Abdomen

Question 1

External oblique

Answer 1

Origin : external surfaces of 5th-12th ribs
Insertion : linea alba, public tubercle, and anterior half of iliac crest
Innervation : thoraco-abdominal nerves (anterior rami of T7-T11) and subcostal nerve
Action : compress and support abdominal viscera
flex and rotate trunk

Question 2

Internal oblique

Answer 2

Origin : thoracolumbar fasciae, anterior two thirds of iliac crest, and connective tissue deep in inguinal ligament
Insertion : inferior borders of 10th-12th rib, linea alba, and pubis via conjoint tendon
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11), subcostal and first lumbar nerve
Action : compresses and supports viscera
flex and rotate trunk

Question 3

Transverse abdominis

Answer 3

Origin : internal surface of 7th-12th costal cartilages, thoracolumbar fasciae, iliac crest, connective tissue deep to inguinal ligament
Insertion : linea Alba with aponeurosis of internal oblique, pubic crest, and pubis via conjoint tendon
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11), subcostal and first lumbar nerve
Action : compresses and supports abdominal viscera

Question 4

Rectus abdominis

Answer 4

Origin : pubic symphysis and pubic crest
Insertion : xiphoid process and 5-7th costal cartilages
Innervation: thoraco-abdominal and subcostal nerves (anterior rami of T7-T12 spinal nerves)
Action : flexes trunk (lumbar vertebrae), and compresses abdominal viscera, stabilizes and controls tilt of pelvis (antilordosis)

Question 5

Psoas major

Answer 5

Origin : transverse process of lumbar vertebrae; sides of bodies of T12-S1 vertebrae and intervening IV discs
Insertion : strong tendon to lesser trochanter or femur
Innervation : lumbar plexus via anterior branches of nerves L2-L4
Action : acting inferiorly with iliacus, flexes thigh
acting superiorly, flexes vertebral column laterally to balance
the trunk
when sitting, act inferiorly with iliacus to flex trunk

Question 6

Iliacus

Answer 6

Origin : superior two thirds of iliac fossa, ala of sacrum, anterior sacro-iliac ligaments
Insertion : lesser trochanter of femur and shaft inferior to it and to psoas of major tendon
Innervation: femoral nerve (L2-L4)
Action : flexes thigh and stabilizes hip joint
act with psoas major

Question 7

Quadratus lumborum

Answer 7

Origin : medical half of inferior border of 12th rib and tips of lumbar transverse processes
Insertion : iliolumbar ligament and internal lip of iliac crest
Innervation: anterior branches of T-2 and L1-L4
Action : extends and laterally flexes vertebral column
flexes 12th rib during inspiration

Question 8

Diaphragm

Answer 8

Origin : xiphoid process; inner surface of 7th-12th rib, anterior surfaces of L1-L3, fasciae over quadratus lumborum, psoas major muscles via medial and lateral arcuate ligaments
Insertion - central tendon of diaphragm
Innervation : phrenic nerve C3-C5
Action : contracts to increase intrathoracic volume during inhalation and pushes abdominal viscera inferiorly