Neck / Trunk Muscles

Question 1

Latissimus Dorsi

Answer 1

O: spinous processes of T7-T12, spinous processes of L1-L5 via thoracolumbar fascia, ninth to twelfth ribs, iliac crest
I: floor of intertubercular sulcus of humerus
A: shoulder adduction, medial rotation, extension (GHJ)

Question 2

External obliques

Answer 2

O: external surfaces and inferior borders of 5-12th ribs
I: ASIS, anterior half of iliac crest, pubic crest, pubic tubercle, linea alba
A: trunk flexion, lateral flexion, rotation; compresses and provides structural support to adjacent abdominal structures

Question 3

Internal oblique

Answer 3

O: thoracolumbar fascia, iliac crest, inguinal ligament
I: inferior margins of 10-12th ribs and adjacent costal cartilages, linea alba, pecten pubis
A: trunk flexion, lateral flexion, rotation; compresses and provides structural support to adjacent abdominal structures

Question 4

Quadratus lumborum

Answer 4

O: posterior 1/2 of iliac crest and iliolumbar ligament
I: inferior border of 12th rib, transverse processes of 1-4th lumbar vertebrae
A: trunk extension, lateral flexion; stabilizes 12th rib during inspiration

Question 5

Quadratus lumborum

Answer 5

O: posterior 1/2 of iliac crest and iliolumbar ligament
I: inferior border of 12th rib, transverse processes of 1-4th lumbar vertebrae
A: trunk extension, lateral flexion; stabilizes 12th rib during inspiration