Thorax Muscles

Question 1

External Intercostal Muscles:

Answer 1

• Fibers running down and forward
• Inspiration

Question 2

Internal & Innermost Intercostal Muscles:

Answer 2

• Fibers run down and backwards
• Expiration

Question 3

Diaphragm:

Answer 3

Origin:
- Inferior thoracic aperture

Insertion:
- Central tendon

Function:
- Inspiration

Question 4

Serratus Anterior:

Answer 4

Medial Attachment:
- Lateral surface of ribs 1-9

Lateral Attachment:
- Medial border of scapula

Function:
- Protraction of Scapula

Question 5

Pectoralis Major:

Answer 5

Origin:
- Medial Clavicle
- Sternum
- Ribs 1-7

Insertion:
- Bicipital groove of humerus

Function:
- Flexion, adduction, and medial rotation of the arm

Question 6

Pectoralis Minor:

Answer 6

Origin:
- Ribs 2-5

Insertion:
- Coracoid Process of scapula

Function:
- Weak shoulder protraction (serratus anterior is prime mover)