Thoracic wall/cavity/mediastinum

Question 1

Sternal angle

Answer 1

manubriosternal joint
articulation with rib 2
creates Transverse Thoracic Plane which crosses thru the disc b/w TV4 and TV4
–>divides superior and inferior mediastinum

Question 2

Thoracic Inlet

Answer 2

1st TV
1st rib
manubrium
Oblique and anterior-inferiorally from TV1–>manubrium
need to be aware of pleura in this area during surgery or injury

Question 3

Thoracic outlet (inferior aperture)

Answer 3

12th TV
11th and 12th ribs
costal margin 
xiphisternal joint 
Closed by diaphragm 
oblique and anterior-superior 
need to be aware of pleura in this area during surgery or injury

Question 4

ribs

Answer 4

true=1-7
false=8-10
floating= 11-12
3-9 are typical

Question 5

1st Rib

Answer 5

no angle
lies in a more transverse
tubercles for scalene muscles
grooves for subclavian a. and v.

Question 6

2nd rib

Answer 6

serratus anterior tuberosity on superior surface

Question 7

10th rib

Answer 7

single articular facet for the body of TV10

Question 8

11th and 12th rib

Answer 8

single articular facet on head, no neck or tubercle (don’t articulate with TP of TV 11 and 12)

Question 9

Sternocostal joint

Answer 9

articulation b/w costal cartilage and sternum
supported by anterior and posterior radiate ligaments
1st SC joint is synchondrosis—>no movement
2-7 are synovial plane

Question 10

Costochondral joints

Answer 10

articulation b/w rib and costal cartilage

synchondroses, **frequently dislocated, even in minor trauma

Question 11

Costovertebral joint

Answer 11

b/w rib head and vertebral bodies/IV discs
synovial plane
radiate ligaments support capsule

Question 12

Costotransverse joint

Answer 12

b/w rib and vertebral transverse process
synovial joints
not on 11 and 12
supported by superior costotransverse ligament

Question 13

Pump handle motion

Answer 13

increase AP diameter
rotation at costotransverse joint elevates anterior part of ribs

**first rib is fixed

Question 14

Bucket handle motion

Answer 14

gliding at posterior costovertebral and costotransverse) cases elevation of lateral portion of ribs
increases the transverse diameter of thoracic wall

Question 15

Thoracic diaphragm

Answer 15

contraction–> increase in vertical diameter
n=Phrenic (C345)
rest–>4th ICS

rest= TV8
Deep inspiration= TV11
Deep expiration= TV4
forced inspiration lowers it 2 vertebral bodies

Question 16

Intercostal nn.

Answer 16

11 pairs + 1 pair of subcostal

formed by ventral rami of thoracic spinal nn.

1) Motor innervation to thoracic wall muscles
2) preganglionic SNS via 14 pairs of white rami to the sympathetic chain
3) Postganglionic SNS via 31 pairs of grey rami to glands, smooth muscles, arrector pili etc

Question 17

Dermatomes of thoracic wall

Answer 17

T4=Nipple
T6=Xiphoid
T10= Umbilicus***
note that C4 (shoulder) abuts T2 due to the brachial plexus.

Question 18

Anterior IC arteries

Answer 18

9 pairs arise from

1) Internal thoracic –>1-6
2) Musculophrenic a. (branch of internal thoracic) –>lower ICS

anastomose with posterior

Question 19

Posterior IC arteries

Answer 19

11 pairs
arise from
1) Thoracic (descending) aorta–>3-11
2) Costocervical trunk–>1-2

higher pressure system

Question 20

Internal thoracic a.

Answer 20

branch of subclavian 
gives off
1) anterior IC a. 1-6
2) Musculophrenic a. -->IC a. 7-9
3) Superior epigastric a.

Question 21

Superior Intercostal vein

Answer 21

gets drainage from 1-3rd intercostal veins

drains into azygous (R) or brachiocephalic (L)

Question 22

Azygos vein

Answer 22

from right ascending lumbar v and right subcostal vv.

tributaries: R posterior intercostal veins, hemiazygos, and accessory hemiazygous….plus tributaries from IVC

at TV4 it enters the SVC
**collateral circulation b/w SVC and IVC

Question 23

Hemiazygous

Answer 23

gets blood from inferior 3 posterior IC veins

joins azygos at TV9

Question 24

Accessory hemiazygos

Answer 24

drains left posterior IC veins 4-8

Question 25

Superior mediastinum

Answer 25

above the transverse thoracic plane
TV1-->TV4
Thymus
R/L brachiocephalic vv. 
SVC
Aortic arch and its branches
ligamentum arteriosum 
Trachea
esophagus 
thoracic duct 
sympathetic trunk 
phrenic n
Vagus n.

Question 26

Vagus N.

Answer 26

runs with common carotid aa.
Posterior to root of lung
carries preganglionic PSNS–>thoracic autonomic plexus
branches into left recurrent laryngeal n–>laryngeal muscles (causes hoarseness if damaged)

Question 27

Anterior mediastinum

Answer 27

below transverse thoracic plane and anterior to pericardium

thymus, sternopericardial ligmants, fat, lymphatics, CT

Question 28

Posterior mediastinum

Answer 28

inferior to transverse thoracic plane and posterior to the pericardium
Esophagus
azygous system
thoracic duct and nodes
sympathetic trunk (chain ganglia) and splanchnics

Question 29

constrictions of esophagus

Answer 29

1) CV6= paryngoesophageal
2- TV 4-5 broncho-aortic
3) TV 10 diaphragmatic

Question 30

thoracic duct

Answer 30

part of posterior mediastinum–> lymph from 3/4 of the body

begins at LV2 at cisterna chyli ascends to azygous–>empties into the Left venous angle with subclavian trunk and jugular vein
–>all lower lymphatics drain into thoracic duct and into LVA

Question 31

Greater splanchnic n.

Answer 31

preganglionic SNS

T5-9

Question 32

Lesser splanchnic

Answer 32

preganglionic SNS

T10-11

Question 33

Least spanchnic

Answer 33

preganglionic SNS

T12