thorax Flashcards
how many pairs of ribs do we have
12
what types of ribs do we have
7 pairs of true ribs (1-7)
3 pairs of false ribs (8-10)
2 pairs of floating ribs (11 + 12)
what do true ribs connect to
sternum via their own costal cartilage
how do false ribs attach to the sternum
by merging together and attaching to the costal cartilage of rib 7 (forms the costal margin)
so indirect connection with the costal cartilage
how do floating ribs connect to the sternum
DO NOT as they do not have costal cartilage
what do all ribs attach to
thoracic vertebrae of spine (in thoracic region of the spine) posteriorly
so what is the ribcage formed by
rib bone becoming costal cartilage (costal bc in region of the lungs) which then attaches to sternum itself
what is located between the rib and where it becomes costal cartilage
costo-chondral junction
what level does the
a) 1st rib
b) 2nd rib
attach
a) T1 vertebra = to manubrium portion of sternum
b) T12 vertebra
what is the space between each of the ribs called
intercostal space
what 3 parts make up the sternum from top to bottom
1) manubrium
2) body of the sternum
3) xiphoid process
what bone attaches to the scapular on the posterior aspect of the ribcage
clavicle
which 2 openings allow structures to enter and leave the rib cage
1) superior thoracic aperture = structures pass from h&n or upper limb into thoracic region
2) inferior thoracic aperture = pass from thoracic region to abdominal region
what 3 functions does the ribcage serve, explain these
1) protection = for vital organs (heart, lungs) + upper abdominal organs (liver sits high up on rhs and pushes up into the diaphragm) + spleen on lhs
2) support = all bones have muscles attached to them, ribcage provides stable point of attachment for lots of muscles in thoracic region + muscles that help control movement of upper limb (eg pecks, a few muscles in top of arms / shoulders)
3) respiratory movements = breathing in + out changes thoracic vol (essential for pressure change and air to be drawn in / forced out)
what is the diaphragm
high spongy sheet of thin, strong muscle that separates thorax from the abdominal region and covers the entire inferior thoracic outlet
how does the diaphragm sit
domes superiorly into rib cage when relaxed
higher on rhs bc of liver
what does the diaphragm do during
a) inspiration
b) expiration
a) contracts so muscle fibres pulled tight causing muscle to be pulled down flat (more space inside rib cage for lungs to expand and take in as much O2 as possible)
b) relaxes
what allows passage of structures through the between thorax and abdomen
apertures in its posterior
what level does the inferior vena cava pass through the diaphragm at
T8 (thoracic vertebra 8)
- remember - vena cava has 8 letters so T8!
what level does the inferior oesophagus pass through the diaphragm at
T10
- and oesophagus has 10 letters
what level does the inferior / descending aorta pass through the diaphragm at
T12
which nerves supply the diaphragm and what are they made up of
PHRENIC NERVES (r+l one)
made up of contributions from cervical spinal nerves 3, 4, 5
C3, C4, C5 keeps the diaphragm alive!
what are the 3 layers of intercostal muscle
external (also have an external intercostal membrane - lies medial to external muscle, v thin and see through)
internal (fibre directions lay perpendicular to external)
innermost
explain the innermost intercostal muscles
- v thin layer of muscle, follows same fibre direction as internal
- only used when forcing air out of lungs - accessory muscle of respiration
how do external intercostal muscles run and what does this mean when we breathe in
downward direction
from upper rib and latch onto rib below
external contract pulling inferior rib upwards
how do internal intercostal muscles run and what does this mean when we breathe out
upward direction
from lower rib and latch onto rib above
internal contract pulling ribs down to dec space in thoracic cavity so we’re forcing air out through lungs
which three vessels correspond to the intercostal spaces
what is there role
where are these found
intercostal vein (posterior intercostal veins drain into azygous vein - hemiazygous and accessory azygous veins)
intercostal artery (posterior intercostal artery arise from descending aorta)
intercostal nerve (sympathetic contributions from sympathetic chain)
supply intercostal muscle / take blood away
found under the costal groove (on lower portion of inner surface of each of rib) + protects the structures
what is the structure of the intercostal space
1) external intercostal muscle most superficial
2) then internal
3) then the neurovascular bundle (ALWAYS runs vein, artery, nerve top to bottom VAN)
4) deep to this is innermost
how do intercostal muscles help to move the position of the ribcage
- ribcage moved up + out of sternum when external intercostal in upper ribs pull to move ribs up in inspiration which increases anteroposterior diameter making more room for lungs to expand
- when external intercostal contract, lower ribs move up + out increasing diameter across entire ribcage (transverse diameter) in inspiration
what are the 2 divisions of the thoracic cavity
superior mediastinum inferior mediastinum (made up of anterior, middle + posterior portions)
mediastinum encloses / contains heart, major vessels + nerves, trachea (carrying air to lungs) + oesophagus
what happens to the trachea once in the thoracic region
divides into 2 primary bronchi
what is present either side of the mediastinum
pleural cavities consisting of 2 pleural sacs which cover the lungs
what is the name of the point where the manubrium meets the sternum and what does it allow us to do
STERNAL ANGLE
- know what separates superior mediastinum (run above it) from the inferior (below it)
- 2nd rib attaches at level of it
what level would the sternal angle cut through
T4/5 vertebral disc
so superior mediastinum above level of T4/5 and inferior below
what structures are contained in the superior mediastinum
thymus trachea oesophagus vagus nerves phrenic nerves left recurrent laryngeal branch of the vagus nerve thoracic duct great vessels (aorta, superior vena cava, pulmonary trunk - artery + vein)
what structures are contained in the inferior mediastinum
anterior = area between posterior aspect of sternal body + anterior aspect of pericardium. contains ligaments binding fibrous pericardium to posterior aspect of the sternum with 1/2 lymph nodes + small vessels
middle = heart which is surrounded by 1 fibrous pericardium layer (tough sac) externally
2 serous pericardium layers (secrete serous pericardial fluid = facilitates movements associated w beating of heart) underneath between which is the pericardial cavity (parietal layer on inner surface of fibrous flips to make continuous visceral layer)
Serous pericardium extends around aorta + pulmonary trunk as they pass through fibrous pericardium and surrounds superior + inferior venae cavae + 4 pulmonary veins near their terminations
the visceral serous pericardium (epicardium) forms part of heart wall
also pulmonary trunk, the two bronchi, the ascending aorta and the terminal part of the superior vena cava
posterior = oesophagus, descending aorta, thoracic duct, azygous + hemiazygous vein, sympathetic chain, lymph nodes, thoracic splanchnic nerves
what is the function of the
a) sympathetic chain
b) the thoracic duct
a) helps control nervous impulses to heart and lungs - chain of sympathetic nerves, run paravertebrally down through thoracic region to abdomen, only receive contributions in thoracic region, contain different ganglia (cell bodies)
b) v deep between aorta and azygous vein, biggest lymph vessel in body, takes lymph back from body back to venous system so it can be recirculated
what is the function of the azygous vein
takes blood back to inferior vena cava from lower portions of body
drains digestive tract and posterior intercostal veins
describe the aorta
ascending aorta comes out of heart, the arch of the aorta gives off branches to the h+n then loops downwards becoming the descending aorta which supplies blood to the rest of the trunk (abdomen, pelvis, lower limbs)
what are the 3 branches coming directly off of the aorta
1) brachiocephalic trunk = first branch of aorta
2) left common carotid artery = supplies left of h+n
3) left subclavian artery = supplies left upper limb
what does the braciocephalic trunk split into
right subclavian artery = supplies right upper limb
right common carotid artery = supplies left of h+n
what veins drain into the heart
right internal jugular vein and right subclavian vein combine to form the right braciocephalic vein
same 2 veins combine to form braciocephalic vein on the left
the 2 braciocephalic veins combine to form the superior vena cava which drains into right atrium
what are the 3 branches of the thoracic aorta
1) paired, segmental branches to the body wall = ie intercostal arteries
2) paired arteries to paired internal organs = ie bronchial arteries (go to bronchi)
3) ventral, unpaired arteries to to GIT = ie oesophageal arteries
explain the intercostal arteries given off by the aorta
12 sets of posterior intercostal arteries given off directly from the aorta on both sides (12 sets so 1 for each intercostal space)
what surrounds the lungs and what is it
PLEURA
membraneous sac enclosing the pleural cavity
lung pushes its way into the sac until the 2 layers of the pleura are against each other
what are the 2 layers of pleura
1) visceral pleura = at front, inner membranous layer of tissue directly on / covering the lung and adjoining structures
2) parietal pleura = at back, outer layer of tissue against / covers inside of thoracic wall
what is in between the 2 layers of pleura and what does it aid with
PLEURAL CAVITY
- thin layer in middle
- contains thin film of serous fluid
- helps maintain lubrication so lungs can expand and contract wout friction
- creates surface tension between parietal and visceral layers to aid inspiration (when ribcage moves up + out parietal pleura is pulled with it creating tension between the 2 layers so visceral layer is pulled outwards to help lungs expand + take air in)
name the structures entering the lungs from largest to smallest
1) trachea = descends as a single tube through the superior mediastinum
2) r+l primary bronchi = trachea divides into these at level of T4, this bifurcation point is called the carina
3) secondary bronchi + bronchioles = bronchi pass through their hilum before dividing into these
4) alveoli
what are the structures of the lungs
1) apex = the top of the lungs
2) superior lobe
3) middle lobe (right only)
4) inferior lobe
5) oblique fissure
6) transverse / horizontal fissure (right only)
what does the oblique fissure do
separates superior and inferior lobes
on both sides
what does the horizontal fissure do
separates the superior and middle lobes
on right side
what does the left lung have that the right does not
LINGULA
tongue like projection of its superior lobe
how do structures enter and leave the lung
HILUM OF THE LUNG
- medial aspect of lung next to the heart
- corresponds to 4-5th costal cartilages
- corresponds to T5/7 poseriorly
- left lung hilum = pulmonary artery superiorly, primary / main bronchus dividing into 2 secondary bronchus, 2 pulmonary veins inferiorly, pulmonary ligament (pleura gathers together from each side to form it)
- right lung hilum = same but 2 pulmonary arteries anteriorly, bronchus has thick wall (3 secondary bronchi) + lies posteriorly, 3 pulmonary veins in inferior
1 secondary bronchi for each lobe
what two impressions do the lungs have (bc lungs are soft)
1) cardiac impression = made by heart, deeper on left lung as heart points heavily towards lhs of thorax
2) aortic impression = made by arch of aorta as it arches and descends near posterior border of left lung / over top of hilum of left lung
3) azygous vein impression = posterior to hilum + over top of it in right lung
4) rib impressions = costal (lateral) surfaces of both lie alongside ribs so bear impressions from the ribs on this surface
what are the
a) right
b) left
AV valves called
a) tricuspid valve (has 3 cusps)
b) mitral / bicuspid valve (2 cusps)
what are the
a) right
b) left
semilunar valves called
a) pulmonary
b) aortic
what are the cusps of the AV valves attached to
papillary muscles (in wall of ventricle) which has chordae tendineae (tendinous strands referred to as heart strings) coming off it
how do the papillary muscles prevent backflow
- when heart contracts they become tight and contract
- chordae tendineae become taute
- cusps of valves are forced closed
- bc chordae tendineae are pulled tight the valve cannot invert on itself so blood is forced out through aorta / pulmonary artery
how does heart contract, what does this allow
- contractions in heart sent down through middle causing heart to contract from bottom upwards
- allow blood flow from atria to ventricle
which blood vessels supply the heart muscle
coronary arteries
- right and left coronary arteries
what are the branches of the right coronary artery
it emerges from aorta
curves around heart in a groove (coronary sulcus - coronal = crown) to the posterior aspect
then gives off
1) right posterior descending / intraventricular
2) right marginal branch = runs along inferior border of heart
what do branches of the right coronary artery supply
- conducting centres of the heart (SAN + AVN)
- these control impulses through atria down towards ventricle to enable heart to contract
what are the branches of the left coronary artery
emerges from aorta
1) left anterior descending artery
2) circumflex artery (curves posteriorly on heart)
what do branches of the left coronary artery supply
mainly left ventricle
how is deoxygenated blood carried away from heart muscle and back to heart
CORONARY VEINS
great cardiac vein collects 2/3 blood from heart muscle
it drains into the coronary sinus which empties into right atrium
sits in coronary sulcus
anterior cardiac veins (3–4) open directly into right atrium
what are the pec muscles
pec major
pec minor
surround the thoracic cage
what does the vagus nerve do in the thorax
goes from brain down TO the colon
gives of recurrent larangeal nerve which supplies the larynx
how do interior intercostal arteries arise
internal thoracic artery (branch of right subclavian artery) gives rise to them
it also gives of musculophrenic artery
how does the trachea maintain its structure
rings of cartilage
describe the
a) posterior
b) anterior border of lungs
a) much wider than anterior, smooth
b) much thinner, not smooth
what is visible on costal (back) surface of lung
ridges where ribs cause an indent
what heart structure is used in development, what does it become in adults
ductus arteriosis = shunts oxygenated blood from pulmonary trunk (oxy blood carried into body by umbilical vein) into aorta so it can go through descending aorta
becomes ligamentum arteriosum
not used as adult
describe internal features of the right atrium
- muscular inner wall (pectinate muscle)
- smooth muscle = crysta terminalis
- 2 above help distinguish right atria
- 3 cusps of av valve
- fossa ovalis = indentation in adult heart (during development = hole shunting blood flow from right to left atrium) called foramen ovali in development
- left atrium similar
describe internal features of the right ventricle
- inner surface = trabeculae carneae muscle (to which cords are attached + extensions of these muscles are the papillary muscles)
- deep to trabeculae carneae = papillary muscles project out into ventricular lumen (attached to chordae tendineae)
- tricuspid valve = papillary muscle to chordae tendineae to tricuspid valve
- papillary muscle + chordae tendineae prevent inversion of cuspid valve when ventricle contract
- moderator band comes off septum, helps slow speed of conduction through ventricles so they contract AFT atria have contracted
- 3 cusps of SL (2 anteriorly, 1 posteriorly) valves in pulmonary trunk (pulmonary valves)
describe internal features of the left ventricle
- trabeculae carneae
- thicker papillary muscle and walls
- chordae tendineae go up to inferior portion of heart toward a cusp of av valve
give the names and location of pleura covering the lungs (as pleura changes name depending on where it is)
- visceral plural = tightly directly stuck to lung
- folds on itself to become parieral pleura
- cervical pleura = if take deep breath lungs come up into clavicle / cervical region
- costal pleura = directly in contact w ribs
- diaphragmatic parietal pleura = on top of diapraghm
- in between the pleuras (space between them)
parietal pleura have mediastinal, costal, diaphragmatic pleura cervical parietel pleura
function of costal cartilage
expansion of the thorax and extension of the ribs
contributes to elasticity of walls of thorax
what distinguishing features do thoracic vertebrae have
(superior and inferior) facets on the sides of the vertebral bodies for articulation with the heads of the ribs, and facets on the transverse processes of all (except 11th and 12th) for articulation with rib tubercles
demifacet for rib head
how do adjacent vertebrae articulate
upper surfaces of lamina
where are visceral and parietal layers of pleura continuous
at hilum of lung
a) function of the thymus in children
b) how thymus structure changes with age
a) production and maturation of T-lymphocytes or T cells
b) shrinks rapidly with age from puberty(older individuals at greater risk for life-threatening infections)
what is the posterior mediastinum is bounded by
a) anteriorly
b) posteriorly
c) laterally
a) posterior aspect of fibrous pericardium
b) anterior surface of thoracic vertebral bodies T4- T12
c) mediastinal parietal pleura
function of
a) hemiazygos
b) accessory hemiazygos veins
a) drain left mediastinum and left lower esophagus
b) with azygous = drain most posterior intercostal veins on lhs of body
what could cause “mediastinal shift” what are the consequences in the thoracic cavity
volume expansion or loss on one side of thorax
compression of lung on unaffected side
life-threatening = pressure on great vessels causes dec in venous return, reduced CO, decreased BP and hypoxia = lead to shock
what stage of the cardiac cycle does blood flow into the coronary arteries
peaks during ventricular diastole
consequence of a blockage in the anterior interventricular (left anterior descending) artery?
myocardial infarction
high fatality risk
what separates the rough and a smooth portion of relatively thin wall of the right atrium
ridge = the crista terminalis internally
smaller rough area = auricular appendage, w elevations (pectinate muscles)
smooth walled portion (sinus venarum) receives openings of superior and inferior venae cavae and coronary sinus
describe internal features of the left atrium
- thin walled
- smooth and roughened portion
- roughened portion = auricular appendage
- smooth walled portion is formed by incorporation of the 4 pulmonary veins during development
