Muscles Of The Thoracic Wall

Question 1

Serratus posterior superior

Origin
Insertion
Innervation
Movement

Answer 1

Origin :

• nuchal ligament
• spinous processes of C7-T3 vertebrae

Insertion:

• superior borders of 2nd to 4th rib.

Innervation:

2nd to 5th intercostal nerves

Movement : proprioception (elevates the Ribs)

Question 2

Serratus posterior inferior

Origin
Insertion
Innervation
Movement

Answer 2

Origin
- spinous processes of T11 to L3 vertebrae.

Insertion
- inferior borders of 8th to 12th ribs near their costal angle.

Innervation
- anterior rami to T9 to T12 thoracic spinal nerves

Movement
Proprioception (depresses ribs)

Question 3

Levator costarum

Origin
Insertion
Innervation
Movement

Answer 3

Origin
- transverse processes of C7-T11 vertebrae.

Insertion
- between tubercle and costal angle of the subjacent rib.

Innervation
- posterior primary rami of C8-T11 nerves

Movement
- elevation of ribs

Question 4

External intercostal

Attachments
Innervation
Movement

Answer 4

Attachment

• inferior border of rib above
• superior border of rib below

Innervation
- intercostal nerve

Movement
- elevated ribs during forced inspiration

Question 5

Internal intercostal muscle

Answer 5

Attachments

• inferior border of rib above
• superior border of rib below

Innervation
- intercostal nerve

Movement 
- interosseous part , depresses ribs 
- interchondrial part, elevates ribs 
During active (forced) respiration

Question 6

Innermost intercostal muscle

Answer 6

Attachments

• inferior border of rib above
• superior border of rib below

Innervation
- intercostal nerve

Movement 
- interosseous part , depresses ribs 
- interchondrial part, elevates ribs 
During active (forced) respiration

Question 7

Transverse thoracis

Answer 7

Attachment

• posterior surface of lower sternum
• internal surface of costal cartilages 2-6.

Innervation
- intercostal nerve

Movement
- Weakly depresses ribs

Question 8

Subcostal

Answer 8

Attachments

• internal surface of lower ribs near their angles.
• superior borders of 2nd or 3rd ribs below.

Innervation
- intercostal nerve

Action

• interosseous part depresses ribs.
• interchondral part elevates ribs