Overview of the Thorax

Question 1

What are the true ribs?

Answer 1

1st - 7th rib

Question 2

What are the false ribs?

Answer 2

8th - 10th ribs

Question 3

What are the floating ribs?

Answer 3

11th-12th ribs

Question 4

What are the atypical ribs?

Answer 4

1st - Scalene tubercle; single facet for articulation with only the T1 vertebra.

2nd - Tubercle for origin of serratus anterior muscle.

10th - Only one facet for articulation with only one vertebra.

11-12th - No necks or tubercles; free floating; articulate with only one vertebra.

Question 5

What are the features of typical ribs?

Answer 5

Head - superior and inferior facets and a crest

Neck - crest

Tubercle - attachment site for muscle

Question 6

What are the parts of the sternum?

Answer 6

Manubrium (T3 - T4)
Body (T5 - T9)
Xiphoid process (T10)

Question 7

What are the joints of the sternum?

Answer 7

Manubriosternal joint

Xiphisternal joint

Question 8

Where is the sternal angle palpated?

Answer 8

T4

Question 9

Where is the sternal angle palpated?

Answer 9

T4

Question 10

What[’s the most common site of sternal fracture?

Answer 10

At the sternal angle (T4)

Question 11

What are the boundaries of the thoracic inlet (superior thoracic aperture)?

Answer 11

T1, the 1st ribs and their cartilages, and the manubrium.

Question 12

What are the contents of the thoracic inlet?

Answer 12

Trachea, esophagus, nerves and blood vessels that either supply or drain the head, neck and upper extremities.

Question 13

What are the boundaries of the thoracic outlet (inferior thoracic aperture)?

Answer 13

T12, the 11th and 12th floating ribs, costal cartilages of the 7 - 10th ribs, and the xiphisternal joint

Question 14

What passes through the thoracic outlet/diaphragm?

Answer 14

“I ate 10 eggs at 12” I8:10E:A12

Inferior vena caval hiatus
Esophageal hiatus
Aortic hiatus

Question 15

What are the muscles of the thoracic cage (outermost to innermost)

Answer 15

External intercostal
Internal intercostal
Innermost intercostal
Transversus intercostal

Question 16

What are the functions of the muscles of the thoracic cage?

Answer 16

External intercostal - elevates ribs in inspiration

Internal intercostal - lowers ribs in forced expiration

Innermost intercostal - Elevates ribs on inspiration

Transversus intercostal - Lowers ribs and costal cartilages

Question 17

What are the orientations of muscle fibers and direction of pull during contraction for the intercostal muscles?

Answer 17

Direction of pull is in the opposite direction of the orientation of the muscle fibers!!

External intercostal - fibers angled down toward front pockets, but pull is upward toward scapula for inspiration

Internal intercostal - fibers angled upward toward breasts, but pull is backward toward back pockets from expiration

Innermost intercostal - fibers angled down toward back pockets, but pull is upward toward breasts for inspiration

Question 18

What is the change in the vertical diameter of the chest upon inspiration and expiration?

Answer 18

The vertical diameter increases upon inspiration as the diaphragm descends, and decreases upon expiration as the diaphragm ascends.

Question 19

What is the change in the transverse diameter of the chest upon inspiration and expiration?

Answer 19

“Bucket handle motion”

The transverse diameter increases as intercostal muscles contract for inspiration.

Question 20

What is the change in the anteroposterior diameter of the chest upon inspiration and expiration?

Answer 20

“Pump handle motion”

Sternal ends of ribs 2 - 6 rises.

Question 21

What innervates the diaphragm?

Answer 21

C3,4,5 - phrenic nerve

“3,4,5 keeps the diaphragm alive”

Question 22

What is the vasculature of the thoracic wall?

Answer 22

(V.A.N, vein at the top, artery in the center, nerve at the bottom)

The intercostal vein, artery and nerve lay within the costal groove of each rib.

Question 23

What vessel can be punctured during chest tube entry?

Answer 23

The nerve is relatively exposed during procedures through the ribs (chest tubes, etc.) so enter at the superior surface of the rib at the intercostal space.

Question 24

What are the arteries of the anterior thoracic wall and where do they come from?

Answer 24

The anterior intercostal arteries supply the anterior thoracic wall and they come from the M.I.S - musculophrenic, internal thoracic, and supreme thoracic arteries.

Question 25

What are the arteries of the posterior thoracic wall and where do they come from?

Answer 25

The posterior intercostal arteries supply the posterior wall and they come from the aorta and costocervical trunk.

Question 26

Where do the intercostal veins drain?

Answer 26

Into the azygos and hemiazygos veins.

Question 27

What is the nerve supply of the intercostal muscles?

Answer 27

Intercostal muscles are innervated by the intercostal nerves, which are VENTRAL RAMI of thoracic nerves

Question 28

What are the dermatomes of the thoracic region?

Answer 28

C4 - clavicles and jugular notch
T2 - sternal angle
T4 - level of the nipples

Question 29

What are the boundaries of the superior mediastinum?

Answer 29

Superior - thoracic inlet

Inferior - T4-T5

Question 30

If you’re a child, what is located in your anterior mediastinum?

Answer 30

The lower portion of the thymus.

Question 31

What are the 7 contents of the superior mediastinum?

Answer 31

Aortic arch (brachiocephalic trunk, left common carotid, left subclavian artery)

Esophagus

Phrenic & Vagus nerves (recurrent laryngeal nerve)

Superior vena cava (Left and right brachiocephalic veins come together to form vena cava)

Thoracic duct
Thymus
Trachea