Posterior Abdominal Wall

Question 1

Consists of

Answer 1

Bones
* lumbar verebrae
* Sacrum (upper margin)
* Pelvic bones (medial side of ilium)
* Ribs (11 &12): rib 12 serves as a point of attachment for muscles & ligaments

Muscles
* superiorly is the diaphragm
* medially is the psoas major and minor
* laterally is the quadratus lumborum
* inferiorly is the iliacus

Question 2

Main structures passing through the diaphragm

Answer 2

• The aorta passes posterior to the diaphragm & anterior to the vertebral bodies at the lower level of vertebra T12
• The thoracic duct (accompanying the aorta through aortic hiatus)
• The esophagus passes through the right crus at the level of vertebra T10
• The anterior & posterior vagal trunks passes w/the esophagus
• The inferior vena cava pasess from the abdominal cavity to the thoracic cavity (caval opening)
• The R phrenic nerve passes with the inferior vena cava
• The L phrenic nerve passes through the muscular part of the diaphragm just anterior to the central tendon on the left side.

Question 3

Domes of the diaphragm

Answer 3

Normal expiration places the left dome at the intercostal space 5 & the right dome at rib 5–important to remember when percussing the thorax!

During inspiration, the muscular part of the diaphragm contracts, causing the central tendon to be drawn inferiorly.
* Resulting in some flattening of the domes, enlargement of the thoracic cavity & reduction in intra-thoracic pressure.

Question 4

Blood supply

Answer 4

Superiorly
* internal thoracic –>musculophrenic & pericardiophrenic
* Thoracic aorta–> superior phrenic

Inferiorly
* Abdominal aorta–> inferior phrenic

Question 5

Innervation of diaphragm

Answer 5

• Primarily the phrenic nerves. These nerves from the C3-C5 SC levels provide all motor innervation to the diaphragm & sensory fibers to the central part
• Sensory fibers are supplied to the peripheral areas of the diaphragm by intercostal nerves