Anterior Abdominal Wall Flashcards
What muscles comprise the anterior wall?
Superficial: external oblique (EO), (aponeurosis of EO)
Deep: rectus abdominus, internal oblique
Other: transversus abdominus (linea alba)
Describe the 4 quadrant pattern
4 quadrants
- right upper
- left upper
- right lower
- left lower
left/right separated by median plan
upper/lower separated by transumbilical plane
What are the aponeurotic divisions of the anterior abdominal wall
rectus sheath
linea alba
Describe the layers of the anterior abdominal wall
from superficial to deep
- Skin
- Camper’s fascia (superficial fatty layer of subcutaneous tissue)
- Scarpa’s fascia (deep membraneous layer of subcutaneous tissue)
- External oblique m (surrounded by investing (deep) fasicia)
- Internal oblique m (deep fasicia underneath)
- Transversus abdominis m
- Endo-abdominal (transversalis) fasicia
- Extraperitoneal fat
- Parietal peritoneum
Describe the rectus sheath
- aponeurotic (tendinous) sheath envelops rectus abdominus and pyramidalis mm
- consists of anterior and posterior layers
- anterior layer is in front of rectus abdominis m, posterior is behind rectus abdominis
- superior and inferior portions are relative to arcuate line
How does the composition of the rectus sheath differ above the arcuate line vs. below the arcuate line?
Above the arcuate line: the anterior layer of sheath is formed by aponeuroses of EO and 1/2 of IO. The posterior layer of the sheath is formed by aponeuroses of 1/2 of IO, all of transersus abdominis and transversalis fascia
Remeber the anterior layer is in front of rectus abdominis m while the posterior layer is behind rectus abdominis m.
Below the arcuate line: The anterior layer of the sheath is formed by aponeuroses of EO, IO and transersus abdominis. The posterior layer of the sheath is formed by transversalis fascia
Describe the neurovascular supply of the anterior abdominal wall
- superficial vessels
- deep circumflex iliac vessels
- inferior epigastric vessels
- superior epigastric vessels
- musculophrenic vessels
- nerves: ventral rami of T7-L1 spinal nn
Describe the inguinal region
inferior lateral abdominal region
- superior to thigh
- medial to ilium
- lateral to pubic bone
area extends between anterior superior iliac spine (ASIS) and pubic tubercle
Describe the gender distinctions for the inguinal canal
They contain different contents based on reproductive organs and genitalia
Describe the rings of the inguinal canal
-
Superficial Ring : opening in EO aponeurosis
- obvious triangular opening lateral to pubic tubercle
-
Deep Ring : opening in transversalis fascia
- subtle piercing just lateral to inferior epigastric vessels
NOTE: Canal extends between superficial and deep rings
Describe the difference between an indirect and direct inguinal hernia
Indirect inguinal hernias extend thru the _inguinal cana_l while direct inguinal hernias extend thru the inguinal triangle and are associated with weakened abdominal wall. *Indirect *inguinal hernias are lateral to inferior epigastric vessels while direct inguinal hernias are medial to inferior epigastric vessels.
indirect inguinal hernias are the most common type
What are the other common types of abdominal hernias
- Femoral hernia
- Umbilical hernia
- Epigastric hernia
Note: most common type in ♀ : indirect inguinal
Describe an abdominal hernia
- Outpouching of abdominal viscera within a sac
- Hernial sac composed of 3 layers
- peritoneum
- extraperitoneal fat
- transversalis fascia
- ~90% of hernias occur in inguinal region
Define the arcuate line
- Midway between the umbilicus and pubic symphysis.
- Structure of the rectus sheath changes relative to it.
Rectus sheath superior to arcuate line
Anterior layer: formed by aponeuroses of EO and 1/2 IO
Posterior layer: formed by aponeuroses of 1/2 IO & TA and transversalis fascia
Rectus sheath inferior to arcuate line
anterior layer: formed by aponeuroses of EO, IO and TA
posterior layer: formed by transversalis fascia
Describe the 9 quadrant pattern
- right hypochondrium
- epigastric region
- left hypochondrium
- right flank
- umbilical region
- left flank
- right groin
- pubic region
- left groin
2 midclavicular planes (vertical)
subcostal plane (superior horizontal)
intertubercular plane (inferior horizontal)
Describe the infraumbilical peritoneal folds
- median umbilical fold
- 2 medial umbilical folds
- 2 lateral umbilical folds
Median umbilical fold
- from urinary bladder to umbilicus
- covers median umbilical ligament
Medial umbilical folds
- 2 of them
- covers medial umbilical ligaments
- occluded portions umbilical aa
Lateral umbilical folds
- 2 of them
- covers inferior epigastric vessels
Superficial vessels
- superficial circumflex Iliac a.
- superficial circumflex Iliac v.
- superficial epigastric a.
- superficial epigastric v.
Note: run in superficial fat and fascia
Superficial circumflex Iliac a.
- branch of femoral a.
- supplies region of inguinal ligament
Superficial circumflex Iliac v.
- drains to femoral v.
- drains region of inguinal ligament
Superficial epigastric a.
- branch of femoral a.
- supplies abdomen inferior to umbilicus
Superficial epigastric v.
- drains to femoral v.
- drains abdomen inferior to umbilicus
Deep Circumflex Iliac a.
- branch of external Iliac a.
- runs between inferior oblique m and transversus abdominis m.
- supplies inferior lateral abdominal mm.
Deep circumflex Iliac v.
- drains to external iliac v.
- runs between inferior oblique and tranversus abdominis mm.
- drains inferior lateral abdominal mm.
Inferior epigastric a
- branch of external Iliac
- enters posterior rectus sheath at arcuate line
- supplies lower rectus abdominis mm
- anastomoses with superior epigastric a.
Inferior epigastric v.
- drains to external Iliac v
- enters posterior rectus sheath at arcuate line
- drains lower rectus abdominis mm
Superior epigastric a
- branch of internal thoracic a. (mammary)
- enters posterior rectus sheath lateral to sternum
- supplies upper rectus abdominis mm
- anastomoses with inferior epigastric
Superior epigastric v
- drains to internal thoracic v
- enters posterior rectus sheath lateral to sternum
- drains upper rectus abdominis muscles
Musculophrenic a.
- branch of internal thoracic (mammary)
- runs along costal cartilages
- supplies upper abdominal mm and diaphragm
Musculophrenic v.
drains to internal thoracic v runs along costal cartilages drains upper abdominal mm and diaphragm
Nerves of Abdominal Wall
- ventral rami of T7-L1 spinal nn
- run between IO and TA mm
Nerve(s) that supply region above the umbilicus
- T7
- T8
- T9
Nerve(s) that supply umbilical region
- T10
Nerve(s) that supply region below umbilicus
- T11
- T12
- L1
Injury to what 3 nerves weakens mm in inguinal region, leading to a predisposition to developing direct inguinal hernias?
- T11, T12 and L1
Describe the inguinal ligament
- Folded inferior border of the EO aponeurosis
- Extends from ASIS to pubic tubercle
Inguinal canal
- Obliquely set tunnel 3 to 5 cm long
- Traverses antertior abdominal wall
- Runs parallel & superior to inguinal ligament
Describe the Male Inguinal Canal
- Contains spermatic cord & its contents
- (vas deferens, testicular nn & vessels, cremasteric m & fascia
- Ilioinguinal n. (L1)
Describe the female Inguinal Canal
- Contains round ligament of uterus
- corresponds to spermatic cord in males
- Ilioinguinal n. (L1)
Describe the walls of the inguinal canal
- Anterior wall :EO aponeurosis
-
Posterior wall : transversalis fascia & conjoint tendon
- fusion of IO, TA aponeuroses medially
- Roof : IO & TA muscles (superior)
- Floor : inguinal ligament (inferior)
Describe the inguinal triangle
- also known as Hesselbach’s triangle
- contains
- inferior epigastric a.
- rectus abdominus m.
- inguinal ligament
Describe an indirect inguinal hernia
- extends thru entire inguinal canal
- lateral to inferior epigastric vessels
- commonly enters scrotum or labia majora
-
most common type of hernia
- more in ♂ than ♀
- usually from persistent processus vaginalis in ♂
- connects peritoneum with descended testis
- referred to as canal of Nuck in ♀
Describe a direct inguinal hernia
- thru inguinal triangle (Hesselbach’s)
- inferior epigastric a., rectus abdominus m. & inguinal ligament
- emerges thru conjoint tendon by or at superficial ring
- medial to inferior epigastric vessels
- usually does not enter scrotum or labia majora
- more common in ♂ than ♀
- usually associated with weakened abdominal wall
Describe a femoral hernia
- thru femoral ring & canal
- medial compartment of sheath
- _more common in ♀_than ♂
- femoral ring is wider in♀
Describe an umbilical hernia
- thru umbilical ring
- most common in newborns
- more common in ♀ & obese individuals
Describe an epigastric hernia
- thru linea alba
- most common in over 40
- usually assoc. with obesity
