Abdomen: Abdominal Wall Flashcards
Abdominal cavity extends from
- Thoracic diaphragm superiorly
- To pelvic inlet inferiorly
Abdominal cavity is continuous with
- Pelvic cavity (abdominopelvic cavity)
Abdominal muscles/aponeuroses form a
- Non-rigid anterior and lateral wall
Ribs overly some
- Abdominal viscera
- Rib fracture can damage abdominal viscera
Structures that form the posterior abdominal wall
- Lumbar vertebrae
- IVD
- Pelvis
- Muscles
Abdominal cavity contains organs of
- GI tract
- Urogenital tract
9 abdominal regions formed by these 4 planes
- 2 midclavicular planes
- Subcostal plane
- Transtubercular (intertubercular) plane
Subcostal plane located at level of
- L3 vertebral body
Transtubercular (intertubercular) plane located at level of
- L5 vertebral body
Abdominal quadrants formed by 2 planes
- Transumbilical plane
- Median plane
Transumbilical plane located at level of
- L3/4 disc
Transpyloric plane
- Midway between manubrium and pubic symphysis
- Transects pylorus
Transpyloric plane located at level of
- L1 vertebral body
Supracristal plane located at level of
- L4 vertebral body
Layers of anterolateral abdominal wall (11)
- Skin
- Superficial fascia
- Deep fascia (investing)
- External oblique muscle
- Deep fascia (investing)
- Internal oblique muscle
- Deep Fascia (investing)
- Transversus abdominis
- Endoabdominal fascia
- Extraperitoneal tissue (fat)
- Parietal peritoneum
Superficial fascia (subcutaneous fascia) has 2 layers
- Camper fascia (fatty layer)
- Scarpa fascia (fibrous layer)
Endoabdominal fascia also called
- Transversalis fascia
Abdominal muscles
- External oblique (EO)
- Internal oblique (IO)
- Transversus abdominis (TA)
- Rectus Abdominis (RA)
External/Internal oblique muscle fibers run
- Perpendicular to each other
- Similar to plywood
- Fiber direction is important in muscle sparing incisions
Aponeurosis
- Broad, flat sheet of fibrous connective tissue that functions like a tendon
Anterior continuation of EO, IO, and TA aponeuroses forms
- Linea semilunaris
- Rectus sheath
- Midline raphe
- Intersection with contralateral aponeuroses
Linea semilunaris is located
- Lateral to rectus abdominis
Midline raphe (linea alba) extends
- Xiphoid to pubic symphisis
- Between rectus abdominis
Midline raphe (linea alba) is a good incision point because
- It is avascular
Rectus abdominis inferior attachment
- Pubic symphysis/crest
Rectus abdominis superior attachments
- Xiphoid process
- 5-7th ribs
Rectus abdominis muscle segments are
- Separated tendinous intersections
External oblique attachment points
- Ribs 5-12
- Linea alba, pubic tubercle/crest, iliac crest, ASIS
Internal oblique attachment points
- Thoracolumbar fascia, iliac crest
- Ribs 10-12, linea alba, pubic bone
Transversus abdominis attachment points
- Lower ribs, thoracolumbar fascia, iliac crest
- Linea alba, pubic bone
Pyramidalis muscle
- Small, triangular muscle
- Absent in ~20% of people
Rectus abdominis and external oblique do NOT attach to
- Thoracolumbar fascia
Rectus sheath
- Fibrous compartment
- Formed by aponeuroses of EO, IO, TA
Arcuate line
- Demarcation of change in sheath structure
- Located 1/3 distance between umbilicus to pubic symphysis
Anterior wall above arcuate line
- EO aponeurosis
- Anterior lamina of IO aponeurosis
Posterior wall above arcuate line
- Posterior lamina of IO aponeurosis
- TA aponeurosis
Anterior wall below arcuate line
- Aponeuroses of all muscles
Posterior wall below arcuate line
- None really
- Only transversalis fascia and peritoneum
Posterior layer of rectus sheath is absent
- Above the costal margin
Rectus sheath contains
- Rectus abdominis
- Pyramidalis muscle
- Sup. and inf. epigastric vessels
Sensory innervation of abdominal wall involves
- Ventral rami T7-11
- Subcostal nerve (T12)
- Ventral rami of L1
Ventral rami T7-11
- Thoracoabdominal nerves
- Lateral and anterior cutaneous branches
Ventral rami T10 supplies
- The umbilicus area
Ventral rami of L1 branches into
- Iliohypogastric nerve (ventral rami L1)
- Ilioinguinal nerve (ventral rami L1)
Ilioinguinal nerve (ventral rami L1) supplies
- Inguinal region
- Anterior scrotum/labia majora
Motor innervation to the abdominal muscles is
- The same as sensory
Blood supply of the abdominal wall
- Superior epigastric
- Inferior epigastric
- Superficial epigastric
- Superficial circumflex iliac
- 10th and 11th posterior intercostals
- Subcostal
- Lumbar arteries
Superior epigastric artery is a branch off
- Internal thoracic artery
Inferior epigastric is a branch off
- External iliac artery
Branches off femoral artery
- Superficial epigastric
- Superficial circumflex iliac
Branches off the aorta
- 10th/11th posterior intercostals
- Subcostal
Superior & inferior epigastric enter rectus sheath
anastomose
- Around umbilicus
Superior & inferior epigastric enter rectus sheath provide the pathway of
- Collateral circulation in aortic stenosis/occlusion
Deep venous drainage of abdominal wall (mirrors arterial supply)
- Superior epigastric vein (internal thoracic vein)
- Inferior epigastric vein (external iliac vein)
Superficial venous drainage
- Multiple superficial veins
- Superficial epigastric (great saphenous vein)
Thoracoepigastric vein
- Communicates w/ axillary and saphenous veins
- Saphenous vein drains into the femoral vein
- Provides a collateral pathway when IVC or portal
Abdominal wall lymph drainage above umbilicus
- Anterior axillary nodes
Abdominal wall lymph drainage below umbilicus
- Superficial inguinal nodes
Anterolateral abdominal wall contains
- Peritoneal folds
- Fossae
- Falciform ligament
Peritoneal folds
- Median umbilical fold (ligament)
- Medial umbilical fold (ligament)
- Lateral umbilical fold
Median umbilical fold (ligament)
- Remnant of the urachus
Medial umbilical fold (ligament)
- Obliterated umbilical arteries
Lateral umbilical fold
- Inferior epigastric vessels
Fossae of the anterolateral abdominal wall are
- Depressions between umbilical folds
3 fossae of the anterolateral wall
- Supravescial
- Medial inguinal
- Lateral inguinal
Supravescial fossa
- Between median and medial fold
- Related to the bladder
Medial inguinal fossa
- Between medial and lateral folds
- Inguinal triangle (Hesselbach triangle)
- Site of direct inguinal hernia
Lateral inguinal fossa
- Lateral to lateral folds
- Location of deep inguinal ring
- Site of indirect inguinal hernia
Falciform ligament
- Peritoneal reflection between liver and anterior/superior abdominal wall
Falciform ligament contains
- Round ligament of liver (ligamentum teres hepatis)
- Paraumbilical veins
Round ligament of liver (ligamentum teres hepatis)
- Remnant of umbilical vein
