Intermediate (respiratory) group of back muscles

Question 1

Serratus posterior superior

Answer 1

Origin:

• Lower portion of ligamentum nuchae
• Spinous processes of C7 to T3
• Supraspinous ligaments

Insertion:

• Upper border of ribs 2-5 just lateral to their angles

Innervation:

• Anterior rami of upper thoracic nerves

Function:

• Elevates ribs 2-5

Question 2

Serratus posterior inferior

Answer 2

Origin:

• Spinous processes of T11 to L3 and supraspinous ligaments

Insertion:

• Lower border of ribs 9 to 12 just lateral to their angles

Innervation:

• Anterior rami of lower thoracic nerves

Function:

• Depresss ribs 9 to 12 and may prevent lower ribs from beign elevated when the diaphragm contracts