Abdominal Wall Flashcards
Define boundaries of abdomen and pelvis, and bony and cartilaginous landmarks visible or palpable on abdominal examination. Demonstrate descriptive regions of abdomen (four regions, nine quadrants and bloodless plane) and common incision sites. Demonstrate surface projections of abdominal organs. Describe anatomy, innervation, blood supply, lymphatic drainage and functions of the muscles of anterior abdominal wall.
Where is the abdomen?
In the region:
Below the thorax
Above the ‘true’ pelvis
The abdominal Cavity is bounded by:
Roof: Diaphragm
Walls: anterior and posterior muscles
Floor: Pelvic inlet/ pelvic floor
What is the structure of the diaphragm?
Bi-domed meaning it arches upwards into the thoracic cavity
What is the significance of the bi-domed structure of the diaphragm?
Means that part of the abdominal content lies behind the ribcage meaning it is protected
(chest wound may cause protrusion of abdominal content)
What is the inlet of the ‘true’ pelvis bounded by?
Upper border of the sacrum posteriorly and the iliopectineal line of the hip bone
What is the relation between the iliopectineal line of the hip bone and the pubic symphysis?
It leads forwards towards the upper border of the pubic symphysis
What is the iliopectineal line comprise of?
The arcute line on the ilium and the pectineal line of the pubis
What is the ilipectineal line also known as?
Pelvic brim
What is the lower limit of the pelvis bounded by?
The pelvic diaphragm
What is the pelvic diaphragm?
Transverse sheet of muscle
The abdomino-pelvic cavity is enclosed by muscle in which directions?
Anteriorly, posteriorly and laterally
Why are the lateral muscles of the abdomino-pelvic cavity referred to as anterior muscles?
They have flat tendons which run anteriorly
What does the pelvic diaphragm divide?
The pelvis from the perineum
What does the diaphragm divide?
The thorax and the abdominal organs
What is the posterior bony margin of the abdomen?
The lumbar vertebrae which sit on top of the sacrum
L1-L5
Why is the iliac known as the false pelvis?
It lies laterally to the lumbar vertebrae hence it is in the abdomen
What is the ASIS?
Anterior Superior Iliac Spine
Palpable
What is the front part of the hip bones known as?
The pubis
Which ligament forms the most anterior identifiable boundary of the anterior abdominal wall?
The inguinal ligament
What is the costal margin?
Cartilage along the edge of the eighth through tenth ribs in the middle of the chest. Where ribs 7-10 join
Which bony ribs form attachments to some abdominal wall muscles?
Tip of 11th rib
12th rib
Costal margin
What are the boundaries of the abdominal wall muscles?
Costal margin above
Inguinal ligament below
What in an identifiable boundary at the top of the abdomen?
Xiphisternum
Where does the inguinal ligament run from?
ASIS and the pubic tubercle
What is the inguinal ligament?
Infolding of the lower border of an aponeurotic tendon of the external oblique abdominis muscle of the anterior abdominal wall
How many hip bones are there?
2
How do the two hip bones attach to the sacrum?
By sacroiliac joints
Where do the two hip bones meet in the front?
Pubic symphysis
Why is the diaphragm slightly higher on the right hand side than the left hand side?
The presence of the liver
Which intercostal space does the right side of the diaphragm reach?
4th intercostal space
right nipple in males
Which intercostal space does the left side of the diaphragm reach?
5th intercostal space
below nipple in males
Where does the costal margin lead up to?
The bottom end of the breastbone
What is the name of the ridge where the anterior abdominal wall muscles meet in the midline?
Linea Alba
Why is the linea alba white?
It is relatively avascular
What is useful about the avascular nature of the linea alba?
good place to make emergency abdominal incisions
What happens to the linea alba when females become pregnant.
The placenta produces melanocyte-stimulating hormone which pigments the linea alba to become the linea nigra
What is found at the lateral borders of rectus abdominis muscle?
Linea semilunaris
What causes the linea semilunaris to form?
The fusion of aponeuroses of the anterior abdominal wall muscles either side of the rectus sheath
What planes separate the abdomen into 4 quadrants?
Paraumbilical plane
Median plane
What planes separate the abdomen into 9 regions?
Midclavicular Lines
Transpyloric plane/ subcostal plane
Trans-tubercular plane
What is the subcostal plane?
The lowest point on the costal margin
Why is the trans-pyloric plan used?
The pylorus of the stomach is relatively fixed.
Splits the abdomen into equal parts
How is the trans-pyloric plane located?
(lies midway between the supersternal notch and the pubic symphysis)
Lies a hand’s breadth below the sternum
Where is the trans-tubercular plane?
Runs between the 2 tubercles that lie on the iliac crest
What are the 9 sections of the abdomen?
Right hypochondrium Epigastric Left hypochondrium Right lumber/lateral Umbilical Left lumber/lateral Right inguinal/iliac Suprapubic Left inguinal/iliac
Where do the muscle bellies of the anterior abdominal wall muscles lie?
Laterally
Where do the aponeurotic tendons of the anterior abdominal wall muscles run?
To the midline- anteriorly
What are the anterior abdominal wall muscles?
External Oblique Abdominis
Internal Oblique Abdominis
Transversus Abdominis
Where do the anterior abdominal wall muscles fuse?
Lateral to the rectus abdominis to form the linea semilunaris
Where do the aponeurotic tendons meet?
Front of the abdomen to form the linea alba
Where does the endoabdominal fasica lie?
Inside the abdominal cavity
What lies inside the endoabdominal fascia?
Peritoneum which is a serous membrane and secretes fluid that goes into the space between the peritoneal membranes
Where does the parietal peritoneum lie?
abdominal and pelvic cavities
What is visceral peritoneum?
double fold of peritoneum that wraps around viscera
What is the mesentery?
Connecting stalk of peritoneum that attaches organs to the body wall
What are the layers of the abdomen?
Skin
Superficial Fascia
Deep Fascia
What are the two layers of superficial fascia in the abdomen?
Camper’s fascia
Scarpa’s fascia
What is contained within the superficial fascia?
Cutaneous blood vessels and cutaneous nerves
What are intraperitoneal organs?
Organs that are surrounded by peritoneum
Why are intraperitoneal organs mobile?
They have a mesentery which gives them flexibility
What are retroperitoneal organs?
Organs that are behind the peritoneal cavity- relatively immobile
What is the Camper’s Fascia?
Fatty layer of connective tissue- thick, semi-fluid and variable
How far down does Camper’s fascia travel?
To the inguinal ligament- after that is the superficial fascia of the thigh
What is the composition of Scarpa’s fascia?
Membranous not fatty
Where is Scarpa’s fascia particularly located?
Lower abdomen particularly on the anterior abdominal wall and is continuous into the perineum where the genitalia lie
What is the function of Scarpa’s fascia?
Keeps fluids away from the genital region
What is the feature of Scarpa’s fascia?
Semipermeable membrane which is resistant to fluid
What is sometimes incised to gain access to retroperitoneal organs?
Lumber fascia
Where does the rectus abdominis run?
Straight down from chest to pubis
What does the rectus abdominis do?
Draws the trunk downwards- helps flex the muscles
Where does the external oblique run?
From the chest wall and runs downwards, forwards and medially to the midline
How is the inguinal ligament formed?
By the external abdominal oblique aponeurosis that is flipped over
What does the external oblique do?
Draws the chest/trunk down to the opposite side
Where is the internal oblique?
Inside the external oblique
In what direction do the fibres of the internal oblique run?
Downwards and laterally
As you go down the muscle fibres become more horizontal
Where does the internal oblique attach?
Iliac crest and lateral third of the inguinal ligament
What does the internal oblique muscle do?
Ipsilateral movement- left internal oblique brings abdomen to the left along with right external oblique
What does the transversus abdominis do?
Compress the abdomen
Where does the transversus abdominis run?
From the lateral third of the inguinal ligament, iliac crest posteriorly and attaches to the ribs and the lumber fascia
Horizontally
What forms the conjoint tendon?
The lower part of the common aponeurosis of the internal abdominal oblique and the transverse abdominal
What forms the anterior layer of the rectus sheath?
External Oblique
What happens to the internal oblique in the rectus sheath?
It splits into 2, one half goes behind the rectus and the other goes in front
What happens at the Arcuate line (Douglas’ line)?
All the aponeurotic tendons come anteriorly which leaves behind the transversalias fascia which creates a ridge at the back of the rectus abdominis
What is the purpose of the Arcuate line?
Allows the inferior epigastric artery to gain access to the back of rectus abdominis
What is the nerve supply of the abdomen?
Supplied segmentally from cutaneous branches of T7 through to L1
What supplies the umbilicus?
T10
What is a dermatome?
An area of the skin supplied by nerves from a single spinal root
What supplies the rectus abdominis?
T7-T12
What supplies the internal oblique and Transversus Abdominis?
T7-L1
What supplies the external oblique?
T7-T12
What is the first branch of L1?
Ilioinguinal nerve
What does the ilioinguinal nerve do?
Supplies the conjoined tendon
Where does the iliohypogastric nerve arise from?
L1
What does the iliohypogastric nerve do?
Cutaneous supply
Where do the superficial veins of the abdomen lie?
Camper’s fascia
Where do the veins of the abdomen originate from?
The umbilicus- paraumbilical
Where do the veins of the abdomen drain?
Upwards- thoraco-epigastric/ thoraco-abdominal veins
Downwards- Superficial epigastric
Where do the Thoraco-epigastric veins connect?
Around the breast- lateral thoracic veins
Where do the superficial epigastric veins drain?
Into the femoral vein along with the superficial circumflex iliac veins
where do the lymphatics above the umbilicus drain?
Axillary nodes
where do the lymphatics below the umbilicus drain?
Superficial inguinal nodes
