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Thorax: General Information

Shape: abnormal cylinder; two openings-superior and inferior; superior is small and narrow superior thoracic aperture and it has a large domed bottom part via the diaphragm; Bony cage + exterior components/pectoral regions

Contents: thorax is divided into two pleural (R and L) with central pericardial cavity between them containing the heart (perfusion of blood) and lungs (gas exchange)

Functions; conduit: allows structures of head and neck to travel through it, bony structure providing protection around the soft viscera, solely responsible for gas exchange/ respiration; central pump of the body is located

Boundaries: looking down you see the trachea and the major vessels; see rib1, vertebral body 1, clavicle, and manubrium


Superior Boundary of the Thorax

Superior thoracic aperture, 1st ribs, 1st vertebra, trachea, clavicle, coracoid process, subclavian arteries and veins (R and L), esophagus, brachial plexus, scapula, and axillary inlet



Inferior Boundary of the Thorax

The diaphragm attaches to ribs 11 and 12
Body of vertebra XII posteriorly
Distal cartilaginous ends of ribs VII to X, which unite to form the costal margin anteriolaterally
Anteriorly: xiphoid process of the sternum
Thoracic cavity is a slanted structure
Everything superior to the diaphragm is thoracic cavity


Line of Reference

1. Midclavicular: halfway down the clavicle and straight down the ribs (MCL), one of the coordinates when describing the topography of the body

2. Midaxillary line: look at patient laterally ask them to raise arm, draw line down the ribcage

These are important for medical interventions in the thorax that are life threatening


Pectoral Region Compartments

1. Superficial: mammillary glands
2. Deep: musculature over the cage


The Breast

Modified sweat gland with series of suspensory ligaments for support and structure continuous with the dermis
When looking at breast, most is on the front, but also has an axillary tail in the axillary space; when preforming breast exam, need to also check the axillary process where tumors can hide


Breast Vasculature and Lymphatics

Vasculature: lateral thoracic, internal thoracic, and subclavian arteries

Feeders = pectoral branch of acromial artery and lateral thoracic artery both coming off axillary artery, but more medially are the mammillary branches coming off the internal thoracic artery

Venous drainage will parallel venous supply
Lymph node involvement= metastases

Surface anatomy of the breast around the nipple is divided into three sections:
1. Lateral Breast= lymph flow to axillary nodes for metastasis
2. Medial Breast: lymph flow to parasternal nodes
3. Deep/inferior lymph flows down (gravity)


Breast Cancer

Supported in dermis in body wall by ligaments of Cooper

Mass in adipose= supply tension on ligaments, which causes pitting or dimpling of skin, called the Peau D’Orange
The mass will grow and put tension on suspensory ligaments causing puckering= highly suggestive of mass present; 9/10 means tumor or other mass
Men are also susceptible to breast cancer


Pectoral Musculature

Deep to breast musculature
Pectoralis major, minor, and subclavis

Pectoralis Major: large sheet muscle from sternum to proximal humerus

Pectoralis Minor: underneath pectoralis major and passes from the anterior surfaces of ribs 3-5 to the coracoid process of the scapula

Subclavis: underneath pectoralis major; small and passes laterally from the anterior and medial part of rib I to the inferior surface of the clavicle


Pectoralis Major

Origin: Medial half of clavicle and anterior surface of sternum, first seven costal cartilages, aponeurosis of external oblique

Insertion: Lateral lip of intertubercular sulcus of humerus

Innervation: Medial and lateral pectoral nerves

Function: Adduction, medial rotation, and flexion of the humerus at the shoulder joint



Origin: Rib I at junction between rib and costal cartilage
Insertion: Groove on inferior surface of middle third of clavicle

Innervation: Nerve to subclavius

Function: Pulls clavicle medially to stabilize
sternoclavicular joint


Pectoralis Minor

Origin: Anterior surfaces of the third, fourth and fifth ribs, and deep fascia overlying the related intercostal spaces

Insertion: Coracoid process of scapula

Innervation: Medial pectoral nerves

Function: Depresses tip of shoulder; protracts scapula


Skeletal Structure of Thorax

Osteology of the thoracic cage: posterior surface has spinal column, anterior is sternum, and ribs are lateral
Never have a direct bone to bone connection
Costal condral junction: cartilage to ribs= NEED TO BREATH because if bone to bone we wouldn’t be able to breath


Structure of the Sternum

Manubrium: articulation with clavicle, rib 1, and rib 2 (body shares connection to rib 2)
3,4,5,6,7 ribs= cartilaginous connection with sternum
True Ribs: 1-7

8,9,10 are specially connected to the sternum; don’t have direct cartilaginous connection to sternum, but articulate with costal cartilages of the ribs above
False Ribs: 8-12
Floating Ribs: 11 and 12 don’t have a connection to anything


Vertebral Structure

Vertebral body: weight bearing
Pedicle: connect arch to body (arch made of lamina)

T1-9 have demifacets because half of the articulation; rib 1 will articulate with T1, and so on… superior and inferior demifacet… T2 and T3 will articulate with a rib inferior and superior

Superior articular process allowing for articulation with superior vertebra, and two inferior for the inferior vertebra

T1 will have small vertebral body and as we move down they get bigger
Rib 10 with vertebrae 10
Rib 1 T1, Rib 10 T10,…. Everything else will share articulations ex. T2 and 3 articulate with Rib 2
No articulation point on transverse process


Rib Structure

Breast bone to spinal column
Head of rib to connect to demifacets
Articular facet on tubercle for connection to transverse process
All ribs have angles, where it starts to bend

External and internal surface of rib
Internal: look at posterior and see costal groove for location of artery, vein, and nerve


Special Features of Ribs I, XI, and XII

Rib1 is flatter, and unique because see circular pits on the external surface for large vessels like the subclavian artery and vein; bump in between the vessels is the scalene tubercle

Rib 12 looks like bony finger with not much of a curvature same with Rib11

The rest of the ribs are curved
Different and unique: Ribs 1, 11, 12
Take all the ribs and generally size up the ribs, where 7 is the largest


Vertebral Joints

Reinforced with ligaments
No place in the body has bone to bone connections, but has synovial joints that don't provide much give
Synovial Joint: series of ligaments with joint capsule

Costotransverse Joints: synovial joints between tubercle of a rib and the transverse process of the related vertebra

Costotransverse Ligaments: medial to the joint and attaches the neck of the rib on the medial and lateral sides of the joint

Lateral Costotransverse Ligament: is lateral to the joint and attaches the tip of the transverse process to the nonarticular tubercle of the rib

These ribs are held by at least 3 ligamentous connections allowing some space for movement, but not too much


Interchondral, Sternocostal, and Fibrocartilaginous Joints

Interchondral Joints: cartilage to cartilage connections have synovial joints between ribs 6/7, 7/8, 8/9, and 9/10

Sternocostal Joints: between upper seven costal cartilages and the sternum

Rib 1 = fibrocartilaginous joint and very anchored


Thoracic Wall Musculature

Intercostal muscles: in between ribs with internal, external, and innermost layers

External are oriented in one plane and the internal in another plane; why are they in different directions? To have higher strength and resistance

External “hands in your pocket” are the way the fibers go
Innermost is the same as internal in direction (opposite of external)

Subcostal muscles: span a rib or two and go from rib to rib
Transversus thoracis muscles: originate on sternum and radiate outwards to connect with ribs


External Intercostal

Superior attachment: Inferior margin of rib above

Inferior attachment: Superior margin of rib below

Innervation: Intercostal nerves; T1-T11

Function: Most active during inspiration; supports intercostal space; moves ribs superiorly


Internal Intercostal

Superior Attachment: Lateral edge of costal groove of rib above

Inferior Attachment: Superior margin of rib below deep to the attachment of the related external intercostal

Innervation: Intercostal nerves; T1-T11

Function: Most active during expiration; supports intercostal space; moves ribs inferiorly


Innermost Intercostal

Superior Attachment: Medial edge of costal groove of rib above

Inferior Attachment: Internal aspect of superior margin of rib below

Innervation: Intercostal nerves; T1-T11

Function: Acts with internal intercostal muscles



Superior Attachment: Internal surface (near angle) of lower ribs

Inferior Attachment: Internal surface of second or third rib below

Innervation: Related intercostal nerves

Function: May depress ribs


Transversus Thoracis

Superior Attachment: Inferior margins and internal surfaces of costal cartilages of second to sixth ribs

Inferior Attachment: Inferior aspect of deep surface of body of sternum, xiphoid process and costal cartilages ribs IV-VII

Innervation: Related intercostal nerves

Function: Depresses costal cartilages


Thoracic Wall Vasculature

Needs O2 and removal of metabolic waste
Large vessel = aorta, coming from arch is brachiocephalic trunk, common carotid, and subclavian

Subclavian branches: one travels on the sides of the breast bone in the inferior direction = internal thoracic and then split into terminal branches muscular phrenic and the superior epigastric artery in the abdomen (bifurcates at C7 ish)

Internal thoracic also includes the anterior intercoastal arteries that branch off the ribs
Posterior intercostals that come off the thoracic aorta
Anastomatic connection: laceration of any of the arteries, need to make sure to ligate the vessels


Azygos System of the Thoracic Wall

Arterial supply and venous drainage will be running parallel to each other
Anterior and posterior intercostal veins, internal thoracic veins= run parallel to counterparts

On the right side of the posterior thoracic cavity: large vein, azygos, that drains into the brachiocephalic vein

On left side: see two other vessels of the azygos system, top is accessory hemiazygos vein, which drains the left side of the thoracic cage, and the lower is the hemiazygos that drain the inferior aspect, but overall both branches drain into the azygos system

Right is all azygous and left side depends on if superior or inferior


Thoracic Wall Lymphatics

All lymph vessels in posterior thorax travel with intercostal arteries and veins that go to intercostal nodes (from the back… any lesions or infections in back go to these nodes)
Anterior will go to parasternal nodes

Eventually everything goes to thoracic duct which finally returns all the lymph flow from the body to the venous system


Thoracic Wall Innervation

Thoracic wall innervation all autonomic
Autonomic is responsible for innervation of chest wall
T1, dermatome 1, T2 dermatome 2… etc.
Nipple level T4
Xiphoid Process is T6
Umbilical/ belly button is T10


Thorax Dermatomes

Important landmarks associated with specific dermatomes:
T1 = forarm
T2 = humerus to section underneath clavicle to humerus
T4 = nipple
T6 = xiphoid process
T10 = umbilicus/ belly button
T12 = anterior superior iliac spine and ends at inguinal ligament
Only thing to remember is that there is a swoop down from the back and then level out in the chest area


Intercostal Nerves

Intercostal nerves coming out to back = ventral/anterior rami of spinal nerves T1-11 and lie in intercostal spaces between adjacent ribs

Largest branch = lateral cutaneous branch that pierces the lateral thoracic wall and divides into an anterior and posterior branch that innervate the overlying skin

In addition to these larger branches, when you get to front of the sternal margin there are small collateral branches

Intercostal nerves carry: somatic motor innervation of thoracic wall muscles (intercostal, subcostal, and transversus thoracis; somatic sensory innervation from the skin and parietal pleura; postglanglion sympathetic fibers to the periphery


Intercostal Space

Space between the ribs
Need to know relationship between the structures in the space; going to have vein, artery, and nerve= VAN in that order
Times in medical practice, whether needle insertion or cutting to get rid of fluid, infections, etc.. Don’t want to injure vessels, so you need to know where they are located



Inferior aspect of thoracic cavity
Structure responsible for our ability to breath
On ribs 11 and 12
Posteriorly is further down and moves upward as going to towards the anterior


Breathing Movements

Pump handle action or bucket
Pump handle: superior and anterior movement of sternum
Bucket: elevation of lateral shaft of ribs

Increases size and space of cavity
Humans are negative pressure breathers, and as pressure goes up we exhale



Pleura is a set of membranes, but the way they are arranged/fold they form a cavity
The fist is considered the lung, you get a layer around the fist and a layer that lines the chest wall, but one continuous membrane
The space in between is the cavity
Layer on surface of lung= visceral pleura, the layer lining the thoracic cage is the parietal layer, but in essence it is one layer
The space between them is the pleural cavity (one on L and R)


Viscera & Parietal Pleura

Visceral Pleura covers the lungs
Parietal Pleura covers the thoracic wall around the lung and consists of cervical, costal, diaphragmatic, and mediastinal pleura
Infections/trauma to pleural use the proper distinctions


Pleural Recesses

Provide: space for lungs to expand (lung fits in certain space, the lung will fill up empty space in back when breathing), but also provides a space for infection to thrive or fluid to accumulate = compromise respiration

Costodiaphargmatic recess- large space that provides lungs all the space it needs to dive down and also number 1 location for accumulation of fluid

When you insert a chest tube, or thoracocentesis procedure, you need to know where to put it

Costomedialstinal recess also allows for breathing; is located above the costodiaphragmatic recess



Right lung has three lobes and left has two lobes
Mediastinal aspect of the heart: pulmonary artery, which is superior to pulmonary veins (oxygenated)
Left and right lungs are ANATOMICALLY DIFFERENT
Root of the lungs goes around the bronchi
Hilum goes around root of the lung covering all the structural opening (arteries, veins, bronchi, etc. within the lung)
Pulmonary Artery: blood flowing into the lungs because no O2
Pulmonary Veins: blood flowing out of the lungs because oxygenated


Left Lung Anatomy: General

Two lobes: superior and inferior
Oblique fissure= only fissure of left lung that separates inferior and superior lobes
In superior lobe there is a cardiac notch for the heart
Lingula: tongue like projection which wraps around the heart; bottom of the lung
How can we tell where lung is divided? Contour rib 6 trace from front to back = oblique fissure dividing superior and inferior lobes
Important to know because need to auscultate each lobe of the lung because can have pathologies isolated to only one lobe


Left Lung Anatomy: Vessels

Depressions in lungs for vessels: aorta and aortic arch
Left subclavian wraps around apex and left brachiochepatlic does the same
REMEMBER: apex of lung will rise above the superior thoracic aperture so actually in neck because the aperture is the border of the thoracic cavity


Right Lung Anatomy

Three lobes: superior, middle, and inferior
Two fissures: oblique (separates inferior from superior lobe) and horizontal (superior separated from middle lobe)
No unique surface features like left lung

Surface depressions for venous vessels:
Inferior and superior vena cava, azygous system, and esophagus
Has subclavian vein and artery like left lung, which wrap around apex of both lungs
Right lung is vena cava and azygous and left lung for aorta


Surface Anatomy Reference for Lungs

Right Lung Lobes: superior, middle, inferior

Horizontal fissure: separates superior and middle lobes @ the level of the 4th intercostal space
Oblique fissure: separates middle and inferior lobes @ the level of the 5th intercostal space and contours rib #6

Use 6th rib as guide and 4th intercostal space for guide as well
How far back and down the spaces go: T12 is the tenant of the costodiaphragmatic recess; lower lung is T10 vertebral body
When listening to patients chest place stethoscope on back as well


Trachea: Location and Strucure

Trachea Location: extends from cervical vertebra level 6 to thoracic vertebral level 4 or 5 then bifurcates in to right and left main bronchus (not equal)
Esophagus located posterior to trachea

Structure: C-shaped cartilage rings, posterior wall primarily smooth muscle

Carina marks the bifurcation of the trachea
Right: splits into three and left splits into two


Trachea: Bronchial Tree and Bifurcation Pattern

Bronchial Tree:

Bifurcation Pattern:
Right main bronchus = wider and takes more vertical path (foreign bodies are most likely to be trapped here/path of least resistance)
Left main bronchus = narrower and takes more horizontal path

Main bronchus divides into lobar bronchi (secondary bronchi)- supplies each lobe

Lobar bronchus (secondary) divides into segmental bronchi (tertiary bronchi) - supplies each bronchopulmonary segment



scope down windpipe carina marks the bifurcation of the trachea
continue to branch off into secondary, tertiary, etc.


Bronchopulmonary Segments

Bronchopulmonary Segments = 10 per lung

Why is this important clinically?
Each color are unique component of the lung: smallest functional area that you can resect in surgery because they have a unique vasculature and innervation
Bronchopulmonary segment: smallest functional unit of the lung
If a patient has a lung tumor these are the smallest sections that can be resected


Vasculature: Pulmonary Arteries

Pulmonary Arteries: originate from the pulmonary trunk (right ventricle), which bifurcates ~ T4-T5 (anterior/inferior to bronchus); contains deoxygenated blood
Right pulmonary artery: longer than left, posterior to the ascending aorta, superior vena cava and upper right pulmonary vein, anterior to right main bronchus

Left pulmonary artery: shorter than right, anterior to descending aorta and left main bronchus, posterior to superiorpulmonary vein

Right bronchial artery and left is branch from aorta= supply that nourishes bronchial supply itself


Vasculature: Pulmonary Veins

Pulmonary Veins: each side contain two pulmonary veins: superior pulmonary vein and inferior pulmonary vein, which carry oxygenated blood to left atrium

Pulmonary circulation is isolated from the lungs circulation

Azygos venous system on right
When it gets to left atrium/ventricle goes from 100% to 97% from bronchial veins returning deO2 blood into the pulmonary vein


Pulmonary Vasculature

Pulmonary Vasculature:
- Bronchi and pulmonary arteries pair and branch in unison
- Pulmonary veins arise from pulmonary capillaries and drain toward and then course within the septa between adjacent segments

Avelous allows for CO2/O2 exchange and venule to veins to heart


Bronchial Arteries and Veins

Bronchial Arteries and Veins:
- Nutritive vascular system of the pulmonary tissue.
- Originate from thoracic aorta or one of its branches.
- Travel on the posterior surface of the bronchus

Right Bronchial artery: originates (usually) from 3rd posterior intercoatal artery
Left Bronchial arteries (2): originates from aorta

Bronchal Veins: drain to either the pulmonary veins or left atrium
Ayzgos venous system


Pulmonary Innervation

GVA and GVE via the anterior and (mainly) posterior pulmonary plexus
- Vagus nerve = parasympathetic – constrict bronchioles
- Sympathetic chain = sympathetic – dilate bronchioles

Branches of the pulmonary plexus accompany the bronchi and arteries within the lung.
Sympathetics T1-T5
Parasympathetics supply to thoracic cavity: vagus nerve CNX to the lungs

Left vagus provides branches and all form a plexus meshwork= sympathetic and parasympathetic that travel to targets


Lymphatic Drainage of the Lungs

Lungs drain to tracheobronchail nodes then to bronchomediastinal trunks.
Nodes associated with lungs are named for their location.
Pulmonary = located along lobar bronchi
Bronchopulmonary = hilum of the lung (drain from superficial lymphatic plexus)
Inferior Tracheobronchial (Carinal nodes)
Superior tracheobronchial

Drainage Pattern:
Right Lung – right side
Left superior lobe – left side
Left inferior lobe – right side (via inferior tracheobronchial/carinal nodes)


Lung Sounds: Anterior

Need to auscultate each section of the lung itself- need to know where to place the stethoscope

Apex of lung: superior to clavicle
Superior lobe of right lung: superior to pecs/ 3rd intercostal space below 2nd rib
Middle lobe of right lung: nipple of pec/5th intercostal space below 4th rib; stay medial
Inferior lobe of right lung: 7th intercostal space below 6th rib


Lung Sounds: Posterior

Apex of Left Lung: on 2rd intercostal space below rib 1
Superior Lobe of Left Lung: 4th intercostal space below the 3rd rib
Inferior Lobe of Left Lung: 7th intercostal space below the 6th rib


Pneumo, Hydro, and Hemo Thorax

Pneumo: air
Hydro: water
Hemo: blood
Things we don’t want in the pleural spaces
Penetrative trauma = pneumothorax
Water through infection = hydrothorax
Pleural need negative pressure and if we introduce these materials into the space it ruins this pressure and causes inability to breath


Examples of Hemothorax and Pneumothorax

Right hemothorax: can tell because the L lung field is open with sharp costodiaphargmatic recess
R: missing all the bottom space and fluids are white/gray

Clear black lung field on R side, and L lung field; heart is shifted to the left and the contents of the mediastinum is shifted to the left as well because so much pressure on right lung that everything is shifting to the left

Trauma to thoracic: every time the patient breaths in, the air can’t come out during exhalation so air is trapped= life threatening



Large gauge needle to release air to lower pressure
Also allows for lung to inflate

Throacocentesis: insert needle into pleural cavity; aim for center of intercostal space and upwards
Chest tube insertion: 7th intercoastal midaxiallary line because if you don’t you could pierce the liver and damage diaphragm
Want to go as low as possible because of gravity of fluid to get all of it out