1. Anatomy of the Abdominal wall, Inguinal Region and Hernias Flashcards
What are the bony landmarks of the abdomen?
Sternum and xiphoid process
Costal margin, costal cartilages and ribs
Iliac crest, iliac fossa and anterior superior iliac spine (ASIS)
Pubic symphysis, pubic tubercle and pubic ramus
Thoracic and lumbar vertebrae, sacrum and pelvic bones
Describe the the Abdominopelvic cavity
Abdominal and pelvic cavities are continuous
What separates the thoracic and abdominal cavities?
Diaphragm
What arbitrarily separates the abdominal from the pelvic cavity?
Pelvic inlet (pelvic brim)
Axis of abdominal cavity
Vertical
Axis of pelvic cavity
Downwards and backwards
What visceral structures are found in the abdominopelvic cavity?
Stomach, duodenum, small and large intestines Liver, pancreas and spleen Kidneys, ureters and urinary bladder Reproductive organs Abdominal vessels
What are the 9 regions that the abdomen can be divided into (from top right to bottom left)?
Right hypochondriac, epigastric, left hypochondriac
Right lumbar, umbilical, left lumbar
Right iliac, hypogastric/suprapubic, left iliac
What planes are used to divide the abdomen into 9 regions?
Mid-clavicular planes Subcostal plane (L2) Intertubercular plane (L5)
How is the abdomen divided into 4 quadrants?
Vertical line down sagittal plane
Horizontal line across transumbilical plane
What muscles make up the anterior wall of the abdomen?
Paired vertical rectus abdominal muscles within the rectus sheath.
What muscles make up the lateral wall of the abdomen?
External oblique
Internal oblique
Transversus abdominis
What muscles make up the posterior wall of the abdomen?
Quadratus lumborum, psoas major and iliacus muscles
Post-vertebral muscles (erector spinae group)
What is the midline of the abdominal wall called?
Linea alba
What are the 2 fascia found immediately below the skin and what are their characteristics?
Camper’s Fascia: superficial fatty layer of subcutaneous tissue
Scarpa’s Fascia: deep membranous layer of subcutaneous tissue
Where do the 3 flank sheet muscles continue anteriorly?
As aponeurotic sheets
Contribute to the rectus sheath
Name 3 functions of the 3 sheet-like muscles
Compresses the abdomen and increases intra-abdominal pressure to aid expiration and evacuation of faeces, urine, parturition and heavy lifting.
Supports viscera - guards the intestines
Flex and rotate the trunk
What happens to the 3 flank muscles when they reach the anterior midline?
They become aponeurotic
Thin but strong fibrous sheets of tissue that replaces a tendon in muscles that are flat and sheet-like and have a wide area of attachment.
Fuse together to form an envelope around the rectus abdominus muscle (rectus sheath)
What are the attachments of the external oblique?
External surfaces of the bottom 8 ribs
Free posterior border
Fans out to Xiphoid process, linea alba, pubic crest and tubercle, anterior 1/2 of the iliac crest
State the direction of the external oblique muscle fibres.
Infero-medially
Downward and forward
How is the inguinal ligament made and where does it attach?
Formed by the rolling inwards of the lower aponeurotic border of the external oblique.
Extends from the anterior superior iliac spine (ASIS) to the pubic tubercle
Where do aponeurosis of external oblique fuse?
Medially with rectus sheath
What are the attachments of the internal oblique?
Laterally: thoracolumbar fascia anterior 2/3 of iliac crest lateral 1/2 of inguinal ligament Medially: lower 3 ribs and costal cartilages, xiphoid process rectus sheath conjoint tendon
State the direction of the muscle fibres of the internal oblique.
Infero-laterally
Downward and backward
What are the attachments of the transversus abdominis?
Laterally: bottom 6 costal cartilages thoracolumbar fascia anterior 2/3 of the iliac crest lateral 1/3 of the inguinal ligament Medially: xiphoid process linea alba (rectus sheath) pubic symphysis conjoint tendon
State the direction of the muscle fibres of the transversus abdominis.
Horizontally
Where does the neurovascular plane lie?
Between the internal oblique and the transversus abdominis
What are the points of attachment of the rectus abdominis?
Superior: 5-7 costal cartilages xiphoid process Inferior: Pubic symphysis pubic crest
What structures divide the rectus abdominis into segments?
Transverse tendinous intersections (which are attached to the anterior wall of the rectus sheath)
3 on each side
Describe the rectus abdominis muscle
Long strap muscle of the anterior abdominal wall enclosed in rectus sheath
2 heads
What is the rectus sheath formed by?
The aponeuroses of the 3 flat muscles
Describe the arrangement of the rectus sheath above and below the arcuate line.
Above the umbilicus: internal oblique aponeurosis splits to encase the rectus abdominis.
The external oblique aponeurosis is anterior to the rectus sheath and the transversus abdominis is posterior to the rectus abdominis.
Below the umbilicus (at arcuate line): all 3 sheet muscles are anterior to the rectus abdominis
The posterior surface of rectus abdominis is in contact with the transversalis fascia.
What is the function of the rectus abdominis?
The most powerful flexor of the vertebral column
External and internal obliques of both sides important in this
Where do the rectus sheaths meet?
In the midline
Linea alba
What are the points of attachment of quadratus lumborum?
Lower border of the 12th rib
Transverse process of 5th lumbar vertebra
Adjacent iliac crest
What are the points of attachment of psoas major?
Bodies of all 5 lumbar vertebra
Lesser trochanter of the femur
What is the function of the posts major?
Flexor of hip and trunk