Trunk Muscles

Question 1

Lumbar Muscles of the Trunk

Answer 1

Psoas Major
Psoas Minor
Illiacus
Quadratus Lumborum

Question 2

Psoas Major

Answer 2

origin from the bodies and transverse processes of the L1-L5 and then T12

inserts onto the lesser trochanter of the femur

Question 3

Psoas Minor

Answer 3

origin at L-1

attaches to the lesser trochanter of the thigh

Question 4

Illiacus

Answer 4

origin at the crest of the ilium

attaches to the lessor trochanter

action: flexion of the hip joint and tilting of the pelvis

Question 5

Quadratus Lumborum

Answer 5

origin from the posterior iliac crest

inserts on the 12th rib and transverse process of L1-L5

action: lateral flexion of the lumbar spine and rib cage when pelvis is fixed
- if ribs are fixed it raises the pelvis
- unilateral contraction it raises one side of the pelvis

Question 6

Anterior Muscles of the Trunk

Answer 6

Transversus Abdominus
Internal Oblique
External Oblique
Rectus Abdominus

Question 7

Transversus Abdominus

Answer 7

origin at the inner surfaces of the 7th-12th ribs

attaches below at the 3rd lateral of the inguinal ligament and the iliac crest

Question 8

Internal Oblique

Answer 8

origin above lower ribs anteriorly to a tendon

attaches below to the lateral half of the inguinal ligament and the lilac crest

action: unilateral contraction produces a side bending or lateral contraction of spine and rib cage
- ipsilateral rotation of the spine and rib cage
- bilateral contraction produces a compression of the abdomen it also assists in flexion of the funk

Question 9

External Oblique

Answer 9

external muscle which attaches to the outer surfaces of 5th-12th ribs

Question 10

Rectus Abdominus

Answer 10

formed by the aponeurouses of the 3 other abdominal muscles

runs from the crest and symphysis off the pubis to the typhoid process and to the cartilages of the 5th-7th ribs

action: flexion of the trunk
compression of abdominal wall