Anatomy: Thorax

Interchondral joints

"Articulation" between costal cartilages of lower ribs

Apex of heart

"tip" of the left ventricle, located in the 5th intercostal space

Left lung

-Made up of 2 lobes: superior and inferior -Separated by the oblique fissure -Lingua -Cardiac notch (5 superior branches, 5 inferior branches)

Function of the fibrous skeleton

-Provides attachments for myocardium of atria, ventricles, and cardiac valves -Provides electrical insulation between atria and ventricles

Mediastinum

-Region in the thoracic cavity between the R and L pleurae -Superior and inferior areas -3 regions: anterior, middle, posterior -Can be described in relation to the pericardium

Superior mediastinum

-Region in the thoracic cavity superior to the pericardium -Contains thymus (in kids), arch of aorta/great vessels, trachea, and esophagus

Pathway of intercostal nerves

12 thoracic spinal nerves exit the spinal intervertebral foramen Each nerve branches into anterior and posterior rami Anterior rami supplies the intercostal spaces Enter the intercostal space as a VAN bundle

Lymphatic drainage of breast

75% drain into axillary lymph nodes Remaining drain medially via parasternal lymph nodes

Accessory pattern

Abnormal pattern of ventilation Shrug shoulders while breathing, seen with COPD and other pulmonary diseases

Asymmetry

Abnormal pattern of ventilation that can imply trauma, pathology to one lung, pneumothorax, etc.

Inferior aperture

Allows the esophagus, IVC (inferior vena cava), and aorta to pass inferior to the abdominal cavity

Landmarks of PA CXR

Aortic arch, left ventricle, apex of heart, R/L diaphragm, R atrium, ascending aorta, tracheal shadow, right bronchi, R/L hilum, costodiaphragmatic recess

Point of maximal impulse (PMI)

Apical impulse

Posterior intercostal arteries

Arteries that supply the 3rd-11th intercostal spaces (Supply all of the 10th and 11th spaces)

Internal thoracic artery

Artery from which the anterior thoracic arteries branch off to supply the anterior 1st-9th intercostal spaces

Subcostal artery

Artery that supplies inferior to 12th rib

Sternocostal joints

Articulation between costal cartilage and sternum

Sternoclavicular (SC) joint

Articulation between sternum and clavicle

Posterior auscultation landmark

Auscultation alley

Trachea

Begins inferior to the larynx (cricoid cartilage), "C" shaped cartilage, the back is a membranous layer

Lobar bronchi

Bifurcation of the primary bronchi 2 on left and 3 on right

Bronchi

Bifurcation of the trachea at the sternal angle (carina), results in a right and left this

Landmarks of the sternal angle

Bifurcation of the trachea, beginning and end of aortic arch, can be palpated at the 2nd rib

Epicardium

Blends into visceral layer of serous pericardium

Branches of the aorta

Brachiocephalic trunk, left common carotid artery, left subclavian artery

Left marginal branch

Branch off the LCA Supplies the left ventricle

Anterior interventricular artery

Branch off the LCA Supplies the septum and left ventricle Also called the left anterior descending artery

Circumflex artery

Branch off the LCA Supplies the left atrium and ventricle

Nodal branches

Branches off the R coronary artery Supplies the SA/AV nodes

Right marginal branch

Branches off the R coronary artery Supplies the right ventricle

Posterior interventricular artery

Branches off the R coronary artery Supplies the right ventricle Also called the right posterior descending artery

Intersegmental bronchi

Branches off the segmental bronchi These continue to divide into 20-25 generations of smaller divisions

Segmental bronchi

Bronchi that supply the 10 bronchopulmonary segments

Myocardium

Cardiac muscle

Phrenic nerve

Comes from C3-5 Provides motor and sensory components of the diaphragm

Acinus

Composed of many respiratory bronchioles, alveolar ducts, and alveolar sacs

Superior aperture

Contains the esophagus, trachea, and the nerves and blood vessels that supply the head, neck, and upper extremity

Left coronary artery (LCA)

Coronary artery that branches into the anterior interventricular artery, circumflex artery, and the marginal branch

Right coronary artery

Coronary artery that branches into the nodal branches, marginal branches, and posterior interventricular artery

Branches of subclavian artery

Costocervical trunk, internal thoracic artery

Pressure gradient of the coronary arteries

Created from the aortic pressure backflow Occurs during early diastole of the cardiac cycle (isovolumetric relaxation)

Muscles of inspiration at rest

Diaphragm

Heart shadow distorted/widened

Difference in heart shadow between PA and AP views

Herpes Zoster (Shingles)

Dormant virus in single segmental nerve will become active Painful, red, vesicular lesion in dermatome pattern Common in thoracic region, but also seen in head/face and LE

Pericardium

Double walled, fibroserous sac lining the heart

Intercostal veins

Drain the intercostal spaces posteriorly to azygous system and anteriorly to internal thoracic veins

Azygous (unpaired) system

Drains the back and thoracoabdominal walls Consists of azygous, hemi-azygous, and accessory hemi-azygous veins

Muscles of expiration at rest

Elastic recoil of the lungs

Contents of the posterior mediastinum

Esophagus, descending (thoracic) aorta, thoracic duct, lymph nodes

Inspiration

External intercostals action

Transverse costal facets

Facets along the transverse processes of the thoracic vertebrae except the lower 2

Landmarks of left atrium

Foramen ovale, 4 openings of pulmonary veins, bicuspid (Mitral) valve

Fibrous skeleton

Four fibrous rings that surround the orifices of the valves

1/10 second, allows for atrial contraction

How long is the AV node delay and what is the purpose of it?

movement of thoracic wall: inspiration

Increase in AP and lateral diameter, "bucket handle" motion, increase superior to inferior length

Serous pericardium

Inside sac of the pericardium Invests the heart and is made up of two layers (parietal and visceral)

Expiration

Internal intercostals action

Muscles of expiration during exercise

Internal intercostals, abdominal muscles (rectus abdominis, int/ext obliques)

Contents of the anterior mediastinum

Internal thoracic vessels, fat, few lymph nodes

Intervertebral (IV) joints (of thoracic spine)

Joint made up of the discs and facets between vertebrae

Xiphosternal joint

Junction of xiphoid and sternum

Costodiaphragmatic recess

Large pleural recess located in the posterolateral region

Visceral pleura

Layer of the pleura that invests the lungs

Parietal pleura

Layer of the pleura that lines the thoracic wall and diaphragm

Levator costarum

Located external posterior attach to ribs and transverse process Inspiration elevate ribs

Subcostal muscles

Located on the internal posterior thoracic cage Inspiration elevate ribs

Serratus posterior inferior

Lower back muscles that depress the ribs during expiration

Bronchioles

Lower branches of the tracheobronchial tree where the cartilage begins to disappear

Right lung

Made up of 3 lobes: superior, middle, inferior which are separated by the oblique and horizontal fissures (3-superior, 2-middle, 5-inferior)

Diaphragm

Major muscle of inspiration There are sternal, costal, and lumbar regions Contraction flattens this and the pressure changes cause increase of air into the lungs

Structures of the sternum

Manubrium, sternal body, xiphoid process

Pulmonary (left) surface

Mostly left ventricle

Diaphragmatic (inferior) surface

Mostly left ventricle and partially right ventricle

Sternocostal (anterior) surface

Mostly right ventricle

Landmarks of a breast

Nipple (4th intercostal space), circular base (sternum to MAL, ribs 2-6)

Innermost intercostals

Not completely understood intercostal muscles, may elevate

Terminal bronchiole

One of the last branches before gas exchange occurs

Fibrous pericardium

Outer sac of the pericardium Attaches to diaphragm via pericardiacophrenic ligament Attaches to the sternum via sternopericardial ligament

Vertebral body costal facets

Pairs of inferior and superior facets on all thoracic vertebrae except the lower 4 (B and E in the picture)

Tubercle

Part of rib that articulates with the transverse process

Visceral layer of serous pericardium

Part of serous pericardium that blends with the epicardium

Head

Part of the rib that has facets that articulate with two vertebrae

Costal angle

Part of the rib that is a common site of rib fracture, weakest point

Parietal layer of serous pericardium

Part of the serous pericardium that blends with the fibrous pericardium

Branches of thoracic aorta

Posterior intercostal arteries, subcostal artery

Base of heart

Posterior side of the heart (as it sits in vivo) Formed by the left atrium (and some RA)

Pericardial cavity

Potential space between the parietal and visceral layers of serous pericardium Smooth serous fluid allows the heart to move freely in the pericardial sac

Parietal cavity

Potential space between the two pleural layers Lubricated by serous pleural fluid

Thoracentesis

Procedure to remove fluid from the pleural cavity Avoid damage to intercostal structures (VAN) and lung when inserting needle

Function of the thoracic wall

Protect thoracic content (heart, lungs, blood vessels, esophagus, etc)

Anterior auscultation landmarks

R/L 2nd ICS, Erb's point (L 3rd ICS), left sternal border (4th or 5th ICS), L 5th ICS (midclavicular)

Hemi-azygous and accessory hemi-azygous veins

Receive blood from left side 5th-12th intercostals

Coronary sinus

Receives blood from most of the cardiac veins Drains directly into the right atrium

Brachiocephalic vein

Receives blood from the left side 1-4 intercostal veins

Azygous vein

Receives blood from the right side intercostals and hemi-azygous and hemi-azygous accessory veins. Drains back to the heart via the superior vena cava

Anterior mediastinum

Region in thoracic cavity anterior to the pericardium

Posterior mediastinum

Region in thoracic cavity posterior to the pericardium

Superior vena cava (SVC)

Returns blood back to the RA from areas superior to the diaphragm (except the heart and lungs)

Inferior vena cava (IVC)

Returns blood back to the right atrium from areas inferior to the diaphragm

R/L Pulmonary veins

Returns oxygenated blood back to the left atrium from the lungs

Costochondral joints

Rib articulation with chondral cartilage

Costotransverse joint

Rib articulation with transverse process

Costovertebral joint

Rib articulation with vertebrae body (A in the picture)

Atypical ribs

Ribs 1,2, 10-12

True Ribs

Ribs 1-7, attach directly to sternum

Floating Ribs

Ribs 11-12, do not attach to the sternum

Typical ribs

Ribs 3-9

False Ribs

Ribs 8-10, attach indirectly to sternum

Bones of the thoracic wall

Ribs, thoracic vertebrae, sternum

Landmarks of right atrium

SVC/IVC openings, opening coronary sinus, fossa ovalis, tricuspid valve

Aorta

Sends blood to the body from the left ventricle

Pulmonary trunk

Sends unoxygenated blood from the right ventricle to the lungs

Inspiration (Radiology)

Should a CXR be taken during inspiration or expiration?

Hilum (Root)

Site where the lung becomes covered by visceral pleura.

Costomediastinal recess

Smaller pleural recesses located in the anterolateral region, posterolateral to sternum

Landmarks of thoracic vertebrae

Spinous process, transverse process, vertebral body costal facets, transverse costal facets

Bony landmarks of the posterior thorax

Spinous processes of thoracic vertebrae, costovertebral angle (CVA)

Landmarks of lateral CXR

Sternal angle, heart shadow, mediastinum, costophrenic recess, R/L diaphragm

Manubriosternal joint

Sternal angle, where the manubrium and body of sternum meet

Lingua

Structure that is similar to the middle lobe of the right lung

VAN

Superior->inferior: vein, artery, nerve Bundle that enters the intercostal space just inferior to the rib Second set of smaller collaterals located superior to each rib

Shaft

The thin, flat part of the rib

Endocardium

Thin, smooth lining layer of the heart walls

thoracic aorta, axillary artery, subclavian artery

Three major sources of circulation to the thoracic wall

Costocervical trunk

Trunk from which the superior thoracic arteries may branch off to supply the 1st two intercostal spaces (May branch off the axillary artery)

Serratus posterior superior

Upper back muscles that elevate the ribs during inspiration

Aortic valve

Valve between the L ventricle and aorta

Bicuspid valve

Valve between the LA and LV

Pulmonary valve

Valve between the R ventricle and pulmonary trunk

Tricuspid valve

Valve between the RA and RV Cusps are anchored by papillary muscles and chordae tendinae

Anterior axillary line

Vertical line along anterior axillary fold (formed by pec major)

Mid axillary line

Vertical line through apex of axilla (armpit)

Posterior axillary line

Vertical line through posterior axillary fold (formed by lat dorsi and teres major)

Posterior median (mid spinal or mid vertebral) line

Vertical line through spinous processes of vertebrae in mid-saggital plane

Anterior median (midsternal) line

Vertical line through sternum in mid-saggital plane

Scapular lines

Vertical lines that pass through inferior angles of the scapula, parallel to the posterior median line

Midclavicular lines (MCL)

Vertical through midpoints of clavicles, parallel to median line

anterior median and midclavicular lines

What are the anterior vertical lines?

anterior, mid, and posterior axillary lines

What are the lateral vertical lines?

posterior median and scapular lines

What are the posterior vertical lines?

Anterior cardiac vein and the smallest cardiac veins

What cardiac veins do NOT drain into the coronary sinus and empty directly into the RA?

Great, middle, small and the oblique vein of the LA

What cardiac veins drain into the coronary sinus?

Primary bronchus, pulmonary veins and artery, bronchial vessels, pulmonary nerves, lymph vessels

What does the hilum contain?

SA node -> AV node -> AV bundle (of His) -> L/R bundle branch -> Purkinje fibers

What is the conducting pathway of the heart?

Respiratory bronchiole

Where gas exchange begins

Along the right 2nd intercostal space

Where would you auscultate to hear the aortic valve?

Along the apex (left 5th intercostal space)

Where would you auscultate to hear the bicuspid valve?

Along the left 2nd intercostal space

Where would you auscultate to hear the pulmonary trunk?

Along left sternal border at the 5th (or 4th) intercostal space

Where would you auscultate to hear the tricuspid valve?

Landmarks of left ventricle

bicuspid (Mitral) valve, papillary muscle/chordae tendinae, aortic valve

Muscles of inspiration during exercise

diaphragm and external intercostals

Muscles of inspiration during extreme exercise

diaphragm, external intercostals, and accessory muscles (SCM, scalenes, and sometimes pecs)

Landmarks of typical ribs

head, neck, tubercle, shaft, costal angle

Bony landmarks of the anterior thorax

jugular (sternal) notch, sternal angle, 2nd rib, intercostal spaces (ICS), costal margin/angle, interspaces 2-6

Contents of the superior mediastinum

thymus (in kids), arch of aorta/great vessels, trachea, and esophagus

Landmarks of right ventricle

tricuspid valve, papillary muscle/chordae tendinae, pulmonary valve