Anterior Abdominal Wall Flashcards
What are the layers of the anterior abdominal wall?
Skin, fatty layer of superficial fascia (Camper’s fascia), membranous layer of superficial fascia (Scarpa’s fascia), external oblique, internal oblique, transversus abdominus, fascia transversalis, extra peritoneal fat, parietal peritoneum
What direction are the fibres of external oblique?
Anteroinferior (hands in front pockets)
What is the upper origins of the external oblique muscle?
Overlaps the costal margin and extends onto the front of the lower 8 ribs - lies edge to edge with pec major and serratus anterior
What is the lower insertion of the external oblique muscle?
Anterior half of the iliac crest, ASIS, pubic tubercle and pubic crest
What are the 3 free edges of the external oblique muscle?
superior aponeurotic edge (where pec major starts), free posterior muscle edge, free inferior edge (inguinal ligament)
What direction are the fibres of internal oblique?
Posteroinferior (hands in back pockets)
What is the upper origin of the internal oblique muscle?
The costal margin
What is the lower insertion of the internal oblique muscle?
Anterior 2/3rds of the iliac crest and the lateral 2/3rds of the inguinal ligament and the pubic crest (insert as the conjoined tendon)
What is the posterior origin of the internal oblique muscle?
Thoracolumbar fascia
What direction are the fibres of transverses abdominus?
Horizontal
What is the upper origin of the transversus abdominus?
The diaphragm - it is in one continuous muscle plane
What is the lower insertion of the transversus abdominus muscle?
Anterior 2/3rds of the iliac crest and the lateral 1/2 of the inguinal ligament and the pubic crest (insert as the conjoined tendon)
What is the posterior origin of the transversus abdominus?
thoracolumbar fascia
What direction are the fibres of rectus abdominus?
Vertical
What is the upper origin of rectus abdominus?
Costal cartilage 5,6 and 7
What is the lower insertion of rectus abdominus?
Body and crest of the pubis
What is the lateral border of rectus abdominus?
Linea semilunaris
What is the medial border of rectus abdominus?
Linea alba
Where are the tendinous intersections of rectus abdominus?
The umbilicus, the xiphy sternum and half way in between
What is the surface marking for the gall bladder?
Where linea semilunaris intersects with the costal margin
What is the rectus sheath?
An aponeurotic envelope that contains rectus abdominus - formed by the aponeusosi of the 3 muscles of the anterior abdominal wall
What makes up the anterior part of the rectus sheath above the arcuate line?
aponeurosis of external oblique and half of internal oblique
What makes up the posterior part of the rectus sheath above the arcuate line?
half of the aponeurosis of internal oblique and the aponeurosis of transversus abdominus
What makes up the anterior part of the rectus sheath below the arcuate line?
The aponeurosis of external oblique, internal oblique and transversus abdominus
What makes up the posterior part of the rectus sheath below the arcuate line?
There is no posterior part of the rectus sheath below the arcuate line
Where is the neurovascular plane of the anterior abdominal wall?
Between internal oblique and transversus abdominus
Which spinal segment is the dermatome for the umbilicus?
T10
Which spinal segment is the dermatome for the groin?
L1
What is the blood supply of the anterior abdominal wall?
superior epigastric (branch of internal thoracic) and inferior epigastric (branch of external iliac)
What is the venous drainage of the anterior abdominal wall?
Dual drainage - portal and systemic - site of portosystemic overlap
What is the inguinal region?
The transition zone between the lower abdomen and upper thigh
What is the inguinal ligament?
The inferior edge of the external oblique muscle
What is the lacunar ligament?
The aponeurosis of the external oblique that is reflected against the pectineal line of the pubis
What is the pectineal ligament?
The extension of the lacunar ligament
Where do the testes develop?
In the posterior abdominal wall in the extra peritoneal fat
How do the testes get to the scrotum?
Via the inguinal canal
Where are the testes at in the 12th week of development?
The pelvis
Where are the testes at in the 28th week of development?
The deep ring
How long does it take for the testes to traverse the inguinal canal?
3 days
How long is the inguinal canal?
4cm
What is the opening of the inguinal canal?
The deep inguinal ring - a deficiency in the fascia transversalis half way between the ASIS and pubic tubercle a fingers breadth above the inguinal ligament
What is the exit of the inguinal canal?
The external inguinal ring - a triangular opening in external oblique between the pubic tubercle and pubic crest
What is the roof of the inguinal canal?
Arching fibres of internal oblique and transversus abdominus
What is the floor of the inguinal canal?
The inguinal ligament
What is the anterior wall of the inguinal canal?
external oblique aponeurosis and the internal oblique muscle (laterally)
What is the posterior wall of the inguinal canal?
transversalis fascia and the conjoint tendon (medially)
What is the spermatic cord?
The vas deferens and neurovascular structures surrounded by 3 layers of covering
What is the 1st layer of covering of the spermatic cord?
Internal spermatic fascia - from the fascia transversalis
What is the 2nd layer of covering of the spermatic cord?
Cremasteric fascia and cremaster muscle - from internal oblique
What is the 3rd layer of covering of the spermatic cord?
External spermatic fascia - from external oblique
What are the common sites of abdominal wall hernias?
umbilicus, linea alba, linea semilunaris, incisional, inguinal
What is an indirect inguinal hernia?
Where the abdominal contents traverse the inguinal canal and go into the scrotum
Why does an indirect inguinal hernia occur?
Incomplete closure of the processes vaginalis
What is a direct inguinal hernia?
A protrusion directly forwards into the inguinal canal through a weakness in its posterior wall - abdominal contents don’t go into the scrotum
Why are you predisposed to an indirect inguinal hernia post appendectomy?
Because L1 fibres are cut