Region 2 - Abdominal Walls Flashcards
Where is the trans-umbilical plane?
IV disc between L3 and L4
What are the 2 divisions of the abdominal superficial fascia below the umbilicus?
Superficial (fatty) - Camper’s fascia
Deep (membranous) - Scarpa’s fascia
What layer of abdominal fascia is continuous over the inguinal ligament and into the fascia of the thigh and perineum?
Camper’s (superficial fatty) fascia
How does Camper’s fascia contribute to the structure of the penis?
Loses fatty layer
Fuses with deeper layer (Scarpa’s fascia)
Becomes dartos fascia of scrotum
How does Camper’s fascia contribute to the female external genitalia?
Retains fatty layer
Contributes to fascia of labia majora
Where does the Scarpa’s fascia attach in the abdomen?
Pubic symphysis
Linea alba in midline
What does Scarpa’s fascia attach to in the perineum?
Posterior part of perineal membrane
- Superficial part ie Colles’ fascia
What does Scarpa’s fascia contribute to in the male external genitalia?
Fascia of penis
Dartos fascia of scrotum
Fundiform ligament of penis
What does Scarpa’s fascia contribute to in the female external genitalia?
Labia majora
What direction do the external oblique fibres run in?
Inferomedially (hands in pockets)
What is the origin of the external obliques?
Ribs 5-12
Where do the external obliques insert?
Iliac crest
Linea alba
Where does the external oblique aponeurosis run from and to?
From xiphoid
To pubic symphysis
What does the lower border of the external oblique aponeurosis form?
Inguinal ligament
What are the functions of the external obliques?
Flex trunk by using both
Turn to ipsilateral side by using one
What innervates the external obliques?
Anterior rami T7-T12 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
What direction do the fibres of the internal obliques run in?
Superomedially
What are the origins of the internal obliques?
Thoracolumbar fascia
Inguinal ligament
Iliac crest
What are the insertions of the internal obliques?
Ribs 9-12
Where does the aponeurosis of the internal obliques end?
Linea alba
Pectineal line
Pubic crest
What are the functions of the internal obliques?
Flex trunk by using both
Bend trunk to one side by using one
What innervates the internal obliques?
Anterior rami T7-L1 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
- Iliohypogastric and ilioinguinal nerves (L1)
What are the origins of the transversus abdominis?
Thoracolumbar fascia
Iliac crest
Inguinal ligament
Costal cartilages of ribs 7-12
What are the insertions of the transversus abdominis?
Linea alba
Pubic crest
Pectineal line
What innervates the transversus abdominis?
Anterior rami T7-L1 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
- Iliohypogastric and ilioinguinal nerves (L1)
What is the function of the transversus abdominis?
Support abdominal wall
What are the origins of the rectus abdominis?
Pubic tubercle
Pubic crest
Pubic symphysis
What are the insertions of the rectus abdominis?
Xiphoid process
Costal cartilages of ribs 5-7
What are the functions of the rectus abdominis?
Flexes trunk
Supports/Compresses abdominal wall
What innervates the rectus abdominis?
Anterior rami T7-T12 via:
- Thoracoabdominal nerves (T7-T11)
- Subcostal nerve (T12)
What is the origin of the pyramidalis?
Pubis
What is the insertion of the pyramidalis?
Linea alba
What is the function of the pyramidalis?
Tenses linea alba
What innervates the pyramidalis?
Anterior ramus T12 (subcostal nerve)
Where does the rectus sheath lie above the costal margin?
Directly on costal cartilage
Where is the arcuate line?
Half way between umbilicus and pubic bone
What is the structure of the rectus sheath above the arcuate line?
Aponeuroses of external oblique and half of internal oblique are anterior to rectus abdominis
Aponeuroses of half of internal oblique and transversus abdominis are posterior to rectus abdominis
What is the structure of the rectus sheath below the arcuate line?
All aponeuroses anterior to rectus abdominis
From superficial to deep, what are the layers of the abdominal wall?
Skin
Superficial (fatty) layer of superficial fascia (Camper’s)
Deep layer of superficial fascia (Scarpa’s)
Muscles and deep fascia
Transversalis fascia
Extraperitoneal fat
Parietal peritoneum
What is the median umbilical ligament?
Remnant of urachus
What are the medial umbilical ligaments?
Remnants of umbilical arteries
What do the lateral umbilical folds contain?
Inferior epigastric vessels
What nerves supply the anterior abdominal wall?
Lateral cutaneous branches of intercostal nerves 7-11 (T7-T11), subcostal nerve (T12) and iliohypogastric and ilioinguinal nerve (L1)
Anterior cutaneous branches of T7-T12
What is the arterial supply of the anterior abdominal wall?
Musculophrenic artery (from internal thoracic)
Femoral artery branches:
- Superficial epigastric
- Superficial circumflex iliac
What is the superficial lymphatic drainage of the anterior abdominal wall?
Superficial inguinal
Anterior axillary
Posterior axillary
What is the deep lymphatic drainage of the anterior abdominal wall?
Parasternal nodes (internal thoracic artery) Lumbar nodes (abdominal aorta) External iliac nodes
Where does the inguinal canal lie?
Superiorly to the medial half of the inguinal ligament
How long is the inguinal canal?
~4cm
What does the inguinal canal carry generally in males?
Structures to/from testis and abdomen
Ilioinguinal nerve
What does the inguinal canal carry generally in females?
Round ligament of uterus to labia majora
Ilioinguinal nerve
What is the superficial inguinal ring?
Triangular-shaped defect in external oblique aponeurosis
What forms the base of the superficial inguinal ring?
Pubic crest
What are the margins of the superficial inguinal ring attached to?
Lateral crus to pubic tubercle
Medial crus to pubic crest
What does the superficial inguinal ring give rise to?
External spermatic fascia
What forms the intercrural fibres of the superficial inguinal ring?
Superficial layer of deep fascia over external oblique
Where do the intercrural fibres lie in the superficial inguinal ring?
Superolaterally
What is the function of the intercrural fibres?
Support the superficial inguinal ring
What ligament can become fibrous and blend with the superficial inguinal ring?
Round ligament
What is the deep inguinal ring?
Oval opening in the transversalis fascia
Where is the deep inguinal ring located?
Halfway between ASIS and pubic symphysis (~1.3cm above inguinal ligament)
Where do the inferior epigastric vessels lie in relation to the deep inguinal ring?
Medially
What fascia does the deep inguinal ring give rise to?
Internal spermatic/round ligament
What forms the anterior wall of the inguinal canal?
External oblique aponeurosis
Internal oblique muscle fibres:
- In lateral third (weak area of deep ring in post. wall)
What forms the posterior wall of the inguinal canal?
Transversalis fascia
Conjoint tendon:
- In medial third (weak area of superfic. ring in ant. wall)
What is the conjoint tendon?
Common insertion of internal oblique and transversus abdominis
Where does the conjoint tendon insert?
Pubic crest
Pectineal line
What forms the roof of the inguinal canal?
Transversalis fascia laterally
Internal oblique and transversus abdominis muscle fibres centrally
What forms the floor of the inguinal canal?
Inguinal ligament Lacunar ligament (medial)
Where does the lacunar ligament originate and what direction does it move in?
Medial end of inguinal ligament
Superoposteriorly
Where does the lacunar ligament insert?
Pectineal line (superior pubic ramus) at pectineal ligament
What does the free edge of the lacunar ligament form?
Medial margin of femoral ring
How are the weak areas of the inguinal canal reinforced?
Oblique course
Compressed by internal oblique and transversus abdominis
Squatting (defaecation/childbirth) - Thighs protect wall
What is an indirect inguinal hernia?
Protrusion of tissue via deep inguinal ring
What is a direct inguinal hernia?
Protrusion of tissue by pushing through posterior wall into inguinal canal