Abdominal wall & Development Flashcards
(15 cards)
What are the three basic layers of the abdominal wall?
Skin, subcutaneous fascia and muscles
What four muscles comprise the abdominal wall?
Lateral (from outside to inside): external abdominal oblique, internal abdominal oblique, transverse abdominal
Ventrally: rectus abdominis (six pack)
Define the functions of the abdominal wall muscles.
- Encloses the abdominal cavity and its content
- Motor functions e.g. contraction causes increase in intra-abdominal pressure (used in vomiting)
What separates the left and right rectus abdominis muscle?
Linea alba
Describe the external oblique muscles.
- Outermost lateral abdominal wall muscle
- Originates on lateral caudal surfaces of ribs 4+ and lumbodorsal fascia
- Inserts on linea alba and prepubic tendon
- Fibres run obliquely from cranio-dorsal to caudo-ventral
Describe the internal oblique muscles.
- Middle lateral abdominal wall muscle
- Originates on coxal tuber and lumbodorsal fascia
- Inserts on linea alba, last rib & cartilages of caudal ribs
- Fibres run obliquely from caudo-dorsal to cranio-ventral
Describe the transverse abdominal muscle.
- Innermost lateral abdominal wall muscle
- Originates on medial surfaces of ventral parts of caudal ribs and deep lumbodorsal fascia
- Inserts on linea alba
- Fibres run transversely
Describe the sheath of rectus abdominis muscle.
- Formed from the tendons of the lateral abdominal wall muscles
- They pass above / below rectus abdominis m. to join in the midline
- This join is referred to as an ‘aponeurosis’ and forms the linea alba
Describe the innervation of the abdominal wall.
- Innervated by spinal nerves of last thoracic vertebra & L1-L5
- Dorsal roots innervate dorsal musculature
- Ventral roots split into 3 branches
Medial - Runs between TA & IAO down to RA
Lateral - Runs between IAO & EAO down to midway
Lateral cutaneous - Perforates EAO to innervate skin
What is the inguinal canal?
- Internal oblique muscle has gap
- External oblique muscle has slit
- It is the potential space between these 2 slits
Where do the abdominal organs develop from and what is this divided into?
Embryological gut tube - foregut, midgut and hindgut.
What 3 arteries supply the divisions of the embryological gut tube?
Foregut - celiac trunk
Midgut - cranial mesenteric artery
Hindgut - caudal mesenteric artery
What does the foregut differentiate into?
Pharynx, oesophagus, stomach and initial duodenum
What does the midgut differentiate into?
Rest of duodenum, jejunum, ileum, caecum, ascending / transverse colon
What does the hindgut differentiate into?
Descending colon and rectum
