Thorax Flashcards
Ribs articulation
I to VII articulate with sternum, VIII to X articulate with costal cartilage above them. XI and XII are floating ribs
Superior thoracic aperture borders
TI vertebrae posteriorly, rib I margin and manubrium anteriorly
Superior margin of manubrium level
Sternal angle level
same horizontal plane as intervertebral disc between TII and TIII.
intervertebral disc between TIV and TV.
Borders of axillary inlet
Superior margin of scapula posteriorly
Clavicle anteriorly
Lateral margin of rib I medially.
Apex of inlet is directed laterally and formed by medial margin of coracoid process.
Structures passing through diaphragm
IVC - central tendon of diaphragm at T8
Oesophagus - muscular part exiting left of midline at T10
Aorta - posterior to diaphragm at T12
Vagus nerve passes with oesophagus
Thoracic duct passes behind with aorta
azygos and hemiazygos veins also pass through aortic hiatus or through crura of diaphragm
Vertebrae level T4 and T5
Sternal angle
separate superior and inferior mediastinum
marks where arch of aorta begins and ends
passes through the site where SVC penentrates pericardium to enter the heart
Level where trachea bifurcates
Marks superior limit of pulmonary trunk
Left brachiocephalic vein
crosses midline immediately posterior to manubrium and delivers blood from left head and neck, left upper limb and part of left thoracic into SVC
hemiazygos veins
drain posterior and lateral left thoracic wall, and drains into azygos vein on the right side.
Breast anatomical location
From rib II to VI. Lies on deep fascia but has retromammary space (loose connective tissue) in between
Breast arterial supply
From axillary artery - superior thoracic, thoraco-acromial, lateral thoracic and subscapular
From internal thoracic arteries
From intercostal arteries - 2nd to 4th
Breast innervation
Anterior and lateral cutaneous branches of 2nd to 6th intercostal nerves, nipple supplied by 4th
Breast lymphatic drainage
75% axillary nodes
Most of the remaining into parasternal nodes deep to anterior thoracic wall and associated with internal thoracic artery
Some may occur via lateral branches of posterior intercostal arteries and connect with intercostal nodes
Drainage of axillary nodes
Into subclavian trunks
Drainage of parasternal nodes
Into bronchomediastinal trunks
Drainage of intercostal nodes
Either thoracic duct or into bronchomediastinal trunks
Mastectomy nerve damage
Risk of damage to long thoracic nerve (Serratus anterior) and thoracodorsal (latissimus dorsi)
Pectoralis major
Origin: medial half of clavicle and anterior surface of sternum, first 7 costal cartilages
Insertion: lateral lip of intertubular sulcus of humerus
Innervation: medial and lateral pectoral nerves
Function - adduction, flex and medially rotate arms
Pectoralis minor
Origin: anterior surface of 3 4 5 ribs
Insertion: coracoid process of scapula
Innervation: medial pectoral nerves
Function: depresses tip of shoulder, protracts scapula
Subclavius
Origin - rib I at junction between rib and costal cartilage
Insertion - interior surface of middle third of clavicle
Innervation - nerve to subclavius
Function - pulls clavicle medially to stabilise sternoclavicular joint, depresses tip of shoulder
Pectoral muscles
Pectoralis major, pectoralis minor and subclavius
Manubriosternal joint
Symphysis
Rib I and manubrium joint
Fibrocartilagious joint other articulation of ribs and sternum is synovial
Internal thoracic artery
paired artery, running on each side of the sternum, about 1cm from the sides of sternum.
branch of subclavian artery and descends posterior to costal cartilage of upper six ribs and lateral to sternum.
runs deep to external oblique, but superficial to vagus nerve.
Divides into musculophrenic artery and superior epigastric artery
Anterior intercostal artery
supply first six ribs, as branches of internal thoracic artery
Musculophrenic artery
Supplies the lower spaces of the ribs
Venous drainage of thorax
Anterior intercostal veins drain into azygos system or internal thoracic vein which drain into brachiocephalic vein.
Upper posterior intercostal veins form left/right superior intercostal veins. left side drain into left brachiocephalic vein, right side drain into azygos vein.
Supreme intercostal artery
upper two posterior intercostal arteries on each side, branch of costocervical trunk which is a branch of subclavian artery
Thoracic wall lymphatic drainage
Mainly to parasternal nodes, intercostal nodes and diaphragmatic nodes.
Superficial regions of thoracic wall drain mainly into axillary lymph nodes
Intercostal nerves carry
motor to muscles of thoracic wall
sensory from skin and parietal pleura
Postganglionic sympathetic fibers to the periphery
lower ones also supply muscles, skin and peritoneum of abdominal wall
Arterial supply to diaphragm
From above, pericardiophrenic and musculophrenic which are branches of internal thoracic artery.
Superior phrenic arteries from lower parts of thoracic aorta
largest arteries supplying diaphragm arise from below it - inferior phrenic artery which is branch of abdominal aorta.
Each lung hilum contains
1 pulmonary artery (superior)
2 pulmonary veins (inferior)
bronchi (posterior)
nerves, bronchial vessels and lymphatics
medial surface of right lung
SVC, IVC, azygos vein, heart and oesophagus
medial surface of left lung
thoracic aorta, aortic arch, heart and oesophagus
Trachea level
from C6 to T4/5
Right pulmonary artery position (longer than left)
Anterior to trachea and right main bronchus
Posterior to ascending aorta, SVC and upper right pulmonary vein
Left pulmonary artery position (shorter than right)
Anterior to left main bronchus and descending aorta
Posterior to superior pulmonary vein
transverse pericardial sinus
separates arteries and veins
oblique pericardial sinus
hand placed under apex of heart and moved superiorly slips into oblique sinus
source of somatic sensation (pain) from parietal pericardium is carried by somatic afferent fibres in the phrenic nerves - that’s why there is referred pain
nil
nerves supplying pericardium
vagus nerves, sympathetic trunks and phrenic nerves
venous drainage of diaphragm
brachiocephalic veins in neck
Azygos system of veins
abdominal veins (left suprarenal and IVC)
coronary sulcus circles the heart and separates atria and ventricles. What are its contents?
Right coronary artery, circumflex branch of LCA, small cardiac vein and coronary sinus
anterior interventricular sulcus contents
anterior interventricular branch of LCA, great cardiac vein
posterior interventricular sulcus contents
posterior interventricular artery branch of RCA< middle cardiac vein
Branches of RCA
Atrial branch - sinu atrial node
Marginal branch - along inferior surface of heart
Posterior interventricular branch
RCA supplies
Right atrium, right ventricle, SAN, AVN, interatrial septum and portion of left atrium, posteroinferior one third of interventricular septum and portion of posterior part of left atrium
LCA branches
anterior interventricular branch (LADA)
circumflex branch
LCA supplies
most of the left atrium and left ventricle, and most of the interventricular septum.
Cardiac plexus - superficial part
Between aortic arch and pulmonary trunk
Cardiac plexus - deep part
between aortic arch and tracheal bifurcation
Right pulmonary artery passes
posteriorly to ascending aorta and SVC
Left pulmonary artery passes
inferiorly to aortic arch, anterior to descending aorta
contents of superior mediastinum
thymus right and left brachiocephalic veins left superior intercostal vein SVC aortic arch with its three large branches trachea oesophagus phrenic nerves vagus nerves left recurrent laryngeal branch of vagus nerves thoracic duct
thymus
most anterior component of superior mediastinum
upper extent can reach into neck as high as thyroid gland, lower portion typically extends into anterior mediastinum over pericardial sac
arteries - typically small branches from internal thoracic arteries.
venous - left brachiocephalic veins and possibly into internal thoracic veins
developed from third pharyngeal pouch.
right brachiocephalic vein
begins posterior to medial end of right clavicle.
tributaries - vertebral, first posterior intercostal vein, internal thoracic veins. inferior thyroid and thymic veins may drain into it too
left brachiocephalic vein
begins posterior to medial end of left clavicle. joins with RBV to form SVC posterior to lower edge of right first costal cartilage close to right sternal border.
Crosses midline posterior to manubrium in adults, but in infants and children rises above superior border of manubrium hence is less protected.
SVC
starts at posterior to lower edge of right first costal cartilage and terminates at lower edge of right third costal cartilage
Lower half within pericardial sac hence contained in middle mediastinum
SVC receives azygos vein immediately before entering pericardial sac
arch of aorta
only part in superior mediastinum (descending aorta and ascending aorta are not)
all 3 branches of arch of aorta are posterior to LBV
brachiocephalic trunk
branches out of arch of aorta behind manubrium,
splits into right common carotid artery and right subclavian artery near right sternoclavicular joint
occasionally has thyroid ima artery which contributes to thyroid gland
left common carotid artery
ascends through superior mediastinum to left of trachea
ligamentum arteriosum
is also in superior mediastinum. was ductus arteriosus allowing blood to bypass lungs during development
aorta has 3 fixed point of attachment more likely to tear in deceleration injury
at aortic valve
ligamentum arteriosum
and where it passes behind median arcuate ligament of diaphragm to enter abdomen
right vagus nerve
lies between RBV and brachiocephalic trunk
descends in posterior direction toward trachea, crosses lateral surface of trachea and passes posteriorly to the root of the right lung to reach oesophagus. Just before oesophagus, crossed by arch of azygos vein.
left vagus nerve
posterior to LBV and between left common carotid and left subclavian.
Lies deep to mediastinal part of parietal pleura and crosses to left side of aortic arch. Continues to descend posteriorly and passes posterior to root of left lung to reach oesophagus.
Left recurrent laryngeal nerve
Arises from left vagus nerve at inferior margin of aortic arch just lateral to ligamentum arteriosum. passes inferior to aortic arch before rising on its medial surface. between trachea and oesophagus to terminate in larynx
Phrenic nerve innervates
Somatic afferent fibers to mediastinal pleura, fibrous pericardium and parietal layer of serous pericardium
right phrenic nerve
enters superior mediastinum lateral to right vagus nerve and lateral and slightly posterior to beginning of RBV. Continues inferiorly along right side of RBV and right side of SVC.
Descends along right side of pericardial sac, within fibrous pericardium, anterior to root of right lung. Leaves thorax by passing through diaphragm with IVC.
Left phrenic nerve
lateral to left vagus nerve and lateral and slightly posterior to beginning of left brachiocephalic vein, continues to descend lateral surface of aortic arch, passing superficially to left vagus nerve and left superior intercostal vein.
Follows left side of pericardial sac, within fibrous pericardium anterior to root of left lung, leaves thorax by piercing diaphragm near apex of heart.
right recurrent laryngeal nerve
hooks around right subclavian artery as it passes over cervical pleura.
Structures in posterior mediastinum
oesophagus and associated nerve plexus thoracic aorta and its branches azygos system of veins thoracic duct and associated lymph nodes sympathetic trunks thoracic splanchnic nerves
oesophagus
starts at C6 (inferior border of cricoid cartilage, ends at T11.
initially right of thoracic aorta then crosses anteriorly to the left of it.
Secured superiorly by attachment to pharynx and inferiorly by attchment to diaphragm
thoracic duct is right side inferiorly, but crosses to left more superiorly.
oesophagus compressed at 4 points
Junction of oesophagus with pharynx in neck
where it is crossed by aortic arch
where it is compressed by left main bronchus
at the oesophageal hiatus in diaphragm
oesophagus arterial supply
Arise from thoracic aorta, bronchial arteries and ascending branches of left gastric artery in abdomen
oesophagus innervation
arise from vagus nerves and sympathetic trunks.
Striated muscle in upper portion - branchial arches
Smooth muscle fibers - parasympathetic system, visceral efferents from vagus nerves. Preganglionic fibres synapse in myenteric and submucosal plexus of enteric nervous system in oesophageal wall.
visceral afferents of vagus - normal physiological process and reflex activity. No pain
visceral afferents of sympathetic trunks and splanchnic nerves - detection of oesophageal pain
oesophageal rupture
typically happens in lower third of oesopahgus due to sudden rise in intraluminal oesophageal pressure secondary due to uncoordination and failure of cricopharyngeus muscle to relax.
Tears typically occur on left hence often associated with large left pleural effusion.
branches of thoracic aorta
pericardial branches
bronchial branches
eosophageal branches - anastomotic connection include branches of inferior thyroid superiorly and branches of left inferior phrenic and left gastric arteries inferiorly
mediastinal branches
posterior intercostal - nine pairs usually lower 9 spaces (first 2 spaces by supreme intercostal artery usually a branch of costocervical trunk)
superior phrenic arteries - supply diaphragm anastomose with musculophrenic and pericardiophrenic artery
subcostal artery
azygos vein
starts opposite vertebra LI or LII at junction between right ascending lumbar vein and right subcostal vein.
azygos goes through aortic hiatus of diaphragm, or right crus of diaphragm. Ascends through posterior mediastinum usually to right of thoracic duct.
At T4, arches anteriorly over root of right lung to join SVC before SVC enters pericardial sac.
hemiazygos vein
starts at junction between left ascending lumbar vein and left subcostal vein. Usually enters thorax through left crus of diaphragm but may be through aortic hiatus. Ascends to approx T9, then crosses vertebral column posterior to thoracic aorta, oesophagus and thoracic duct to enter azygos vein.
Accessory hemiazygos vein
Descends from superior portion of posterior mediastinum to approx T8, then crosses vertebral column to join azygos.
Thoracic duct
Begins as a confluence of lymph trunks in abdo (cisterna chyli), which drains abdo viscera and walls, pelvis, perineum and lower limbs.
Extends from vertebra LII to root of the neck.
Enters thorax posterior to aorta through aortic hiatus, ascends to right of midline between thoracic aorta (on left) and azygos vein (on right). Lies posterior to oesophagus.
Moves across to the left at T5.
Joined by left jugular trunk and left subclavian trunk empties into junction of the left subclavian and left internal jugular veins.
Sympathetic trunk in thorax
T1-T5 supply thoracic viscera
T5-9 greater splanchnic nerves - ends in coeliac ganglion
T10-11 lesser splanchnic nerves - ends in aorticorenal ganglion
T12 least splanchnic nerves -end in renal plexus
Ribs articulation with thoracic vertebrae
Thoracic vertebrae has demifacet - superior to head of its own rib, inferior demifacet to head of lower rib
Facet at end of transverse process - tubercle of own rib
External intercostal muscles
Superior attachment - inferior margin of rib above
Inferior attachment - superior margin or rib below
Innervated by intercostal nerves T1 -T11
Active during inspiration, moves ribs superiorly
Internal intercostal muscles
Superior attachment - Lateral edge of costal groove of rib above
Inferior attachment - Superior margin of rib below
Innervated by intercostal nerves T1 -T11
Most active during expiration, moves ribs inferiorly
Innermost intercostal muscles
Superior attachment - medial edge of costal groove of rib above
Inferior attachment - internal aspect of superior margin of rib below
Innervated by intercostal nerves T1 -T11
Acts with internal intercostal muscles
