Thoracic Walls

Question 1

Pectoralis Major

Origin

Insertion

Answer 1

Origin:

• Clavicular head- ant. medial clavicle
• Sternocostal head- sternum and first 7 costal cartilages

Insertion:

• Lateral lip/ridge of bicipital groove

Question 2

Pectoralis Major

Action

Innervation

Answer 2

Action:

• Clavicular head: arm flexion
• Sternocostal head: arm extension
• Both heads: adduction, medial rotation of arm at glenohumeral joint

Innervation:

• Medial (C8, T1) and lateral pectoral n.(C5-7)

Question 3

Pectoralis Minor

Origin

Insertion

Answer 3

Origin:

• Ribs 3-5

Insertion:

• Coracoid process of scapula

Question 4

Pectoralis Minor

Action

Innervation

Answer 4

Action:

• Pulls tip of shoulder down
• Protracts scapula

Innervation:

• Medial pectoral n.

Question 5

Subclavius

Origin

Insertion

Answer 5

Origin:

• 1st rib- between rib and costal cartilage

Insertion:

• Subclavian groove (inf. middle clavicle)

Question 6

Subclavius

Action

Innervation

Answer 6

Action:

• Pulls tip of shoulder down
• Pulls clavicle medially to stabilise sternoclavicular joint

Innervation:

• Nerve to subclavius (C5, C6)

Question 7

Serratus Anterior

Origin

Insertion

Answer 7

Origin:

• Lateral surfaces of ribs 1-8

Insertion:

• Ant. medial scapula

Question 8

Serratus Anterior

Action

Innervation

Answer 8

Action:

• Protracts and rotates scapula
• Stabilises scapula by holding it to chest wall

Innervation:

• Long thoracic n. (C5, C6, C7)