Chest anatomy, heart and lungs

on this mannequin again we can see the

larynx up here and the thyroid gland is

over the top of the trachea this is the

thyroid gland we can see the major

vessels in the neck the carotid artery

taking blood up to the brain and the

jugular vein bringing blood back down

here we can see the left clavicle and

the right clavicle and the first rib

there one two three four five six seven

eight nine and ten

connected to the sternum via the costal

cartilages on this model we don't see

any intercostal muscles we see straight

through to the lung fields beneath and

if we take these lungs off well here we

can see the underside with the Hmong and

we can see the domed nature of the

diaphragm so the diaphragm domes up and

then flattens and when the diaphragm

contracts it actually moves down and

flattens when his felt like this that

means it's in a relaxed state and we can

see that the diaphragm domes are quite a

long way because that's the base of the

sternum here and we notice that because

the sternum is a flat bone the red bone

marrow is inside the bone marrow is red

it is bone marrow that produces blood

cells particularly red blood cells are

produced in the red bone marrow inside

flat bones as such as the sternum

here we see the heart and these large

blood vessels this is the aorta taking

oxygenated blood to the body this is the

superior vena cava bringing deoxygenated

blood back from the body and here we see

the pulmonary artery taking blood to the

lungs the main trunk of the pulmonary

artery goes back then it quickly divides

into two one branch go into each lung

and if we look in the lung fields in


we can see that the pulmonary artery

vessels are in blue because they're

taking deoxygenated blood into the lung

to be oxygenated this blood will then go

through the pulmonary capillaries which

are in close association with the

alveoli when the blood is oxygenated it

will drain back in the red vessels which

are branches of the pulmonary veins so

the pulmonary veins in the lungs are in

red because they're bringing back the

oxygenated blood because remember a vein

is defined as any structure carrying

blood towards the heart whereas an

artery is any structure carrying blood

away from the heart and here we also see

some of the bronchial passages taking

air to all parts of the lung taking air

into the lung and allowing air to go out

of the lung as well and here we see

cross-sections of the ribs the first rib

second third and fourth

and if we look at these closely we see

that again the bone marrow in the ribs

is also red bone marrow producing blood

cells and between the ribs we can see

the intercostal muscles here here here

here so the ribs and the intercostal

muscle are comprising the chest wall

nasty return this manikin to the side

and we can look in here what we see

there is the parietal pleural membrane

the provider floor membrane is lining

the inside of the thoracic cavity the

visceral pleural membrane would be

lining the surface of the lung in health

we notice that there's no gap between

the surface of the lung which would have

the visceral pleura membrane attached to

it and the inside of the thoracic cavity

with the parietal pleura or membrane

attached to it that's because the

visceral pleura membrane is completely

sucked up to the parietal pleura

membrane there is only a potential space

between the visceral and parietal

membranes in health

and if we look at this lump this lung is

arranged in cross-section so you can get

some light on that and what we see here

across sections of blue vessels and the

blue vessels are going to be arterial

vessels taking blood to the lungs to be

oxygenated and here we see

cross-sections of red vessels and the

red vessels are going to be

cross-sections of pulmonary veins taking

blood back to the heart after it has

been oxygenated and also in various

parts of the lung we see cross-sections

of the bronchial passages still

supported by rings of cartilage to keep

them patent taking air in and out of the

lungs from the large Airways such as the

takea down all the way to the

bronchioles and the alveoli and here

again we see the domed nature of the

diaphragm this dome of muscle when it

contracts it flattens to increase the

volume of the thoracic cavity at the

same time the intercostal muscles

contract to move the chest wall up and

out both of those effects will increase

the volume of the thoracic cavity as you

increase the volume you reduce the

pressure meaning the air is sucked in to

the lungs

humans are negative pressure ventilator

x' dependent on the action of the

diaphragm and the ribs and intercostal

muscles the diaphragm is actually

innovated by phrenic nerves the two

phrenic nerves which leave all the way

up at the cervical vertebrae into

Michael nerve roots three four and five

coming down through the chest to the


you can remember that because see three

four and five

keep the diaphragm alive where is its

spinal nerves supply the intercostal

muscles with neurological innovation so

a very interesting model of the thoracic

cavity here we can actually see the

rings of cartilage on the trachea just

before the trachea bifurcates into the

left and the right main bronchus and we

can see this major airway in this model

here here we see the trachea left main

bronchus right main bronchus we see that

the left main bronchus divides into two

loba bronchi superior lobe and inferior

lobe we can see that the right main

bronchus divides into three one two

three lobo bronchi go to the left

superior lower and middle Lopes we see

the rings of cartilage keeping the

Airways open we see further bronchial

passages comprising the bronchial tree

go to the pulmonary segments and of

course these further subdivide taking

air to all parts of the lung and you can

see why this is called a bronchial tree

because if we turn it upside down it

looks just like her

trick at the top here we see the thyroid

cartilage which is part of the larynx

and here we see the first ring of

cartilage which is called the cricoid

cartilage and this first ring of

cartilage the cricoid cartilage is the

only cartilage in the trachea which is a

complete ring of cartilage the others

are C shaped rings to allow distortion

as a result of food policies going down

the esophagus but the cricoid cartilage

is a complete ring and between the

thyroid cartilage and the cricoid

cartilage is the cricothyroid ligament

that ligament there is the cricothyroid

ligament and you can feel that in your

own neck if you palpate the little gap

between that bit and that bit and then

occasionally if the airway is blocked in

an emergency medical situation as a

procedure called a cricothyrotomy where

a small airway can be put through there

into the trachea to allow breathing to

take place here we see part of the

thyroid gland which is only shown in his

right lobe in this model and we can

actually open this to look inside again

there we see the thyroid cartilage from

the side and the cricoid cartilage from

the side before the C shaped rings of

cartilage that comprise the trachea and

if we take this off

here in cross-section here we see the

vocal cords and it's these vocal cords

that vibrate to generate the voice so

this would actually be the front on this

side and this structure here is the

epiglottis and during swallowing this

will fold down to close the glottis

which is the top of the airway to allow

food to go down the posterior esophagus

which would run at the back here the

upper part of the airway of course it's

absolutely vital that these Airways are

kept patent to allow air into the lungs

and out of the lungs