Anatomy of the Abdominal Wall, Inguinal Region & Hernias Flashcards
What are the bony landmarks of the pelvis
Iliac Crest: most superior border of the ilium
Iliac Fossa: internal face of the ilium
Anterior Superior Iliac Spine: protrusion at the most anterior part of the iliac crest
Pubic Symphysis: cartilage where the pubic tubercles are joined
Pelvic Inlet: enclosed laterally by the pelvic brim, anteriorly by the pubic tubercles and posteriorly by the sacrum
Describe the skeletal landmarks of the abdomen/thorax
Sternum/Xiphoid process: XP at TIX/X
Costal Cartilage: of the 6th-10th ribs forms the costal margin to which the diaphragm is attached
Which vertebrae are associated with the abdomen and pelvis
Thoracic, lumbar vertebrae, sacrum
Describe the abdominopelvic cavity
Abdominal and pelvic cavities are continuous
Diaphragm separates the thoracic and abdominal cavities.
Upper part of the abdominal cavity extends beneath the thoracic cage
Pelvic inlet (pelvic brim) arbitrarily separates the abdominal from the pelvic cavity
Why is some of the abdomen protected by the thoracic wall
note that due to the arching of the diaphragm the upper abdomen extends into the thorax and may be protected by the ribcage
Describe the axis of the pelvic cavity
Downwards and backwards
Describe the pelvic inlet
The circular margin of the pelvic inlet is formed posteriorly by the sacrum, anteriorly by the pubic symphysis and laterally by the distinct bony rim of pelvic bone
What is a consequence of the pelvic cavity being continuous with the abdominal cavity
The peritoneum lining the abdominal cavity is continuous with that of the pelvic cavity- infections in one region can freely spread to the other
Bladder expands superiorly from the pelvic cavity into the abdominal cavity
During pregnancy, uterus expands superiorly into the abdominal cavity
List the visceral structures in the abdomen
Stomach, duodenum, small and large intestines
Liver, pancreas & spleen
Kidneys, ureters and urinary bladder
Reproductive organs
Abdominal vessels
Spleen in a lymphatic organ
Structures belonging to G.I system, urinary system and reproductive system
What do the kidneys, ureter and bladder extend into
The pelvic cavity.
Describe how we can divide the abdomen into 9 regions anteriorly
Superior horizontal plane is the subcostal plane (lower border of the costal cartilage of rib 10, passing posteriorly through L3)
Inferior horizontal plane is the intertubercular plane ( connects the tubercules of the iliac crests which are palpable, passes through the upper part of L5)
The vertical lines are the mid clavicular lines
What is sometimes used instead of the subcostal plane
The transpyloric plane
Found halfway between jugular notch and the symphysis pubis or halfway between the umbilicus and the inferior end of the body of the sternum
Passes posteriorly through the body of L1
Intersects with the costal margin at the ends of the 9th costal cartillage
What are the 9 regions
Superiorly: right hypochondrium, epigastric region (referred pain from foregut), left hypochondrium
Inferiorly: Right flank/lumbar, umbilical (referred pain from foregut), left flank/lumbar
Inferiorly again: right groin, hypogastric/suprapubic region (referred pain from foregut), left iliac region
Where are the inguinal ligaments found
left and right groin
Describe the 4 quadrants of the abdominal wall
Horizontal umbilical plane passing through the umbilicus and the intervertebral disc between vertebrae L3 and L4 and intersecting with the vertical median plane divides the abdomen into 4 quadrants:
Right upper, left upper, right lower and left lower
What structures are present in each quadrant
Right Upper Quadrant
Liver and gallbladder
Left Upper Quadrant
Stomach and spleen
Right Lower Quadrant
Cecum and appendix
Left Lower Quadrant
Sigmoid colon and descending colon
List the structures of the antero-lateral abdominal wall
Several surface features
Costal margin, xiphoid
process, iliac crest, ASIS, pubic symphysis and tubercle
Umbilicus, epigastric fossa,
Rectus abdominis, linea alba, linea semilunaris
Abdominal wall muscle sheets
Describe the superficial of the abdominal wall
Layer of fatty connective tissue- single layer and is continuous with the superficial fascia throughout other regions
Below the umbilicus- if forms two layers: as superficial and deeper and membranous layer
Superficial fatty layer (Camper’s Fascia) is continuous over the inguinal ligament
Describe the deeper membranous layer
Scarpa’s fascia- little to no fat
Investing (deep) fascia between the oblique muscles
Summarise the muscles in the abdominal wall
Anterior wall
Paired vertical rectus abdominis muscles within rectus sheath
Lateral wall - 3 flat sheet muscles
External oblique
Internal oblique
Transversus abdominis
Posterior wall
Post vertebral muscles –erector spinae group
Psoas, quadratus lumborum and iliacus muscles
Summarise the three flank muscles
The three muscles are separate in the flanks
The three flat muscle fibres continue anteriorly as aponeurotic sheets and contribute to the rectus sheath
What are the functions of the flank muscles
Compress the abdomen and increase the intra-abdominal pressure to aid forced expiration, and evacuation of urine, faeces, parturition, heavy lifting
Supports viscera – “guarding” mainly the intestines
Flex and rotate the trunk
Protects the viscera from injury and helps maintain the position of the viscera in the erect posture against the action of gravity.
Contraction of these muscles in forced and quiet expiration pushes the viscera upwards and helps push the relaxed diaphragm further upwards- also plays a role in coughing and vomiting.