Serratus Posterior Muscles

Question 1

Serratus Posterior Superior

Answer 1

O: ligamentum nuchae + spinous processes of C7 - T2 or T3

I: upper ribs (usually ribs 2-5)

A: elevation of ribs

In: ventral rami of upper 3-4 thoracic spinal nerves

Question 2

Serratus Posterior Inferior

Answer 2

O: spinous processes of T11 - L2

I: lower 3-4 ribs

A: pulls lower ribs inferiorly

In: ventral rami of lower thoracic (9th-12th) spinal nerves

Question 3

Levator Costarum

Answer 3

Action: Assists with deep inspiration (inhalation)

Innervation: dorsal rami

Question 4

Transverse Thoracis

Answer 4

Insertion: underside of sternum

Action: active in forceful expiration (exhalation)