubercle and then there is a triangular opening in the aponeurotic part of external oblique before the final attachment to the pubic crest
What type of muscle is internal oblique?
It is a back pockets muscle (directed downwards and backwards)
Where does internal oblique attach superiorly?
It attaches directly onto the costal margin
Where does the internal oblique attach inferiorly?
The Internal oblique attaches to the iliac crest as far as the ASIS.
The lowermost fibres of the internal oblique take origin from the lateral 2/3rds of the inguinal ligament.
Where are the fibres of the internal oblique that attach to the inguinal ligament heading?
These fibres do not head to the linear alba to meet with the lowermost fibres of internal oblique from the other side, rather they are arching Upwards Over and Down to insert into the pubic crest on their own.
What is the arrangement of the fibres in the transversus abdominus?
The muscle has horizontal/transversely arranged fibres.
Why are the muscles of the transversus abdominus arranged transversely?
The reason for this arrangement is for strength, the strongest anterior wall upon contraction will come from having 3 different fibre directions
What functions are controlled (in part at least) by the contraction of the abdominal muscles?
Defacation, urination, childbirth, coughing
Where transversus abdominus insert superiorly?
This muscle underlaps the costal margin and is in the same plane as the diaphragm.
Where do the transversus abdominus and internal oblique end posteriorly?
They extend around as far as the thorico-lumbar fascia
Where do the lowermost fibres of the transversus abdominus arise from?
The lowermost fibres come off the iliac crest and then continue to arise from the lateral part of the inguinal ligament (lateral 1/3)
How are the muscles of the transversus abdominus arranged inferiorly?
They do not go to the linea alba, rahter they arch upwards over and downwards to insert into the pubic crest (like internal oblique)
Do transversus abdominus and internal oblique insert into the pubic crest together?
Transversus abdominus and internal oblique are intimately related to one another so they insert into the pubic crest via a conjoined tendon
Where does the rectus abdominus arise inferiorly?
The pubic crest
What happens to the fibres of rectus abdominus as it ascends?
They diverge
Where does rectus abdominusn attach superiorly?
It crosess the costal margin and attaches to the the costal margins of 5,6,7 (it is basically edge to edge with pec major)
What is the issue with long muscles?
They are generally not very powerful
Why does rectus abdominus have a series of tendinous intersections in its verticle ascent?
It creates muscle fibres which are shorter and thus stronger
Where are in intersections of rectus abdominus?
Umbilicus
xiphisternum
One in between
How do each of the aponeurosis cross the midline?
The three aponeurosis then create an envelope, fascia or an aponeurotic envelope or sheath around rectus abdominus as they head to the midline (linear alba)
Which side of the rectus abdominus do each of the aponeurosis cross the midlinein the upper rectus sheath?
The external oblique aponeurosis goes in front forming the front of the rectus sheath, the transversus goes behind and the internal splits with half going in front and half behind.
Where does the conformation of the aponeurotic crossover change?
About an inch below the umbilicus
In the lower recuts sheath how do the aponeurosis cross the midline?
All of the aponeurosis go in front of the rectus abdominus forming the anterior rectus sheath. There is no posterior rectus sheath.
What is the line of demarcation where the posterior rectus sheath cuts out?
It is an arched demarcation called the ARCUATE LINE
Where is the neuromuscular plane located in the anterior abdominal wall?
Between the internal and deep layers (between teh internal oblique and transversus abdominus)
Where is the umbillicus?
T10
What is the level of the groin?
L1
What are the blood vessels of the abdomeninal wall?
The main arterial supply is from a superior and inferior epigastric from above and below.
These vessels run in the rectus sheath.
They run deep to rectus abdominus in the posterior part of the rectus sheath
Where does the superior epigastric come from?
It is a branch of the internal throacic
Where does the inferior epigastric come from?
It is a branch of the external iliac artery
Why is drainage of the anterior abdominal wall important in portal hypertesnsion?
The site of overlap (between portal and systemic venous drainage) become importnant when a patient has portal hypertension.
The anterior abdominal wall is one of the sites of porto-systemic anastomoses
What is the venous drainage of the anterior abdominal wall?
The superficial and deep veins accompany the arteries
What is the lacuna ligament?
The lacuna ligament is the crescentic extension onto the pectineal bone
What is the pectineal ligament?
The linear extension from the pectineal ligament is called the Pectineal line
Where do the testis develop?
The testis develop in the extra peritoneal fat on the posterior abdominal wall (quite high up)
What do the testis need to get through to get into the scrotum?
Transversalis fascia
Transversus abdominus
Internal oblique
External oblique
Where is the cremaster muscle, what does it do?
○ These are the fibres which produce testicular retraction when it is cold
○ The muscle fibres particularly come from internal oblique
○ The fibres are arranged in whirls around the structure.
How do the testis get through the fascia transversalis?
- Testis create a deficiency in fascia transversalis half way between the ASIS and the pubic tubercle and a fingers breadth above the inguinal ligament
The hole created by the testis is called the Deep inguinal ring
How do the testis get through Transversus abdominus and Internal oblique?
- The lower most fibres arise from the lateral part of the inguinal ligament and arch upward over and downward and insert into the pubic crest
Thus if the testis turn medially and in the direction of the whole in external oblique they can travel through the arch formed by the arching fibres of transversus abdominus and Internal oblique which travel down to from the conjoined tendon and insert into the pubic crest.
This is called the inguinal canal, the entry point is the deep/internal inguinal ring
How do the testis get through external oblique?
- The inguinal ligament attaches to the pubic tubercle and then there is a triangular gap before continuing on in its attachment to the pubic crest
- This is called the external or superficial inguinal ring
Where does the nerve supply and vasculature of testis come from?
As the testis descends they take with them their nerve supply, veins, arteries and lymphatic as well the vas deferens (its duct) into the scrotum. These are the structures which comprise the spermatic cord.
What happens as the testis cross each layer of the anterior abdominal wall?
As the spermatic cord travels through each of the layers of the anterior abdominal wall it gets a layer of covering (i.e. by the end they have 3 layers and are very well protected)
What is the layer of covering the testis get from the deep ring?
Internal spermatic fascia
As the testis turn medially and pass the arching fibres of transversus abdominus and Internal oblique another layer is added this is called the….
Cremasteric fascia it is called this because there are some muscle fibres associated with it (crematsa)
What is the layer of covering the testis get from the external ring?
External spermatic fascia
It is only at this point that it is technically called the spermatic cord
What is an abdominal hernia, how does it occur?
When intra-anterior abdominal wall contracts and intra-abdominal pressure rises and everything gets to crowed, there is a propensity for the contents to find a way out (I.e. a point of weakness).
The abnormal protrusion of abdominal contents through the abdominal wall is called an abdominal hernia.
What are the causes of an abdominal hernia?
congenital or postoperative
eg If the layers of the abdominal wall are not stitched up properly after an operation a hernia can occur
What is an inguinal hernia?
The abnormal protrusion of the abdominal contents into the inguinal canal is called an inguinal hernia.
The contents could be pushed back into the abdominal region and the internal/deep ring could be sown up to prevent herniation in the future.
This can be omentum (commonly) or loops of bowel
What is an indirect inguinal herniae?
It is called an indirect hernia because it has to go through quite an indirect route in order to through to the scrotum. It is possible to get bilateral direct inguinal hernia where the contents of the abdomen are pushing through the weakest part of the anterior abdominal wall. The weakest part of the anterior wall in the inguinal region relates to the posterior wall of the inguinal canal.
What is a direct inguinal hernia?
A direct inguinal hernia , it has nothing to do with the deep ring. Rather it is just bulging out through the region of the inguinal canal through the posterior wall. (it does not enter the scrotum)
Where is an inguinal hernia likely to occur?
Between the inferior epigastric artery and the rectus abdominus is the weakest part of the anterior abdominal wall - it is quite easy for the inguinal contents to bulge through at this point.
It is called the inguinal triangle
What is a sliding hiatus hernia?
Stomach protrudes out of Abdominal Cavity. Generally from Reflux.
What us a rolling/paraoesophageal hernia?
Volvus hernia (twist of the stomach)
What is Mekel’s diverticulum?
Small bulge (outpouching) in SI at birth
What are some reasons why the bowel may be narrowed?
Adhesions (most common)
Volvus
Abdominal wall hernia
What is a ileo-anal pouch operation?
a surgically constructed internal reservoir; usually situated near where the rectum would normally be. It is formed by folding loops of small intestine (the ileum) back on themselves and stitching or stapling them together. The internal walls are then removed thus forming a reservoir. The reservoir is then stitched or stapled into the perineum where the rectum was. The procedure retains or restores functionality of the anus with stools passed under voluntary control of the patient.
What is an ileostomy?
- LI is not functioning.
* Drain waste externally through portion of ileum
What is achalasia?
A failure of smooth muscle fibers to relax, which can cause a sphincter to remain closed and fail to open when needed. Without a modifier, “achalasia” usually refers to achalasia of the esophagus, which is also called esophageal achalasia,
What does achalasia lead to?
Barret’s oesophagus
What are some of the sequale of duodenal ulcers?
Internal bleeding, Infection, scar tissue
They often require surgery
Why does one need to be careful when performing surgery on the gall bladder?
- A lot of variation around anatomy of gallbladder
* Ie cystic duct can be long/short or join right hepatic bile duct.
What is a laproscopoy and a laparotomy?
Laprascopy: -> AKA minimally invasive surgery AKA keyhole surgery
• Surgery made with small incisions (1cm) into abdomen.
Laprascopy: ->AKA minimally invasive surgery AKA keyhole surgery
• Surgery made with small incisions (1cm) into abdomen.
What forms the paravertibral gutters?
It is the projection of the 5 lumbar vertebrae
What floors the paravertibral gutters?
Powerful longitudinal muscles
What is psoas major?
It is a pair of muscles directly adjacent to the vertebral column
What overlies psoas major in 2/3rds of cases?
psoas minor
What muscles are lateral to the psoas major?
Quadrartus lumborum is superolateral
Iliacus is inferolateral
Locate psoas major
Lies in the paravertebral gutter, adjacent to the lumbar vertebral body
It is directly adjacent to the lumbar vertebral bodies, overlying the lumbar transverse processes
What is the origin of psoas?
Psoas has one continuous origin, from the lower boarder of T12 to the upper boarder of L5
What is the role of psoas?
It is an important flexor of the vertebral column, it is important in maintaining an erect spine
When it weakens one often gets an increased lumbar lordosis
What is psoas attached to?
Because it is a strong muscle and needs to be well anchored it is attached at both the lumbar vertebral bodies but also the disk in-between
i.e. it attaches from T12-L5 to the vertebral disks and to the medial ends of the transverse process
What happens in the inferior region of psoas?
The fibres converge (after L5), pass beneath the inguinal ligament and insert into the lesser trochantor of the femur
Where is the lumbar plexus located?
The Lumbar plexus is within psoas, the lumbar vessels are behind psoas and the sympathetic trunk is in front of psoas (as well as psoas minor if it is present)
Where are the lumbar vessels located?
The Lumbar plexus is within psoas, the lumbar vessels are behind psoas and the sympathetic trunk is in front of psoas (as well as psoas minor if it is present)
Where is the sympatheitc trunk located?
The Lumbar plexus is within psoas, the lumbar vessels are behind psoas and the sympathetic trunk is in front of psoas (as well as psoas minor if it is present)
What is the character of psoas minor?
Long slender tendon and a short slim belly - which means it is phylogenetically degenerating (i.e. disappearing from the species)
It blends with the periosteum of the pelvis and peters out (it does not do very much)
Where does quadratus lumborum attach?
Attaches above the 12th rib
It attaches to the tips of the transverse processes and to the posterior half of the iliac crest below
What is the role of quadratus lumborum?
It is a stabiliser of the 12th rib and a lateral flexo
Where is illiacus located?
Below quadratus lumborum
What shape is iliacus?
It is an inverted triangle shape
Where does the iliacus arise attach inferiorly?
The iliac bone has a smooth fossa on its internal surface called the iliac fossa.
This is where the iliacus arises
Where does the iliacus insert
It is edge to edge with psoas and the fibres converge to pass beneath the inguinal ligament from which it heads to the lesser trochanter
What is the common insertion of the iliacus and psoas called?
Called the conjoined tendon - the iliopsoas
What encloses each of the muscles?
Fascia
How many layers does the thoracolumbar fascia have?
3 (trilaminar structure)
To be precise it is only really 3 layers in the lumbar region
What are the 3 layers oif the thoracolumnar fascia?
One layer attached to the tip of the spinous process, this is the thoracolumbar posterior layer
A second layer is attached to the tip of the lumbar transverse process, this is the middle layer
There is a 3rd layer which is attached to the anterior region of the transverse process, this is anterior layer
Where do the 3 layers of thoracolumbar fascia fuse?
All three of the layers fuse laterally, along the line of the 12th rib
Where is quadratus lumborum relative tot eh thoracolumbar fascia?
Quadratus lumborum is enclosed in the anterior compartment of the thoracolumbar fascia
What is contained in the anterior compartment of the thoracolumbar fascia?
Posterior layer which contains erector spinae (this posterior lamina which overlies erector spinae will extend for the whole extent of erector spinae from cervical region to sacrum)
Where do the muscles of the anterior abdominal wall insert posteriorly?
Transversus abdominus and Internal oblique connect to the lateral edge of the thoracolumbar fascia
Posterior layer which contains erector spinae (this posterior lamina which overlies erector spinae will extend for the whole extend to erector spinae from cervical region to sacrum)
What is a presentation of TB that can affect the vertebrae?
tuberculous osteomyelitis
What can happen if someone has tuberculous osteomyelitis in the lumbar vertebrae?
If it is in the lumbar vertebrae it can break through the bony cortex and erupt into psoas
The fascias are really dense structures and as such the caseous material associated with the TB rather than erupting through the fascia would be channelled down in the psoas fascia and present as a lump in the groin - i.e. it tracks down with psoas beneath the inguinal ligament to the insertion in the lesser trochantor
What is the name given to structures completely surrounded by peritoneum?
Structures completely surrounded by peritoneum and these are called intraperitoneal
What is the name of structures which have their backs to the abdominal wall?
Structures which have their backs to the posterior abdominal wall and in which the parietal peritoneum must leave the posterior peritoneal wall in order to reflect over the front of them are called retroperitoneal
Where are the kidneys located?
Lateral to the vertebral column in the paravertebral gutters on quadratus lumborum
They are classically described as extending from T12 - L3, anterior to the 12th rib
The right sits slightly lower than the left
This is due to the liver which sits up on the right and pushes the right kidney down a little
Do the kidneys move during respiration?
Yes - thus their exact static position is not so important
What are the two appoaches that a surgeon could take when operating on the kidneys?
Can take the anterior approach and cut through the structures of the anterior abdominal wall (i.e. through all the muscle sheaths and fascia etc. or through the linea alba - in both cases the surgeon would need to make their way around the structures of the abdomen
By going in posteriorly one can avoid going through peritoneum altogether and would only be required to go through the relatively simpler structures of the posterior abdominal wall
What are the drawbacks of taking the anterior approach to the kidneys in surgery?
Not ideal as entering the peritoneal cavity should be avoided if possible, indeed just handling the structures sets up a fibrinous inflammatory process and potentially all sorts of adhesions
What are the costs/benefits of taking a posterior approach to the kidneys in surgery?
In some cases this requires removal of the 12th rib and if attempting to create a really open surgical field a surgeon may opt to take out the 11th as well
At this point there is really great access to the kidney, indeed it can be accessed from both the lumbar or the lateral side. (i.e. through the muscles of the posterior abdominal wall - through psoas or adjacent to it) or by removing the ribs you can go in laterally.
The patient can be positioned for this approach
What are the dimensions of the kidney?
10cm long, 5cm wide and 2.5cm thick
What is on top of the kidneys?
Adrenal gland/suprarenal gland associated with the superior aspect of each
What does the left suprarenal gland look like?
Crescent shaped structure
This is associated with the upper pole - it is superomedial - it wraps down onto the medial surface
What does the right suprarenal gland look like?
Pyramid/party hat :)
This sits at the apex of the kidney
What are the features of a solid viscera (and by extension the kidney)?
They are composed of clusters of secretory cells
(Divided into lobes/nodules/cortex/medulla)
Enveloped by a capsule
(fibrous capsule)
Kidney is typically enclosed by fat (quite a lot)
(It s called peri-renal fat and this is enclosed by renal fascia)
How are secretory cells arranged in the kidney?
Secretory cells are arranged into outer cortex and inner medulla
The outer cortex is a continuous band of pale tissue which completely surrounds the inner medulla
Inner darker medulla is discontinuous darker triangles or pyramids (These are often called the medullary or renal pyramids. Their base is towards the surface of the kidney and their apex points towards the hilum)
What direction to the hila of the kidneys face?
Because the kidneys are effectively behind the paravertebral column the hila of the kidney face antero-medially
What is the order of vessels from front to back?
VAD
Vein, artery duct
Renal vein, renal artery and ureter
Nerves and lymphatics are also present but are scattered and not part of the front to back arrangement
Where are the Vein artery and ureteric pelvis embedded?
In fat, in a space within the kidnye which is continuous with the hilum. It is called the renal sinus
How many renal arteries are there and where does it branch from?
There is a single renal artery which supplies each kidney
It is a lateral branch off the abdominal aorta
What is the orientation of the renal artery?
It is horizontal (i.e. it comes straight off the sides) and enters the hilum of each kidney
What happens to the renal artery once it enters the hilum of the kidney?
Once it enters the hilum of the kidney it divides into 5 segmental arteries
What is commonly seen with the blood supply of vital organs (and perhaps the organ itself)?
They are split into discrete functional segments, that way if something goes wrong in some of the segments the organ can continue to function
What organs are split into discrete functional segments?
Liver
Lungs
Kidney
Where does kidney development begin and what happens during growth?
When the kidney develops it starts off lower on the abdominal wall and then differential growth rates result in change in position relative to the vertebral column and posterior abdominal wall structures
What happens to the blood supply of the kidney during development?
As it changes position it changes blood supply - it loses its lower blood supply and then gains a new one.
Normally when it gets up to its final position it just has a single pair of renal arteries coming off either side of the descending aorta
What is an anatomical variation that is observed as a result of the changing blood supply to the kidney throughout development
In some cases can see an accessory renal artery (or more than one) which represents a persistence of one from lower down (up to 25% of individuals)
These can enter the hilum as an extra vessel or in some cases pierce the external surface separately
Need to isolate these in surgery (i.e. need to tie off extra arteries)
Where does the right renal vein drain?
Directly into the IVC
Where does the left renal vein drain?
Crosses the front of the abdominal aorta to enter the left hand side of the IVC
Where does the right renal artery cross with respect to the IVC?
Why?
It passes behind the IVC.
If it passed in front it would be compressed by the IVC with the lumbo-vertibral column behind
What is the ureteric pelvis?
It is the dilated part of the upper ureter
What is the position of ureteric pelvis in the hilum?
It is the most posterior structure
What does the ureteric pelvis receive?
It receives four major calyces
What do the major calyces collect?
2/3 minor calyces
What do the minor calyces collect?
The minor calyces receive the apex of the downward pointing medullary triangle or pyramid
Where are the ureters found?
In the retroperitoneal space, directly assocaited with the peritoneal wall
What is the function of the ureters and how long are they?
These are muscular tubes which transport urine from the kidney to the bladder
They are 25-30cm long
They descend on the posterior abdominal wall structure
What descends along psoas?
Ureters (overlies) Lumbar plexus (within) Lumbar vessels (behind) Sympathetic trunk (on psoas)
How do the ureters descend on psoas?
The descent of the ureter is vertical, whilst Psoas is oblique the path of the ureter corresponds to the tips of the lumbar transverse processes
What happens after the ureters cross psoas?
The ureters then tip over the pelvic rim into the pelvis.
They run along the side wall of the pelvis and then turn and enter into the bladder.
Where does the blood supply to the ureters come from?
Ureters follow a relatively long course and as such take blood supply from whatever they are passing (i.e. any adjacent artery)
All muscular tubes have sites of narrowing where are they usually located?
Always at the beginning and end and sometimes associated with external structures
What is the first site of narrowing in the ureter, what might get lodged here?
The first site of narrowing in the ureter is at the beginning (From the ureteric pelvis to the start of the ureter)
- A big stone will lodge here
How does the ureter pass through the ladder wall?
The ureter passes obliquely through the wall of the bladder.
Why does the ureter pass obliquely through the bladder wall?
When the bladder expels urine during urination the wall of the bladder contracts, the pressure inside the bladder exceeds that outside and hence there is urine flow.
However when the bladder contracts pressure also exceeds ureteric pressure, thus one might expect to see regurgitation
The oblique course of the ureter prevents regurgitation.
Because the ureter burrows through the muscle of the bladder wall at an angle a contraction will cause the terminal region of the ureter to close off.
This is a physiological spincter
What are the second and third sites of narrowing in the ureter?
2nd - the ureter gets kinked as it tips of over the pevlic rim (this is another site where kidney stones can lodge)
3rd At the end of the ureter as it enters into the bladder
Where doe the oesophagus begin?
How long is it?
25 cm
Begins at the pharynx
Specifically at the level of cricoid cartilage at the level of C6
What is the pathway of the oesophagus?
Extends through the neck (begins at the pharynx) thorax and abdomen (only a small part kniown as the abdominal oesophagus which enters the stomach)
How long is the abdominal oesophagus?
About 1.25 cm long
Where doe the abdominal oesophagus enter the stomach?
Right hand side of the stomach
How does the oesophagus descend?
It descends in the midline and it intimately connected tot he trachea (behind it)
In thorax is passed through the posterior mediastinum
It corsses the muscular part of the diaphragm at the level of T10
What change happens at the oesophago-gastric junction?
here is a change from the stratified squamous epithelium lining the oesophagus to the gastric mucosa lining the stomach.
What is the Z line?
This is the line which demarcates the separation between the oesophagus and the stomach
What is the narrowing of the cervical oesophagus?
Upper oesophageal sphincter.
This is a true sphincter
What supplies the cervical oesophagus?
Inferior thyroid artery
Where does the cervical oesophagus drain?
Brachiocephalic vein (systemic)
Where does the cervical oesophagus lymph drain?
Deep cervical nodes
Where is the narrowing of the thoracic oesophagus?
The aortic arch and left main bronchus, arching across to the left hand side extrinsically compress the oesophagus and produce a narrowing.
o These compressions are pretty close together and are sometimes considered to be one compression others will talk about them separately
What supplies the thoracic oesophagus?
Supplied by the oesophageal branches from the aorta
Where does the thoracic oesophagus drain?
- Drains into the azygous (Systemic)
Where does the thoracic oesophagus lymph drain?
Lymph drains into the mediastinal nodes
Where is the narrowing of the abdominal oesophagus?
e narrowing in this region is produced by the diaphragmatic orifice
o The sling of muscular fibres around the distal part of the oesophagus
What supplies the abdominal oesophagus?
Supplied by the left gastric from the aorta
Where does the thoracic abdominal drain?
- Drains into the left gastric vein
o All the other structures drain into the systemic drainage but this drains into the portal system
Where does the thoracic abdominal lymph drain?
Lymph drains into the pre-aortic nodes
What is a hiatus hernia?
the herniation of part of the stomach up through the oesophageal hiatus and diaphragm and into the posterior mediastinum.
What are most hiatus hernias?
- 95% are sliding hiatal hernias.
The whole system is pulled up.
Stomach is squashed by the oesophageal hiatus
What are the less common forms of hiatus hernias?
- 5% are paraoesophageal hernias.
This is where the top part of the stomach slides up through the oesophageal hiatus next to the oesophagus.
The oesophagus is still going through the hiatus but is squashed by a little bit of the stomach which is pushed up as well
Where is the stomach located?
The upper left quadrant of the abdomen
What is the shape of the stomach?
It is roughly J shaped but this changes with body position
What are the two openings of the stomach?
Proximal
Known as the CARDIAC ORIFICE.
It is not at the top of the stomach but rather on the right hand side
Distal
The continuation into the duodenum.
Known as the PYLORIC ORIFICE
What are the curvatures of the stomach?
The greater curvature on the underside (left hand side)
The lesser curvature, this is on the ‘top’ and is a smaller and tighter curve
What is the fundas of the stomach, where is it?
This is the dome shaped region that projects above the cardiac orifice.
It sits directly below the left dome of the diaphragm
What is in the fundas, what is observed radiologically?
The stomach is filled with both liquid and gas and the air bubble within usually fills the fundus
Thus on a radiological film under the left dome of the diaphragm there will be a gas bubble observable (gastric gas bubble) which outlines the fundus underneath which will be an gas liquid interface ]
What is the body of the stomach, where is it?
o This extends from the cardiac orifice to the angular notch (or incisura)
Along the lesser curvature is a clear notch called the angular notch (incisura), this defines the end of the bod
Besides the body and funds what is the other section of the stomach?
The pyloric antrumn
What is the pyloric antrum?
It is a narrowing towards the pyloric canal
What is the pyloric canal?
It is the last and most tubular part of the stomach. It has a thick muscular wall called the pyloric sphincter
What is the pyloric sphincter?
It is the region of the stomach that controls passage into the duodenum which is only capable of processing small amounts of chyme at a time.
How is the stomach attached to the liver?
The lesser curvature is tethered to the liver superiorly by a double folded peritoneum called the lesser omentum
Where is the greater omentum attached to the stomach?
It attaches the greater curvature of the stomach to
Where does the greater omentum end superiorly?
It ends in a gasto-splenic ligament which is a double folded peritoneum connecting the greater curvature to the spleen
What are the prominent longitudinal mucosal folds of the stomach called?
Rugae
What is the pattern of rugae in the stomach?
They increase in prominence closer to the pylorus
Where do the arteries to the stomach run?
Along both the lesser and greater curvature, there are anastomoses on both
What are the names of the arteries of the stomach?
- Right and left gastric artery
o These run along the lesser curvature - Right and left gastroepiploic arteries
Running along the greater curvature
Where do the veins of the stomach drain into?
The portal circulation
What is the duodenum?
It is the tubular region distal to the stomach.
It is the first part of the small intestine
It is 10 inches long.
How many parts of the duodenum are their and what shape do they form?
It is in 4 parts and forms a C shaped loop around the head of the pancreas
What quadrant is the duodenum in?
- The duodenum does not neatly fit into a quadrant, rather it is overlying the vertebral column
It is positioned centrally and can be related to psoas muscles
Is the duodenum intra or retro peritoneal?
All but he first inch is retroperitoneal
What is the primary function of the duodenum?
What structural features are present to facilitate this?
The primary function of the duodenum is absorption of digestive products
o Thus the surface area is increased by surface folds and microscopic villi
o The pyloric sphincter controls entry and limits it to small parts at any one time
What is the first part of the duodenum?
It is the duodenal cap
How long is the duodenal cap?
What is the heading of the duodenal cap?
It is heading upwards and back towards the posterior abdominal wall to become retroperitoneal
It is 2 inches long (1 inch is intraperitoneal and 1 inch is retroperitoneal)
what is a common pathology associated with the duodenal cap?
Most peptic ulcers occur here or in the stomach. This results from an imbalance in acid secretion and mucosal defences
Where does the duodenum come to lie?
It comes to lie on the right psoas just medial to the right kidney
How long is the second part of the duodenum?
3 inches long
Where does the second part of the duodenum lie?
It ha a vertical descent.
It is next to the head of the pancreas, next to the hilum of the right kidney on psoas major
What occurs half way down the second part of the duodenum?
Half way down on the postero-medial wall (1.5 inches down) the opening of the bile and pancreatic ducts are found, this is called the major duodenal papilla
What is the role of the major duodenal papilla?
This is a common opening for the bile and pancreatic ducts
What is proximal to the major duodenal papilla?
Proximal to it is a much smaller opening (about 1 inch above) this is known as the minor duodenal papilla
What is the role of the minor duodenal papilla?
The pancreas has a main duct which opens at the major duodenal papilla but there is also a helper duct called the accessory pancreatic duct which opens at the minor duodenal papilla
How long is the third part of the duodenum?
4 inches
Where does the third part of the duodenum run?
o It runs horizontally from right psoas to left psoas, crossing the lumbar vertebral column (in front of L3) and across the front of the IVC and the aorta.
How long is the fourth part of the duodenum?
1 inch long
Where does the fourth part of the duodenum run?
It is on left psoas and curves anteriorly to become the rest of the small intestine (the jejunum and ileum)
What is the DJ flexure?
The duodenal jejunal flexure
How long is the intestine from the DJ flexure?
4-6m
40% = jejunum
60% = ileum
What suspends the jejunum and ileum?
Are they intra or retro-peritoneal?
The jejunum and ileum are suspended by the posterior wall by a mesentery and are truly intraperitoneal
What is the role of the mesentry?
It provides structure and stability (prevents twisting) and also conducts neurovascular structures from the posterior abdominal wall to the small intestine
Where is jejunum?
o Jejunum occupies the left upper quadrant
Where is the ileum?
Ileum tends to sit down in the right lower quadrant
What are the differences between the jejunum and ileum?
No clear demarcation between the two:
o The first is in their position (as above)
The jejunum is larger in diameter with a thicker wall, this is because it has more numerous mucosal folds. Thus, more absorption occurs in the jejunum
What is the difference between the mesentary of jejunum and ileum?
o There is less fat in the mesentery of the jejunum than the ileum. i.e. as you go down there is more fat mesentery
Why are the differences between mesentery in the ileum and jejunum important?
This is important because a surgeon makes a key hole incision and needs to determine if what he/she is seeing is jejunum or ileum, one of the key things they use is the amount of fat in the mesentery – if there is lots of fat one will not be able to see the vessels so well
What is at the root of the mesentery, what do they branch into?
At the root of the mesentery are arterial arcades and then long vasa recta which lead from the arterial arcade to the mucosal tube.
What are the differences in the arterial arcades in the mesentery between ileum jejunum?
§ In the jejunal part of the mesentery the arrangement is few arterial arcades and long vasa recta
In the ileal end of the mesentery there are heaps of arterial arcades stacked on top of each other with short vasa recta
Where does the ileum end?
The ileum ends at the ileo-caecal junction or ileo-caecal valve, which is mucosa covering a thick muscle sphincter to control the passage of ileal contents into the large intestine.
How long is the LI
1.5 M
What is the role of the LI?
Responsible for the absorption of water and important ions from the faeces
What are the distinguishing features of the LI from the SI?
o Position - a tube which is around the margins is large intestine
o Larger diameter – greater luminal diameter
o The small intestine has an outer longitudinal muscle coat which is continuous and an inner circular layer of smooth muscle (i.e. two distinct muscle coats)
The large intestine is different, there is a continuous layer of circular smooth muscle but the outer coat of longitudinal smooth muscle is divided into 3 discrete bands.
o Fat tags called epiploic appendices or appendices epiploice which hang off the colon
What are the three discrete bands of muscles called in the large intestine?
tenia coli
These are shorter than the mucosal tube (i.e. large intestine) thus when looking at the large intestine it is gathered up into haustra/huastrations or succulations
What is the caecum?
It is a blind ending pouch which hangs down below the ileo-ceacal junction (in the right lower quadrant)
Hanging off it is the appendix (that’s all that matters really)
What is the appendix?
This is a narrow tube of variable length – it is usually between 7 and 10 cm
Where is the appendix attached?
The base is always attached to the blind ending cecum. This is where the three tenia unite (i.e. at the base of the caecum)
What is variable about the appendix?
The variable aspect of the appendix is where the tip is found.
A pelvic appendix tips over the iliac rim and the tip of the appendix is found in the pelvis. This occurs in 20% of people.
About 65 % of people have a retrocaecal appendix
It is tucked in behind the caecum.
If appendicitis is diagnosed and the appendix can’t be found what needs to happen is to slit the peritoneum and get into a retroperitoneal position get the finger up behind the cecum and hook down the appendix from its retrocaecal position.
Order of colon
Ascending
Transverse
Descending
Sigmoid
Where does the ascending colon end?
Immediately beneath the liver it has a 90degree flexion (right colic flexure/hepatic flexure) and becomes the transverse colon
Where is the transverse colon located?
- Crosses the abdominal cavity superiorly from right to left
On the left hand side it is tucked in beneath the spleen and it turns downward to become the descending colon
Where is the descending colon, what does it become?
- Descends down the left hand side of the abdominal cavity down to the left lower quadrant
- There is an s shaped loop of colon called the sigmoid colon
- It then comes up and is centred as the rectal and anal canal – down into the pelvis
Where is the rectum located?
In the midline
What happens to the tenia in the rectum?
They spread out again
Which organs are derivatives of the gut?
Liver, gallbladder, pancreas and spleen
What are the two surfaces of the liver called?
Diaphragmatic (anteior) and visceral surface
When is the liver palpable and where?
If the liver is inflamed it becomes palpable under the costal margin
Where is the liver?
It is located in the right upper quadrant
It is related to the dome of the diaphragm
Where is the gall bladder located relative to the liver, why is this relevant in terms of a clinical examination?
- The gall bladder projects beyond the inferior border of the liver
If a patient has an inflamed gall bladder it may be possible to possible to elicit tenderness on physical examination
What divides the liver?
The falsiform ligament
What is the falsiform ligament?
It is a double layered fold of peritoneum/serous membrane
What does the falsiform ligament connect the liver to?
This connects the diaphragmatic surface of the liver to the internal aspect of the anterior abdominal wall down as far as the umbilicus
Where is the free inferior edge of the falsiform ligament?
Ligamentum teres
What is the ligamentum teres, what was its function?
It is a fibrous cord and represents the obliterated umbilical vein
This carried oxygenated blood from the placenta to the foetus in utero and used to run in the free inferior edge of the falciform ligament
What covers the liver?
Peritoneum
What happens to the top of the liver, what is this called?
- The surface of the liver is covered by peritoneum, it also reflects off the top of the liver and onto the under-surface of the diaphragm
This is called the coronary ligament
What are the most lateral edges of the coronary ligament called?
Right and left triangular ligaments
What is another name for the hilum of the liver?
The Porata hepatis
What is found at the porta hepatis?
This is where neurovascular structures and the hepatic duct which is carrying bile produced by the liver enter and exit
What is the shape of the visceral surface of the liver?
It is said to have an H shaped fissure formation with the crosspiece being formed by the Porta hepatis
What are embedded in the groves of the liver?
Gallbladder and IVC (at the back)
What are the fibrous structures forming groves in the Liver?
The Ligamentum teres and the Ligamentum venosum
Where does the ligamentum teres originate where does it run?
It has come in the free edge of the falciform ligament and is now forming a groove in the visceral surface of the liver and communicates with the left portal vein
What is the ligamentum venosum formed from?
Obliterated ductus venosum
What is the structure of vessels in the porta hepatis?
- The portal vein is behind
- The hepatic artery and duct are in front
The artery is to the left and the duct is to the right
What are the two additional lobes of the liver?
Quadrate lobe
Caudate lobe
Where is the Quadrate lobe?
Between the ligamentum teres and the gall bladder. It is square or rectangular in shape.
Where is the Caudate lobe?
Between the IVC and ligamentum venosum. It has a tail or process called the caudate process which connects it to the right lobe
What creates a free edge of the lesser omentum?
The lesser omentum stops when the duodenum turns to go back towards the posterior abdominal wall. This creates a free edge to the lesser omentum.
What runs in the free edge of the lesser omentum?
The portal triad, the 3 structures which enter or exit the Porta hepatis, get to or from this position by running in the free edge of the lesser omentum.
Thus these structures are related to the omentum as well as the C-shaped duodenum and pancreas
What is the vascular supply to the liver?
The vascular input into the liver is via the hepatic artery.
It divides into a right and left terminal branch to supply the right and left halves of the liver
Besides the hepatic artery where else does the liver receive blood from?
The liver also gets blood from the portal vein, it also divides into right and left.
Why is there no venous drainage in the perta hepatis?
Would expect to see a systemic drainage also exiting from the hilum of a structure, this is because the venous drainage of the liver by the hepatic veins (which are usually 3 in number) drain directly into the IVC. There is no point going through the hilum when the IVC is already imbedded into the visceral surface of the liver and as such the systemic veins of the liver cannot be seen outside of the liver.
What are the roles of the liver and gall bladder with regard to bile?
The liver produces it
The gall bladder stores and concentrates it
What are the bile ducts called?
- The bile enters into a duct system – the ducts of which get progressively larger and eventually form a right and left hepatic duct from the two functional halves of the liver
These join to from the COMMON HEPATIC DUCT at the porta hepatis
Where do the bile ducts run?
In the free edge of the lesser omentum
Where does the billary system open into and what are the implications?
It opens into the second part of the duodenum and thus needs to get into the retroperitoneal space
What is the route of the bile duct
- Free edge of the lesser omentum
- Behind the first part of the duodenum
- In the groove between the head of the pancreas and the 2nd part of the duodenum before it joins the pancreatic duct and empties into the major duodenal papilla
What is the common bile duct?
This is the region of the biliary system which receives input from both the gallbladder and the liver.
What is complicated about the sphincter which is associated with the Ampulla?
The sphincter surrounds both the common opening (i.e. where the ducts have combined) and also the distal portion of each of the individual ducts
Is the sphincter which surrounds the ampulla ususally closed or open?
It is usually closed, thus bile accumulates in the biliary system and back up to the gallbladder where it can be stored and concentrated
What is the shape of the gallbladder?
Pear shaped
What are the regions of the gallbladder?
Fundus, body and neck
It is the fundus which protrudes beyond the inferior margin of the liver
The neck is continuous with the duct of the gallbladder called the cystic duct
Where is the gallbaldder relative to the duodenum?
The gallbladder lies over the front of the first part of the duodenum
What are the component parts of the gallbladder?
Head
Neck
Body
Tail
Where is the head of the pancreas - what is its shape?
Within the C-shaped curve of the duodenum
The pancreas It is often called comma shaped because of the uncinate process which is a wedge shaped projection off the head
It lies posterior/deep to the superior mesenteric vessels
Where is the neck of the pancreas located?
It is over the top of the superior mesenteric vessels
Where is the body of the pancreas?
As we cross from right to left the body is above the DJ flexure
Where is the tail of the pancreas?
The tail of the pancreas takes you directly to the hilum of the spleen
What does the main duct of the pancreas drain?
The main duct of the pancreas which drains all of the pancreas except the lower portion of the head and the uncinate process
What happens to the main duct after it leaves the pancreas?
Joins with the common bile duct and then enters into the duodenum
What is the second pancreatic duct called?
Accessory pancreatic duct
What does the accessory pancreatic duct drain and where does it end?
It drains the distal portion of the head and the uncinate process
It crosses the major duodenal duct and enters the duodenum about an inch higher (seen in the previous lecture)
What is the spleen?
It is an oval shaped mass of lymphoid tissue
Where is the spleen located?
Left upper quadrant
Where does the speen lie?
- It relates to the diaphragm, it lies beneath the left dome of the diaphragm directly related to ribs 9, 10 and 11
o Its axis relates to the shaft of 10th rib
§ Thus fractures to the 9th, 10th or 11th rib could cause serious damage to the spleen and need to be treated very carefully
It receives its rich blood supply from the splenic vessels
