Abdominal Wall & Development Flashcards
What are the 4 layers of the abdominal wall?
Skin
Subcutaneous fascia
Deep fascia
Muscles
What is in the subcutaneous fascia? What is the thin twitch muscle within it?
Fat
Cutaneous trunki muscle
What is the deep fascia?
Tough fibroelastic sheet
How many lateral and ventral muscles are in the abdominal wall?
3 lateral (EOA, IOA, transverse abdominal) 1 Ventral (rectus abdominus)
What are the functions of the muscle in the abdominal wall?
Enclose the abdominal cavity and contents
Contract to cause an increase in pressure
Used in vomiting, defaecation, micturition, breathing, coughing, sneezing
What is the rectus abdominus commonly referred to as in humans? Where does it originate and insert?
‘6 pack’
Originates ventral surface of sternum
Inserts - cranial border of pubis via pre pubic tendon
What fibrous structures separates the left and right rectus abdominus? What pierces this?
Linea alba
Umbilicus
Where is the external abdominal oblique?
Where is it’s origin and insertion?
Outermost lateral ab wall muscle
O - lateral caudal surface of ribs& lumbodorsal fascia
I -linear alba and pre pubic tendon
What direction do the fibres of the EAO run?
Caudoventrally
What is the IAO? Where does it originate and insert?
Middle lateral ab wall muscle
O - coxal tuber and lumbodorsal fascia
I- linea alba and cartilage of caudal ribs
What direction do the fibres in the IAO run?
Cranioventrally
Where is the transverse abdominal muscle? Where does it originate and insert?
Innermost lateral ab wall muscle
Originates medial surface of caudal ribs and deep lumbodorsal fascia
Inserts linea alba
What direction do the fibres run in the transverse abdominal muscle?
Transversely
Why do fibres run in specific directions?
To allow them to slide over each other
The rectus abdominus sheath is formed by tendons in the lateral ab wall muscles. These pass to join in the midline forming what? What is this called?
Aponeurosis
Linear alba
Which nerves innervate the abdominal wall?
T13
L1-5
The dorsal roots innervate the dorsal muscles. The ventral roots split into 3 branches. What are these and where are they?
Medial (between TA and IAO)
Lateral (between IAO and EAO)
Lateral cutaneous (perforated EAO to innervate skin)
What is the deep inguinal ring?
A gap in the IAO
What is the superficial inguinal ring?
A gap in the EAO
What is the inguinal canal?
The potential space between the deep and superficial inguinal ring
What is the epithelial lining of the GI tract and associated exocrine glands called?
Endoderm
What is mesoderm?
Muscle and connective tissue found in an embryo
In GI embryology, what does the foregut differentiate to form?
Pharynx, oesophagus, stomach and some of the duodenum
What does the midgut differentiate to form in GI embryology?
Rest of duodenum, jejunum, ileum, ascending and transverse colon
What does the hindgut differentiate to form in embryology?
The descending colon and rectum
What at the junction of the fore and midgut becomes the liver? (And forms pancreas)
Endodermal diverticulum
The endodermal diverticulum forms the liver at the junction of the foregut and midgut. What do the cranial branches form?
Gland tissue and hepatic ducts
The endodermal diverticulum forms the liver at the junction of the foregut and midgut. What do the caudal branches form?
Gall bladder and cystic ducts
What artery supplies the foregut?
Celiac artery
During the development of the midgut, the yolk sac reduces to form what?
Vitelline duct
When forming the midgut, it is pushed out of the abdominal cavity into the umbilicus. What is this called?Why is this?
Physiological hernia
Liver expands rapidly
What artery supplies the hindgut in embryology?
Caudal mesentric artery
