Abdomen I: Abdominal Wall and Inguinal Canal Flashcards
Abdominal Landmarks
Surface Anatomy
Right Illiac Region - Appendix
Left Lumbar Region - Descending Colon, spleen, left kidney
Left Hypochondriac Region - Stomach, Spleen, some of the liver, Pancreas
Semi Lunaris - Lateral border of Rectus Abdominus
Position of Transpyloric Plane
L1 - Pylorus*
Position Of Subcostal Plane
L2
Position Of Transtubecular Plane
L4/L5 - tubercles of iliac crest
Surface Anatomy 2 (which planes are the arrows pointing to?)
Lateral muscles made up of three muscles:
1- External Oblique
2 - Internal Oblique
3- Tranverse Abdominis
Superficial Facia becomes two distinct layers
Camper’s Fascia
Scarpa’s Fascia
Camper’s Fascia
- Fatty
Continuous with:
- Superficial fascia of thigh
- Superficial fascia of penis
- Dartos Fascia ♂
- Perineum and labia majora ♀
Scarpa’s Fascias
- Membranous
Continuous with:
- Superficial fascia of thigh
- Superficial fascia of penis
- Dartos Fascia ♂
- Perineum and labia majora ♀
Extravasation of Urine
Rupture of urethra leading to collection of urine and blood in superficial perineal space, scrotum and potentially lower anterior abdominal wall.
Muscles of Anterior Wall
External Oblique Muscle
- Outmost layer.
- Inferomedial fibre direction (hands in pockets)
- Becomes Aponeurosis medially: Anterior border of rectus sheath.
- Inferior border of external oblique is the Inguinal Ligament
- (It stretches from the anterior superior iliac spine (ASIS) to the pubic tubercle (PT))
Origin:
Insertion:
Nerve supply:
Function:
External Oblique Muscle
- Origin: External surfaces of 5 – 12th ribs
- Insertion: Linea alba, pubic tubercle, ant. half of iliac crest
- Nerve supply: Thoracoabdominal nerves (T7- T11) and subcostal nerve (T12)
- Function: Compresses and supports abdominal viscera; flex and rotate trunk
Internal Oblique Muscle
- Absolutely perpindicular to external oblique
- Intermediate layer
- Superomedial fibre direction.
- Medial aponeurosis*
Origin:
Insertion:
Nerve supply:
Function:
Internal Oblique Muscle
- Origin: Thoracolumbar fascia, anterior 2/3rds of iliac crest and connective tissue deep to inguinal ligament
- Insertion: Inferior border of 10th-12th ribs, linea alba and pubis via conjoint tendon
- Nerve supply: Thoracoabdominal (T7 - T11), subcostal (T12), iliohypogastric (L1) and ilioinguinal (L1)
- Function: compresses and supports abdominal viscera; flex and rotates trunk
Transversus Abdominis Muscle
- Innermost muscle layer.
- Transverse fibre direction.
- Medial aponeurosis: Posterior layer of rectus sheath.
- Neurovascular plane between internal oblique and rectus abdominis.
She mentions how the arterial and nerve structures go through this area between external & internal obliques
Origin:
Insertion:
Nerve supply:
Function:
Transversus Abdominis Muscle
- Origin: Internal surface of 7th – 12th costal cartilages (CC), thoracolumbar fascia, iliac crest and connective tissue deep to lat. 1/3rd inguinal ligament
- Insertion: Linea alba, pubic crest and pectin pubis via conjoint tendon
- Nerve supply: Thoracoabdominal (T7-T11), Subcostal (T12), iliohypogastric (L1) and ilioinguinal (L1)
- Actions: compresses and supports abdominal viscera * antagonistic to diaphragm
Layers of the (lateral) Abdominal Wall - Summary
Rectus Abdominis Muscle
- Paired strap muscle separated by linea alba (white line).
- Three of more tendinous intersections.
- Lateral border forms linea semilunaris.
- Origin:
- Insertion:
- Nerve supply:
- Action:
Rectus Abdominis Muscle
- Origin: Pubic symphysis and pubic crest.
- Insertion: Xiphoid process and 5th - 7th costal cartilages.
- Nerve supply: Thoracic abdominal nerves (T7-T11) and subcostal nerve (T12).
- Action: Flexion of trunk, compresses abdominal viscera and controls tilt of pelvis.
Pyramidalis Muscle
- Absent in approximately 20% people.
- Landmark for median abdominal incisions.
- Origin:
- Insertion:
- Nerve supply:
- Action:
Pyramidalis Muscle
- Origin: Pubic crest
- Insertion: Linea alba
- Nerve Supply: Subcostal nerve (T12)
- Action: Tense linea alba
Rectus Sheath is the…
…Aponeuroses of External Oblique, Internal Oblique, Transversus Abdominis
Fibrous compartment enveloping:
- Rectus abdominis
- Pyramidalis
- Superior and inferior epigastric vessels
- Distal portions of thoracoabdominal nerves
- Corresponding lymphatics
Linea Alba is the…
…Interlacing fibres of anterolateral muscles (formed when left and right Aponeuroses come together and fibres cross over - thickening)
Important thing: Doesn’t have blood supply (ideal for Median surgical incision)
- Collagen: white line
- Xiphoid process to pubic crest
- Umbilicus lies in midline
Superior to arcuate line Rectus Sheath