muscles of posterior abdominal wall

Question 1

Answer 1

psoas major

• *Superior attachments** : transverse processes of lumbar vertebrae; sides of bodies of T12-S1 vertebrae and intervening IV discs
• *Inferior attachments** : By a strong tendon to lesser trochanter of femur

Action : acting inferiorly with illiacus, flexes thigh ; acting superiorly, flexes vertebral column laterally to balance the trunk; when sitting acts inferiorly with illiacus to flex trunk

Innervation: Lumbar plexus via anterior branches of nerves L2-L4

Question 2

Answer 2

Illiacus

Superior attachment : superior two thirds of iliac fossa, ala of sacrum, and anterior sacro-iliac ligaments

inferior attachments : lesser trochanter of femur and shaft inferior to it and to psoas major tendon

action : flexes thigh and hip and stabilizes hip joint; acts with psoas major

innervation: femoral nerve L2-L4

Question 3

Answer 3

quadratus lumborum

Superior attachment : medial half of inferior border of 12th rib and lumbar transverse processes

inferior attachments : iliolumbar ligament and iliac crest

action : extends and laterally flexes vertebral column, stabilizes lower back; fixes 12th rib during inspiration

innervation: anterior branches of T12 and L1-L4 nerves

Question 4

Answer 4

Psoas minor

-lies on top of major

superior attachment : side of T12 and L1 vertebra and intervertebral discs

Inferior attachment: halfway through becomes a tendon and attaches onto Inguinal ligament and rim of pelvis

action: weak trunk flexor

innervation: anterior ramus of L1

Question 5

Diaphragm

Question 6

Diaphragmatic crura

Answer 6

• tendinous structure which extends from diaphragm to vertibral column
• Crus= leg (leg shaped appearance)
• right and left which help with muscular contraction

Question 7

femur

Answer 7

Linea aspera : ridge on the posterior aspect of femur, lots of medial thigh muscles attach to

Adductor muscles, pectineus, biceps femoris, vastus lateralis and medialis

Pectineal line : pectinous muscle attaches to

Greater Trochanter attachment for 5 muscles : gluteus medius, gluteus minimus, piriformis, obturator externus, obturator internus

Lesser trochanter : attachment to tendon of psoas major and illiacus