Download 1 Anatomy – Thorax

Anatomy – Thorax
CXR
Bony structures Scapulae, Clavicles, 1st rib to 12th rib, 1st thoracic vertebra to 4th thoracic vertebra
Soft tissues Breast shadows, Soft tissues root neck, Left and right hemidiaphragm, Gastric bubble
Lungs Trachea, carina, Apex, Hilum, Costophrenic angles, Right horizontal fissure, L/R bronchus
Heart Right border – right atrium
Base – Right ventricle
Apex and left border – left ventricle/auricle, right atrium
Aortic root, Cardiothoracic ratio
SVC, RA, RV, LA, LV
Body wall
Venous return Anastomosing network radiating from umbilicus
Nerve supply
T2 – infraclavicular region, T4/5 – nipple
T10/11 – umbilicus, L1 – suprapub/inguinal
Chest wall – skin/subcut, ext/int/innermost intercostal, par pleura
Intercostal vessels run under rib between mid/innermost intercostals
Neurovasc bundle sup→inf: vein, artery, nerve
Thoracic inlet
T4-5 level (sternal angle)
Carina, division pulmonary trunk, transverse fissure Rt lung, pleura approaches midline anteriorly, hila of lungs
Reflection pericardium, SVC enters RA, asc Ao becomes arch, arch becomes desc Ao
Phrenic nerve, vagus nerve, L recurrent laryngeal nerve origin; Azygous vein, thoracic duct (crosses R to L)
Back Muscles
Superficial:
Trapezius
Course: nuchal line, ext occipital protuberance, ligamentum nuchae, vertebral spinous processes C7 - T12 -->
lat 1/3 clavicle, med acromion, upper scapular spine
Action: moves scapula, inc rotation
Latissimus Dorsi
Course: vert spines T7 down, post 1/3 iliac crest, lower 4 ribs, inf angle scapula, lumbar fascia -> floor intertub groove
Action: extends, retracts, adducts and med rotates arm
Deep: All nerve and artery = dorsal scapular
Rhomboid Major
Course: vertebral spines T2-5 --> med scapula
Action: retract, elevate and rotate scapula inferiorly
Rhomboid Minor
Course: inf ligamentum nuchae, vertebral spines C7 - T1 --> med scapula
Action: retract, elevate and rotate scapula inferiorly
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Levator Scapulae
Course: transverse processes of C1-4 --> upper med border scapula
Action: elevates and inferiorly rotates
Internal thoracic artery Supplies anterior body wall from
clavicle to umbilicus, from 1st part subclavian artery
Diaphragm
domed fibromuscular sheet separates thoracic/abdo cavities
Parts
Costal muscular, Crural (lumbar), Central tendinous
Arises from
Continuation fibres transversus abdominis
from costal margin
Posterior aspect of xiphisternum
Arcuate ligaments and crura
Fibres arch upwards into 2 domes and then descend to central
tendon at level of xiphisternal joint (T8)
Right dome ascends to 4th space in full insp; Left 5th
Ligaments
Crura
Right crus attached to antlat surfaces L1-3, Left crus L1-2
Fibres from medial edge each crus unite in front of aorta at level T12 to form median arcuate ligament
Medial arcuate ligament Thickening of psoas fascia → from side of body L1/2 into transverse process L1
Lateral arcuate ligament Thickening of ant layer lumbar fascia → from transverse process L1/2 into 12th rib
Central tendon Trefoil shaped – middle/left/right leaf , strongly attached to fibrous pericardium
Openings
Aortic
T12, Midline
Behind median arcuate ligament
Transmits Aorta, Azygous vein (on right), Thoracic duct (between artery and vein)
Oesophageal
T10, 2.5cm left of midline, Behind 7th costal cartilage
Transmits oesophagus, vagal trunks, oesoph branches left gastric artery, lymphatics, phreno-oesop lig
Vena caval
T8, right of midline, Behind 6th costal cartilage
Transmits IVC, Right phrenic nerve
Other structures Hemiazygous vein – left crus
Greater, lesser and least splanchnic nerves – each crus
Sympathetic trunk – behind medial arcuate ligament
Subcostal nerve and vessels – behind lateral arcuate ligament
Left phrenic – left dome
Nerve supply Left and right phrenic nerves – C3/4/5
Action Inspiration AP, transverse and vertical diameters all increase
Mediastinum
space between pleural cavities occupying centre of thoracic cavity containing heart, great vessels, oesophagus, trachea,
thymus, thoracic duct, lymph nodes, phrenic and vagus nerves
Superior mediastinum
wedge-shaped space between pleural cavities from thoracic inlet to sternal angle
Borders
Anterior Manubrium
Posterior border Bodies of T1-4
Inferior border Angle of Louis
Apex Thoracic inlet – level of T1
Contents
Arch of aorta at level T4 (angle of Louis)
Branches
Brachiocephalic trunk → right common carotid/right subcl
Left common carotid artery
Left subclavian artery arise just behind left common carotid
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Brachiocephalic veins
Formed behind SC joints by IJ and subclavian veins , In front of first part of subclavian artery
SVC, Trachea, Phrenic
Vagus nerve → right and left vagus → right or left recurrent laryngeal nerves
Oesophagus, Thoracic duct (duck between 2 gooses – ayzGOUS and oesophaGOUS)
Anterior mediastinum
potential space between pericardium and sternum
Contents - Thymus, Sternopericardial ligaments, Lymph nodes, Branches of the internal thoracic arteries
Middle mediastinum
Contents - Pericardium Fibrous, Serous, Great vessels, Lung roots, Phrenic nerves, Deep part of cardiac plexus
Posterior mediastinum
post to pericardium/upper surface diaphragm, continuous with space behind pretracheal and front of prevertebral fascia
Contents Oesophagus, Thoracic aorta, Azygous, hemiazygous and accessory hemiazygous veins, Lymph nodes
Thoracic duct lymph from lower half body plus L thorax, arm, head and neck
Lies ant to T5-12. Origin cisternae chyle in abdo. Travels Rt of thoracic Ao/Lt of azygous vein/post to oesoph
At T4 crosses to Lt to union of IJV and subclavian
Heart
Right border Right atrium; Left border Left ventricle, Auricle left atrium
Inferior border Right ventricle, Small portion of left ventricle
Inferior surface One third right ventricle, Two thirds left ventricle
Anterior/sternocostal surface Right ventricle/atrium, narrow strip L vent
Posterior surface Left atrium (and 4 pulmonary veins)
Surface markings
Right border R 3rd costal cartilage to lower border right 6th cartilage
Inferior border 6th costal cartilage to apex left 5th intercostal space in MCL
Left border Apex to lower border left 2nd costal cartilage 2cm from sternal margin
Valves tricuspid, mitral, aortic, pulmonary (cusps/chordae tendinae/pap musc)
M – 5LICS/T – 4LICS/ P – 3LICS/A – 3 RICS
SA – junction SVC/RA
AV – near opening coronary sinus
Supply of conducting system
SA node – RCA 60%, circumflex 40%
AV node/bundle – RCA AV nodal artery
R/L bundles ant IVA (LAD)
RCA → 60% SA, 80% AV, RA, most RV, post 1/3 septum
Descending thoracic aorta
Branches – Post intercostal (9 pairs), Oesophageal, Bronchial
Pleura and lungs
thin membrane fibrous tissue surfaced by single layer flat cells that clothes each lung
and lines pleural cavity
Parietal pleura
Arterial Intercostal, Int thoracic, Musculophrenic; Venous Azygous vein; Nerve Intercostal nerves, Phrenic nerve
Visceral pleura Arterial/venous bronchial vessels, No sensory
Surface markings pleura
3cm above clavicle, comes together T2
Diverges T4 left/T6 right
MCL T8, MAL T10, 12th rib T12
Lung edge 2 ribs higher
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Lungs
Left pulmonary artery over top left main bronchus
Right pulmonary artery Passes below carina ant to oesoph, Anterior to right bronchus at root
(RALS – Right artery Ant, Left artery Sup)
Oblique fissures; Right horizontal fissure Level 4th costal
cartilage
Lobes Each main bronchus → lobar bronchus → segmental
bronchi → 10 broncho-pulmonary segments
Left lung Upper lobe, Lower lobe (+lingula)
Oblique fissure
Right lung Upper lobe, Middle lobe, Lower lobe
Horizontal and oblique fissures
Bronchial blood supply
Arterial 2 left bronchial arteries from aorta, Right
bronchial artery from right post intercostal artery
Venous Bronchial veins – superf veins drain
azygous vein on rt and hemiazygous vein on lt
Lymph drainage Hilar nodes → tracheobronchial nodes;
Nerve supply Thoracic vagus and sympathetic chain
Oesophagus
Inferior margin cricoid C6 to oesophageal hiatus T10
Travels posterior to arch Ao (to Rt initially then post to desc Ao)
Supplied by recurrent laryngeal
Vagus Nerve
Jugular foramen → carotid sheath → mediastinum behind SC joints
Right: enters thorax anterior to R subclavian A, Rt side trachea, post
to R brachioceph/SVC/root of lung
Left: enters posterior to L common carotid A/ant to L subclavian A, at arch Ao gives off L recurrent laryngeal, pass post to
root L lung
Phrenic Nerve
Ventral rami C3-5
Arises between scal ant and med, runs on scal ant, over ant dome pleura, enters thorax between subclavian A and V.
Desc ant to hila, Rt pierce diaphragm at IVC opening, Lt to left of heart
Motor to diaphragm, sensory to pericardial/diaphragmatic/mediastinal pleura, diaphragm peritoneum (referred to C4
shoulder tip)
Phrenic travels lateral to vagus
Azygous vein
Collateral between SVC/IVC
Drains post wall thorax/abdo
Ascends Rt of vertebrae, arch over root right lung, join SVC
Hemiazygous
Origin L subcostal and asc lumbar veins
Ascends post to thor Ao to T9 then crosses to Rt (post to Ao/thoracic duct/oesophagus) to join azygous
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