Lecture 14 Posterior abdominal wall Flashcards
What is the partition between the abdominal cavity and pelvic cavity?
- There is no physical barrier between the two cavities
What is the barrier between thorax and abdomen?
- diaphragm
What protects some of the upper abdominal organs?
- the ribs and costal cartilages of the rib cage
What forms the upper margin of the hip bone?
- the iliac crest
What ligament stretches between the iliac spine and pubic tubercle?
- inguinal ligament
How does the diaphragm lie in the posterior abdominal wall?
- vertical
Where is the origin of the quadratus lumborum?
the iliac crest
what is the function of quadratus lumborum?
- pulls down on 12th rib
- bilateral function- weak extensor of trunk
- unilateral function - lateral flexion of trunk
- active in walking and stabilizes trunk and maintains balance
What is the function of psoas major?
- hip flexor
- can also act as flexor of the spine
Where does psoas minor originate?
- lumbar/ T12 spines
Where is the insertion of psoas minor?
- pubic bone
What is the function of psoas minor?
- thought be a proprioceptive muscle
- movement function is not significant
- it is also variable present and you wont miss it much
What innervates the quadratus lumborum?
- ventral rami of T12-L4
What innervates psoas major/minor
- ventral rami of L1-3
What innervates the iliacus?
- femoral nerve
What is the origin of the iliacus?
- iliac fossa fuses with psoas major common insertion to femur
What is the function of the iliacus?
- assist in thigh flexion
Where does iliacus attach to vertebrae?
- it doesn’t
- onlu attaches to iliac crest and fossa so no role in flexion of spine
Where is the insertion of quadratus lumborum?
- T12
Where does illacus insert?
- lesser trocantor
Why do we have thick heavy layers of quadratus lumborum fascia?
- because it serves as a point of origin for the diaphragm where no bone is available
Where does the lateral arcuate ligament originate?
- quadratus lumborum fascia
Where does the medial arcuate ligament originate from?
- psoas major fascia
what is the function of the lateral arcuate ligament?
- point of origin for diaphragm
median arcuate ligament
- outlines aortic hiatus (where aorta goes from thoracic to abdominal)
- between curu of diaphragm
Where does the L1 ventral ramus pass?
- behind the psoas major muscle
What is the vertebrae associated with the subcostal nerve?
- T12
What is the vertebrae associated with the iliohypogastric nerve?
- L1
What is the vertebrae associated with the ilioinguinal nerve?
- L1
What is the vertebrae associated with the genitofermoral nerve?
- L1-2
What is the vertebrae associated with the lateral femoral cutaneous nerve?
- L2-3
What is the vertebrae associated with the femoral nerve?
- L2-4
What is the vertebrae associated with the obturator nerve?
- L2-4
What is the vertebrae associated with the lumbosacral trunk?
- L4-5
What nerves does the L1 ventral ramus give rise to?
- iliohypogastric n. (superior)
- ilioinguinal nerve ( genetalia skin)
What nerve pierces the psoas major?
- the genitofemoral nerve (only sensory in females)
- in males it is motor and sensory (males have cremaster muscle)
What nerve crosses over the ilacus?
- lateral femoral cutaneous nerve
Lateral femoral cutaneous nerve
- sensory only in both sexes
- can be compressed during pregnancy or obese patients
- passes through narrow angle between bone and tendon (inguinal ligament and anterior iliac spine)
Largest branch of the lumbar plexus?
- femoral nerve (combines branches from L2, L3, L4)
Femoral nerve supplies
- anterior muscle of thigh
- skin over that muscle
- motions of flexion of hip and extension of knee
What function does the obturator carry out?
- adduction of hip (supplies medial inner thigh muscles)
What does lumbosacral trunk do?
- travels down to pelvis to contribute to the sciatic nerve
Sympathetic trunk
- paravetebral ganglia
- post-ganglionic sympathetics (supply skin)
What nerves does the lumbar plexus carry?
- somatic motor
- somatic sensory
- sympathetics to visceral body wall (sweat glands)
What is the lumbar plexus?
- a set of nerves made of the ventral rami of the T12 through L5 spinal nerves.
Why is the lumbar plexus neccessary?
- the large limbs need to be more complex than the simple strips of muscles derived from single myotomes
- The limb muscles are derived from multiple myotomes so they require innervation from the corresponding multiple spinal nerves. It is more efficient to combine the axons supplying large muscles into large nerves
Where does the L1 ventral ramus nerve pass?
- behind the psoas major
