Intercostal Space

Question 1

ICS: what is it + what does it consist of?

Answer 1

Space btw. 2 ribs
IC muscles = external, internal + innermost
Neurovascular plane
11 ICS with bundles

Question 2

External IC muscles

Answer 2

Downwards + med.
Tubercles to costochondral junction
External IC membrane
Inf. margin above to sup. margin below
Ext. oblique
Primary + forced inspiration

Question 3

Internal IC muscles

Answer 3

Downwards + post.
Opposite direction
Floor of groove to sup. margin
Attach as far as sternum + angle of ribs
Internal IC membrane
Int. oblique 
Weaker
Secondary expiration

Question 4

Innermost IC muscles

Answer 4

Downwards + post.
Similar to internal
Separated by IC bundle
Btw. inner surfaces of ribs
Elevate next rib
Innervated by IC n.

Question 5

Neurovascular plane

Answer 5

Btw. internal + innermost
Costal groove
VAN
Collateral bundle = sup. to rib - damage in drain

Question 6

Atypical IC nerves

Answer 6

Originate T1-T12
T1-T6 - sternum
T7-T12 = thoracoabdominal
Collateral, lat., ant. + muscular branches

Question 7

Typical IC nerves

Answer 7

T3-T6
Run within ICS
Lat. + ant. cutaneous branches

Question 8

Atypical IC nerves: origin + innervation

Answer 8

T1 = brachial plexus
T2-(3) = intercostobrachial n.
T5-9 = greater splanchnic - foregut
T7-11 = lesser splanchnic - midgut
T12 = least splanchnic - hindgut

Question 9

Blood supply of thoracic wall: name

Answer 9

Ant. IC a.

Post. IC a.

Question 10

Anterior IC arteries

Answer 10

ICS 1-6 = lat. br. of ITA
ICS 7-9/10 = musculophrenic a.
ICS 10-11 = no ant. IC a.

Question 11

Posterior IC arteries

Answer 11

ICS 1-2 = supreme IC a. = from subclavian
ICS 3-11 = br. of descending aorta
Below ICS 12 = subcostal a. (aorta)

Question 12

ITA: supply, course + branches

Answer 12

Ant. thoracic wall - clavicle to umbilicus

Course:

• Br. of SCA in neck
• crosses phrenic on right, lat. on left
• enters thorax, post. 1st cartilage
• lat. to sternum, post. 2nd-6th cartilages
• 6th - terminal branches
• sup. epigastric - diaphragm
• musculophrenic post. 7th-10th - towards diaphragm + gives ant. IC branches to ICS 7-10
• at inlet - pericardiophrenic follows phrenic, supplies diaphragm, pericardium + pleura

Question 13

Thoracic wall: anastomoses

Answer 13

External iliac + sublavian:

• EI = inf. epigastric
• SCA = ITA = sup. epigastric
• inf. + sup. anastomose

Descending aorta + subclavian artery:

• SCA = ITA = ant. IC a.
• aorta = post. IC a.
• ant. + post. anastomose

Question 14

Venous drainage of thoracic wall: anterior, posterior left + posterior right

Answer 14

Anterior:
*ITV, brachiocephalic

Posterior left:

• 1 = brachiocephalic
• 2-4 = sup. left IC, brachiocephalic
• 5-8 = acc. hemiazygous
• 9-12 = hemiazygous

Posterior right:

• 1 = brachiocephalic
• 2-3(4) = sup. right IC, azygous
• 4-12 = azygous