10: Thoracic Wall And Organization Of The Thorax

Front 1

where is the thorax located

Back 1

between the neck and the diaphragm

Front 2

what are the two components of the thorax

Back 2

thoracic wall and thoracic cavity

Front 3

what are the boundaries on the thoracic wall

Back 3

posterior: vertebrae and intervertebral discs from T1-T12

anterior: sternum

lateral: ribs, costal cartiledge

superior: thoracic inlet (opening bounded by vertebrae, manubrium of sternum and ribs), plane at an angle, apices of lungs project into neck

inferior: thoracic outlet, demarcated by diaphragm. separates from abdominal cavity, lower posteriorly

Front 4

describe the 3 parts of the sternum

Back 4

superior: manubrium (jugular notch, clavicular notch, 1st sternocostal joint [no movement with cartiledge to fix with rib cage])

Body, meets manumbrium at manubriosternal joint (sternal angle), some movement, 2nd rib at sternal angle. Ribs 3-7 articulate body, synovial (movable joints)

inferior: xiphoid process, articulates with body at xiphisternal joint

Front 5

which rib do you start palpating and why

Back 5

start with 2nd rib (1st rib is too deep to clavical), use the sternal angle to find it

Front 6

describe the intercostal spaces

Back 6

spaces between ribs, there are 11, named ICS whatever rib number they are below

Front 7

what is the transverse thoracic plane

Back 7

transverse plane from the sternal angle back to the intervertebral disk between T4/T5

marks location of bifurcation of trachea into bronchi, the aortic arch (beginning and end)

Front 8

what are the two ways of classifying ribs and how is each rib classified

Back 8

1. how ribs attach to sternum

true ribs-- attach directly to sternum with costal cartilage (1-7)

false ribs-- indirectly attach to sternum, cartilage attaches to cartilage above it (8-10)

floating ribs-- have no connection to sternum

2. features

typical ribs (3-9)

6 rules for typical ribs: 1. head of rib articulates with vertebral body and intervening intervertebral disk (costovertebral joint, synovial) 2. neck is between head and tubercle 3. articular tubercle articulates with transverse process of vertebra 4. angle (region of maximum curvature) 5. costal groove for VAN 6. shaft ends in cup shaped depression for costal cartilage

atypical ribs (1,2, 10-12)

lack one or more of defining characteristics from above

Front 9

define the costal margin

Back 9

the line created by the costal cartilage of ribs 7-10

Front 10

what are the 2 types of thoracic wall movements?

Back 10

inspiratory: increase thoracic cavity size, decrease pressure, air in

expiratory: decrease size, increase pressure, air out

Front 11

describe the process of diaphragm contraction

Back 11

diaphragm contracts, moves down, increases vertical dimension of thoracic cavity

Front 12

describe the rib elevation in inspiratory movements

Back 12

1. pump-handle: sternum out, rib up (upper ribs)

2. bucket handle: lateral ribs out and up (lower ribs)

increase antero-posterior dimension of thoracic cavity

Front 13

describe the intercostal muscles location, function and arrangment

Back 13

located between ribs

function to keep taught intercostal space (no bulging when breathing) during relaxed breathing

3 layers: external, internal and innermost

Front 14

describe the external intercostal muscles

Back 14

from above rib to below, hand in pocket orientation (lateral to medial down)

don't extend to sternum, replaced by thin external intercostal membrane

raise ribs in forced inspiration

Front 15

describe internal intercostal muscles

Back 15

deep to external, opposite direction of fibers

forced experiation

wrap all the way around from sternum to spine

Front 16

describe the innermost intercostal muscles

Back 16

3 muscle groups connected by membrane

anterior group: transversus thoracis

laterally: innermost intercostal muscles

posterior group: subcostal muscles (forced expiration)

Front 17

describe the location and contents of the neurovascular plane

Back 17

located between internal and innermost intercostal muscles

contains intercostal nerve and vessels (VAN in order)

collateral branches in upper border of rib below

posterior and anterior intercostal arteries and veins

sheltered by costal groove of rib

Front 18

describe the intercostal nerves

Back 18

ventral rami of T1-T11

muscular branches throughout

at midaxillary line, lateral cutaneous branch

just lateral to sternum, anterior cutaneous branch

motor fibers for intercostal muscles, sensory fibers for specific dermatome, sympathetic fibers of blood vessels and sweat glands

no parasympathetic supply to body wall

travel with branches and tributaries of arteries and veins

Front 19

describe the thoracoabdominal nerves

Back 19

intercostal nerves 7-11

travel normally with thoracic neurovascular plane but then exit and continue into abdominal neurovascular plane (between transversus abdominal and internal oblique muscles)

transmit motor, sensory and sympathetic fibers to thoracic and abdominal walls

Front 20

describe the intercostal arteries

Back 20

posterior intercostal artery (most of supply, right off aorta)

anterior intercostal arteries (off internal thoracic artery, not vital)

anastomosis between

Front 21

describe the internal thoracic artery

Back 21

branch of subclavean artery, parallels sternum in descent

around 6th intercostal space, divides into terminal branches

Front 22

describe the musculophrenic artery

Back 22

one of the terminal branches of internal thoracic artery

hugs intercostal margin, lowest branch

Front 23

describe the anterior intercostal veins

Back 23

drain oxygen poor blood away from thoracic wall

mirrors artery, same on both sides

musculophrenic vein, internal thoracic veins, ultimately to brachiocephalic vein

Front 24

describe the posterior intercostal veins

Back 24

different on left/right side, drain most of thoracic wall

Left: to accessory hemiazygos vein or hemiazygos vein, cross midline on vertebra

Right: azygos vein, drains into superior vena cava

Front 25

describe the thoracic cavity organization

Back 25

3 compartments: 2 lateral (contain lungs and pleural sacs, majority of space) and mediastinum

Front 26

what are the subdivisions of the mediastinum

Back 26

superior: thoracic inlet to transverse thoracic plane (sternal angle to intervertebral disk of T4/T5)

inferior: transverse thoracic plane to the diaphragm

Front 27

what are the components of the inferior mediastinum

Back 27

anterior (to heart)

middle (contains heart)

posterior (to heart)

Front 28

describe the layers of the pleural sac

Back 28

visceral pleura: innermost layer, intimately attached to surface of lung tissue, follows fissures

parietal pleura: outer layer

continuous together at point called hilum (doorway into lung)

space between layers is pleural cavity (pleural film for lubrication and surface tension)

Front 29

describe the regions of the parietal pleura

Back 29

cervical-- arches over apecis of lungs

costal-- lines inner wall of thorax

mediastinal-- lateral wall of mediastinum (form pleural sleeve for root of lung, pulmonary ligament)

diaphragmatic-- superior surface of diaphragm

Front 30

what are the lines of pleural reflection

Back 30

where the parietal pleura bends/changes (4 important ones)

R/L sternal line (where mediastinal becomes costal)

R/L costal line (diaphragmatic becomes costal)

right sternal line down to 6th costal cartilage

left has lateral excursion (exposes bare area of pericardium) then down to 6th

costal lines begin at 6th

Front 31

define pleural recesses

Back 31

when lungs are exhaled, space between the visceral and parietal pleura creates recesses

R/L costomediastinal recesses

R/L costodiaphragmatic recesses (lowest points of thoracic cavity (blood or pus settles here)

Front 32

describe the extent of the pleural cavities with reference to lines

Back 32

midclavicular line (visceral to 6, parietal to 8)

midaxillary line (visceral to 8, parietal to 10)

scapular line (visceral to 10, parietal to 12)

2 rib difference

at inspiration, diaphragm moves down, lungs increase, apparent difference decreases

Front 33

define pneumothorax

Back 33

air in the pleural cavity

most common cause: bullet to chest

result is lung collapse

tube thoracotomy (chest tube)