Intercostal spaces

Question 1

What are the intercostal spaces and what lies in the intercostal groove?

Answer 1

Intercostal spaces are the spaces between the ribs. Lying in the subcostal groove of the rib, is the neurovascular bundle (~VAN)

• Intercostal vein (top)
• Intercostal artery
• Intercostal nerve (bottom)

Question 2

What is the origin, insertion, innervation of the external intercostal muscles?

Answer 2

(fibres downwards~ hands in pocket)

T1-T11 intercostal nerves

Move ribs superiorly and cause inspiration

Question 3

What is the origin, insertion, innervation and function of internal intercostal muscles?

Answer 3

(fibres move upwards~hands on tits)

T1-T11 intercostal nerves

Move ribs inferiorly and cause expiration

Question 4

What is the origin, insertion, innervation and function of innermost intercostal muscles?

Answer 4

T1-T11 intercostal nerves

Aid internal intercostal

Question 5

What is the origin, insertion, innervation and function of subcostalis?

Answer 5

intercostal nerves and depress ribs

Question 6

What is the origin, insertion, innervation and function of transversus thoracis?

Answer 6

• originate from costal cartilage II-VI
• insert into body of sternum and xiphisternum
• intercostal nerves and depress the costal cartilage

Question 7

Describe the arterial supply of the intercostal arteries and what do they terminate as?

Answer 7

Intercostal spaces are supplied by the intercostal arteries.

• Anterior intercostal arteries-from the internal thoracic artery from subclavian
• Posterior intercostal arteries

First 1-2

-from supreme intercostal artery from costocervical trunk of subclavian artery

Last 9

-from descending thoracic aorta

At the level of ICS 6, anterior intercostal arteries bifurcate into:

• Musculophrenic artery-pierces diaphragm
• Superior epigastric artery-runs along anterior abdominal wall

Question 8

Describe the venous drainage of intercostal veins?

Answer 8

Intercostal spaces drain into intercostal veins

• Anterior intercostal veins-drain into internal thoracic vein
• Posterior intercostal veins-right drains into right superior intercostal vein that drains into azygos vein; left drains into left superior intercostal vein that drains into lt brachiocephalic vein

Question 9

Describe the lymph drainage of intercostal spaces?

Answer 9

They are drained by these lymph nodes

• Parasternal lymph nodes
• Diaphragmatic lymph nodes (behind xiphisternum)
• Intercostal lymph nodes

Question 10

Describe the innervation of intercostal spaces?

Answer 10

They are innervated by intercostal nerves from anterior rami of T1-T11 spinal nerves. (T12 forms subcostal nerve underneath rib 12) These form the lateral cutaneous branches which splits into anterior and posterior branches.

These terminate as anterior cutaneous branches that pierce skin.

Altogether they provide:

• Sensory to skin
• Motor to muscles of thoracic cage