Thoracic Wall

Question 1

Intrinsic muscles, superficial to deep

Answer 1

External intercostal 
Internal intercostal
Transversus thoracis (innermost)

Question 2

External intercostal muscle, origin and insertion

Answer 2

From lower lip of rib above to outer lip of upper border of rib below

Question 3

External intercostal muscle, direction of fibres

Answer 3

Downwards, fwds and medially

Question 4

Internal intercostal muscle, origin and insertion

Answer 4

From floor of costal groove of upper rib to inner lip of upper border of rib below

Question 5

Internal intercostal muscle, direction of fibres

Answer 5

Upwards, fwds, right angle to that of external

Question 6

Parts of transversus thoracis

Answer 6

Intercostalis intimus
Subcostalis
Sternocostalis

Question 7

Intercostalis intimus, origin insertion

Answer 7

From inner surface of rib above to inner surface of rib below

Question 8

Extent of external intercostal muscle.

Answer 8

From tubercle of the rib behind to the costochondral Junction in front where it is replaced by anterior intercostal membrane

Question 9

Extent of Internal intercostal muscle.

Answer 9

From the lateral border of sternum in front to the angle of rib behind where it is replaced by the posterior intercostal membrane

Question 10

Contents of a typical intercostal space

Answer 10

• the three intercostal muscles
• intercostal veins
• intercostal arteries
• intercostal nerves
• intercostal lymph vessels and lymph nodes.

(NV bundle in intercostal space is b/w internal and innermost intercostal: in the order from above to downwards- VAN)

Question 11

Actions of intercostal muscle

Answer 11

1. Strong support of ribs, preventing their separation.

2. Elevators of ribs during respiration

Question 12

Intercostal nerve is:

Answer 12

Ventral ramii of typical spinal nerve

Question 13

Ventral primary ramus of 12th thoracic spinal nerve, running in abdominal wall is called:

Answer 13

Subcostal nerve.

Question 14

Nerve in posterior part of intercostal space

Answer 14

B/w pleura and posterior intercostal membrane

Question 15

Nerve In the remaining greater part of intercostal space

Answer 15

B/w internal intercostal muscle and intercostalis intimus

Question 16

Describe first intercostal nerve

Answer 16

Most of it joins ventral ramus C8 to form lower trunk of brachial plexus. Rest of it is very small and lacks lateral and anterior cutaneous branches

Question 17

Lateral cutaneous branch of second intercostal nerve is known as ________________

Answer 17

Intercostobrachial nerve

Question 18

Intercostobrachial nerve supplies _____________ & ______________

Answer 18

Skin of floor of axilla & upper part of medial side of arm

Question 19

Applied anatomy for intercostobrachial nerve.

Answer 19

In coronary artery disease, cardiac pain is referred along this nerve to medial side of arm

Question 20

What are thoraco-abdominal nerves

Answer 20

7th to 11th intercostal nerves. Supply muscles of corresponding intercostal space
+ muscles of anterior abdominal wall and skin, parietal peritoneum covering abdominal wall

Question 21

Root pain/girdle pain

Answer 21

Irritation of intercostal nerves due to disease of thoracic vertebrae.
Severe pain around trunk along cutaneous distribution of affected nerve

Question 22

Sites of eruption of cold abscess on body wall

Answer 22

Pus from tuberculous thoracic vertebrae (Pott's disease) 
# just lateral to sternum
# midaxillary line
# lateral to erector spinae muscle

Question 23

Herpes Zoster (shingles)

Answer 23

Cutaneous vesicles appear in dermatomal area of distribution of intercostal nerve

Question 24

Intercostal nerve block

Answer 24

Is given to produce local anesthesia in intercostal space by injecting anesthetic agent around nerve trunk, just lateral to Vertebrae.

Question 25

Conventional thoractomy

Answer 25

Posteriolateral
Along 6th rib
NV bundle protected from injury by lifting periosteum of rib

Question 26

Paracentesis thoacis

Answer 26

Aspiration of fluid from the pleural cavity. Needle should not be inserted medial to angle of rib as posterior intercostal artery passes oblique from below upwards.

Question 27

Coarctation of aorta

Answer 27

Narrowing of arch of aorta. PIA enlarged, notching of ribs, especially in posterior parts

Question 28

PIA Origin

Answer 28

1st and 2nd- superior intercostal artery, branch of costocervical trunk

3rd-11th- descending thoracic aorta

Question 29

PIA Termination

Answer 29

Anastomose with upper ant. Intercostal artery. At costochondral junction

Question 30

Collateral branch of PIA

Answer 30

Arises near angle of rib. Ends by anastomosis with lower anterior intercostal artery

Question 31

Ant. Intercostal arteries origin

Answer 31

1st-6th spaces- internal thoracic artery

7th-11th spaces- musculophrenic

Question 32

Internal thoracic artery origin

Answer 32

1st part of Subclavian artery (lower surface) about 2.5 cm above the medial end the medial end of the clavicle opposite the origin of thyrocervical trunk

Question 33

Int. Thoracic artery course

Answer 33

Behind medial end of clavicle
Upper 6 costal cartilages
1 cm away from lateral margin of sternum
At 6th space, into superior epigastric and musculophrenic arteries

Question 34

Role of internal mammary artery in treatment of coronary heart diseases

Answer 34

When the segment of coronary artery is blocked by atherosclerosis, The diseased arterial segment is bypassed by inserting a graft .
The myocardium is revascularized by mobilizing internal thoracic artery and joining its distal cut end to the coronary artery distal to diseased segment.

Question 35

IMA graft is preferred. Why?

Answer 35

Lasts long.
Less prone to developing atherosclerosis due to histological peculiarity. Walls contain only elastic tissue.
Cells of endothelial lining secrete chemicals that prevent atherosclerosis.
Left IMA is preferred due to easier access.