Anatomy of the Thorax Flashcards
Boundaries of root of neck / superior thoracic aperture?
Anterior aspect of body of T1, medial part of rib 1, manubrium anteriorly
Boundaries of inferior thoracic aperture?
Posteriorly = Vertebral body of rib 12.
Lower border of rib 12 and distal end of rib 11, cartilaginous ends of ribs 7-10
Xiphoid process anteriorly
Relation of subclavian vessels and brachial plexus at root of neck?
Subclavian vessels and brachial plexus all pass over rib one and underneath the clavicle
Subclavian vein is most superficial, on top of scalenus anterior
Subclavian artery sits between scalenus anterior and medius
Brachial plexus sits behind artery at level of rib 1 - also between the scalenus muscles
Rough structure of the breast?
Why does malignancy cause pitting of the skin?
Series of ducts and secretory tubules
These converge to form 15-20 lactiferous ducts
This is surrounded by connective stromal tissue
Areas where this tissue thickens = suspensory ligaments
Suspensory ligaments are continuous with dermis of the skin. In malignancy they tighten = pitting of skin
Blood vessels, innervation and lymphatics of breast?
Arterial:
Lateral = branches of axillary artery = sub scapular, lateral thoracic, superior thoracic + thoraco-acromial
Medial = Via internal thoracic (also called int. mammary), which is branch of subclavian
Venous = parallels
Innervation = intercostal nerves 2-6, nipple = 4th intercostal
LN’s = Mainly axillary, some parasternal
3 Muscles of the pectoral region?
Pectoralis major = adducts, flexes and medially rotates humerus at shoulder
Origin. = Medial half of clavicle and sternum
Insertion = lateral lip of intertubercular sulcus
Lateral and medial pectoral nerves
Pectoralis minor = protracts scapula, depresses tip of shoulder
Origin = anterior surface of ribs 3-5
Insertion = coracoid process
Medial pectoral nerve
Subclavius = Pulls clavicle medial to stabilise SCJ
Origin = Rib 1
Insertion = Groove on inferior third of clavicle
Nerve to subclavius
Order of structures in intercostal groove?
Vein is most superior
Then artery
Then nerve most inferior
Intercostal groove is on inferior margin of ribs
Rib one articulation with vertebrae and grooves?
Only has one articular surface for body of T1
Superior surface has distinct scalene tubercle which separates two grooves:
- anterior = Subclavian vein
- Posterior = subclavian artery
Why is rib 10 special?
Has single facet for articulation with its own vertebra
What articulation occurs on manubrium?
Two oval facets for clavicles
Immediately inferior = large facet for rib 1
Lower end is Demi-facets for rib 2
Angle of Louis?
Landmark for 4 things….
Manubriosternal joint = T4/T5
Costal cartilage of 2nd ribs
Arch of aorta + tracheal bifurcation
Union of azygous and SVC
Crossing of thoracic duct over the midline
Sternal facets for articulation?
Superiorly = 2 demifacets for rib 2
Facets for rib 3-6
Inferiorly = demifacets for rib 7
Xiphoid process facets for articulation?
Demifacets for rib 7
What ligament is routinely divided in midline sternotomy?
What vessels must we be wary of?
Interclavicular ligament
Brachiocephalic vein, is posterior at superior aspect of sternotomy incision
What is cervical rib?
How many are bilateral?
Classic signs?
Elongation of the transverse process of C7 = fibrous band attaches to Rib 1
70% bilateral
Neurological deficit and compression of subclavian can cause radial pulse absence
Intercostal muscles? - function, origin, insertion + innervation
External intercostals = assist inspiration, elevate ribs
Origin = inferior aspect of rib above
Insertion = superior aspect of rib below
Intercostal nerves
Internal intercostals = assist expiration, depress ribs
- deep to the external intercostals
Origin = Lateral edge of intercostal groove above
Insertion = Superior margin of rib below
Intercostal nerve
Innermost intercostals = assist internal intercostals = expiration
Origin = medial edge of costal groove above
Insertion = internal aspect of superior margin below
Intercostal nerves
Arteries and veins to thoracic wall?
Arteries = anterior and posterior intercostal arteries
POSTERIOR:
- upper two originate from supreme intercostal artery = branch of costocervical trunk
- Other 9 pairs originate from directly from posterior aspect of aorta
ANTERIOR:
- All supplied in some way by internal thoracic (branch of subclavian)
- upper 6 supplied directly
- at 6th costal cartilage, the internal thoracic splits into Musculophrenic and superior epigastric artery
- so lower 6 anterior ones are supplied by Musculophrenic arteries
Venous mirrors this
What do the upper posterior intercostal veins form and then drain into?
Form the superior intercostal vein
On right drains into azygous
On left into brachiocephalic
Embryology of the diaphragm?
Formed due to progressive fusion of septum transverse, pleuroperitoneal folds and muscular ingrowth
Septum transversum = Central tendon
Pleuro. folds = parietal membranes
Cervical somites C5-7 = muscular components
Where does central tendon attach superiorly, and what is its continuation posteriorly?
Superiorly attaches to pericardium
Posteriorly it forms median arcuate ligament
Apertures of the diaphragm?
I ate ten eggs at 12
IVC = T8 - right phrenic nerve too Oesophagus = T10 - also have vagus here Aorta = T12 - also have thoracic duct here and azygous
Arterial supply of diaphragm?
Inferior and superior aspects
Superior = from pericardiophrenic and Musculophrenic = both branches of internal thoracic (subclavian)
Inferior = Superior phrenic from lower thoracic aorta directly + inferior phrenic from abdominal aorta
Diaphragmatic hernias?
Morgagni = right anterior, good prognosis, minimal disruption
Bochdalek = left posterior, scaphoid abdomen and pulmonary hypoplasia ± pulmonary HTN.
Poor prognosis and requires surgery
Which cell type lines the pleural cavity?
Mesothelial
What covers the parietal pleura of the lung superiorly?
Suprapleural membrane
Attaches laterally to medial part of first rib and transverse process of C7
at what level is the root of lung / pleural reflection?
T5-T7
Lobes and fissures of each lung?
Right = 3 lobes + oblique and transverse fissure Left = 2 lobes + oblique fissure
Inferior border of lungs?
6th rib MCL
8th rib MAL
10th rib posteriorly
What does the root of the lung contain, and its arrangement?
from the root, what is the inferior projection of the lung pleura called?
1 pulmonary artery
2 pulm. veins
1 main bronchus
Bronchial veins, arteries and nerves
Artery is superior
Veins inferior
Hilum posterior
Inferior to root of each lung, pleura projects inferiorly = pulmonary ligament
Right lung - arrangement of vessels etc medially?
Right:
Above hilum is azygous vein - feeds into SVC
Above this is groove for SVC and right innominate vein
Behind hilum is groove for oesophagus. Azygous sits posterior to this
Right bronchus = wider and straighter. = foreign body
Left:
Above hilum = furrow for aortic arch, superiorly = groove for left subclavian
Behind the hilum = vertical groove for descending aorta
Left main bronchus at T6
What level does the pulmonary trunk bifurcate?
Relations of left and right pulmonary arteries?
T4/5
Right has longer course crossing midline.
- Anteroinferior to tracheal bifurcation
- Passes posterior to right superior pulmonary vein, ascending aorta and SVC
Left:
Anteroinferior to tracheal bifurcation
Passes anterior to descending aorta
Posterior to superior pulmonary vein
Where does trachea start and what level is the tracheal bifurcation?
C6 - T4/T5
Tracheal relations in the neck vs thorax?
Neck:
Anterior = isthmus of thyroid, Sternohyoid and sternothyroid, cervical fascia and inferior thyroid veins + thyroid ima
Lateral = inferior thyroid arteries, common carotids and recurrent laryngeal
POSTERIOR =. OESOPHAGUS
Thorax:
Anterior = Manubrium
Aortic arch, left common carotids + deep cardiac plexus
Lateral - right = pleura and right vagus, left. = left recurrent nerve, aortic arch, left common carotids and subclavian arteries
Divisions of the mediastinum?
Superior = above transverse line from angle of Louis
Inferior is below this, further subdivided into…..
Anterior, middle = pericardium, posterior
Contents of each section of mediastinum?
Superior: SVC, brachiocephalic veins and arch of aorta Trachea, oesophagus and thymus thoracic duct Vagus, phrenic and recurrent laryngeal
Anterior = LN’s and fat
Middle = pericardium, heart, origin of great vessels, main bronchi + arch of azygous
Posteiror: azygous and thoracic aorta Oesophagus thoracic duct Vagus, splanchnic and sympathetic
Structure of pericardium?
Fibroserous sac
Fibrous layer = tough connective tissue
- base is on diaphragm = central tendon
- anteriorly connect to sternum via sternopericardial ligament
- Apex continues with adventitia of vessels
- Phrenic nerve passes via this fibrous layer.
Serous layer = inner parietal and visceral layers
- 2 reflections = oblique and transverse sinuses
Which nerve passes through fibrous part of pericardium?
Phrenic nerve, as do the pericardiophrenic vessels
Nerves and vessels of pericardium?
Arteries = internal thoracic, pericardiophrenic, Musculophrenic, and inferior phrenic
Veins enter azygous system
Nerve = phrenic. Referred pain to shoulder as C345
What are the two external sulci of the heart and what runs in them?
Coronary sulcus:
- Separates the atria from the ventricles
- RCA, small cardiac vein, coronary sinus and LCx
Posterior interventricular sulcus = middle cardiac vein, PI artery
Anterior inter ventricular sulcus = Great cardiac vein, AI artery
Where does the coronary sinus open into the RA?
Immediately medial to opening of SVC
How is right atrium divided?
From line between IVC AND SVC
this line is marked internally by crista terminalis, and externally by the sulcus terminalis cordis
Space posterior to crista = sinus of venae
Space anterior = atrium proper
What defines the atrium proper, and what are its walls covered in?
Anterior to crista terminalis = atrium proper
Atrium proper’s walls are covered in muscular ridges = pectinate muscles
What does the inflow portion of RV have?
What do these attach to and what do they prevent?
Trabeculae carnae / papillary muscles
Some attach to the Chorda tendinae which connect to free edge of cusps of tricuspid valves = prevent eversion of valve with high ventricular pressure
What is the outflow tract of the RV called?
Infundibulum / conus arteriosus
How many cusps does pulmonary valve have, and what structure do these have to cause closure?
Three semi-lunar cusps
Each has a pocket like structure = fills with bloods after ventricular contraction recoils. blood = closure
How does left atrial structure differ to right?
Contains musculi pectinate, BUT NOT CRISTA TERMINALIS
How do the trabeculae in LV differ to the ones in RV?
How do papillary muscles differ?
They are finer and more delicate .
Papillary muscles = larger
what location would metallic valves be on CXR?
R 3rd ICS = A
L 4th ICS = M
R 5th ICS = T
Where does coronary sinus and sit and where does it receive what veins from?
Sits in coronary sulcus
Great cardiac vein comes from anterior interventricular groove
Middle comes from posterior
Small cardiac vein drains into right atrium directly
What are the veins of Thesebius?
Small group of veins that drain directly into the RV and RA
Where does RCA originate and what does it supply?
Originates from right aortic sinus from ascending aorta
Descends vertically in coronary sulcus to the posterior inter ventricular sulcus
SA node in 60%, AV node in 80%
posterior third of interventricular septum
Right atrium
Lower part of RV
LCA - where it originates and what it supplies?
Originates from left aortic sinus of ascending aorta
Anterior 2/3rds of interventricular septum
other 40% of SA node
Most of LA and LV
part of RV
Location of deep and superficial cardiac plexus?
Deep sits posterior to ascending aorta and anterior to bifurcation of trachea
Superficial sits superior to bifurcation of pulmonary trunk and inferior to aortic arch
what gives parasympathetic supply to the heart?
Vagus
What level does the pulmonary trunk divide, and relations of right and left branch?
T5/T6
Right passes posterior to ascending aorta and SVC + superior pulmonary vein. Anterior and inferior to tracheal bifurcation
Left passes anterior to descending aorta, anterior and inferior to tracheal bifurcation.
Posterior to superior pulmonary vein
When does ascending aorta become aortic arch?
At second costal cartilage, where it enters superior mediastinum
Superior mediastinum borders?
Transverse plane above sternal angle, oblique plane from sternal notch to T1
Posterior sternum and anterior body of thoracic vertebrae
Contents of superior mediastinum?
TOT = trachea, oesophagus and thymus
Aortic arch, azygous vein, brachiocephalic trunk + SVC
Vagus, phrenic and recurrent laryngeal
Thoracic duct
Thymus - where does it sit in the superior mediastinum, arterial supply and venous drainage?
Cellular make up of thymus?
Most anterior component of superior mediastinum
Arterial = internal mammary or pericardiophrenic (from internal thoracic)
Venous = left brachiocephalic
Cortex is tightly packed lymphocytes. Medulla is epithelial cells, concentrically arranged around a keratinised centre = HASSALLs Corpuscle
Branches of aortic arch?
First = brachiocephalic trunk 2nd = L common carotid 3rd = L subclavian artery
What is anterior trachea or oesophagus?
Trachea = Towards the front Oesophagus = Out back
Vagus nerve: route of right vs left?
Right:
Enters sup. mediastinum between brachiocephalic trunk and vein
Crosses anterior to subclavian artery, at this point gives of recurrent laryngeal.
descending posterior to the trachea
Crosses lateral surface of trachea and passes posterior to the root of the right lung
Just before it reaches oesophagus it is crossed by azygous
Left:
Enters superior mediastinum posterior to left brachiocephalic vein, between the common carotid and subclavian artery
Crosses left side of aortic arch anteriorly. here it gives off recurrent laryngeal, just lateral to ligamentum arteriosum.
Descends posteriorly behind root of left lung
Both exit with the oesophagus at T10 In oesophageal hiatus
Phrenic nerve: Root of right vs left?
Both enter posterior mediastinum lateral to vagus, and posterior to subclavian vein / anterior to anterior scalene / subclavian artery.
Right:
Continues inferiorly along right side of brachiocephalic vein and SVC
Descends on right side of pericardial sac, in fibrous membrane
Anterior to root of lung
Leaves thorax passing through diaphragm at T8 with IVC
Left:
Descends across the left lateral aortic arch, SUPERFICIAL to the vagus
Enters fibrous layer of pericardium, and passes anterior to left lung root
Leaves thorax piercing diaphragm near apex of heart
Posterior mediastinum contents?
azygous and thoracic aorta
Oesophagus
thoracic duct
Vagus, splanchnic and sympathetic
Oesophagus: route and relations posterior and anterior?
As it approaches diaphragm it moves left and anterior
Anterior = Right pulmonary and left main bronchus
+ left atrium
Posterior = Thoracic duct - high up is on left, lower down on right. Thoracic aorta sits on its left hand side
4 narrowings of the oesophagus?
Border of pharynx
Aortic arch = superior mediastinum
Left main bronchus = posterior
Oesophageal hiatus = posterior
thoracic aorta boundaries?
Branches?
T4-T12
Paired = posterior intercostal and superior phrenic
Un paired = Bronchial, pericardial, oesophageal and mediastinal
When does subclavian artery become the axillary?
Branches of subclavian artery?
When it reaches lateral border of first rib
1st part = Vertebral, internal thoracic and thyrocervical
2nd part = Costocervical
3rd part = Dorsal scapular
What does thyrocervical artery arises from, and where?
From first part of subclavian, at inner border of scalenus anterior
How does brachiocephalic veins form?
How do these go on to form SVC?
Subclavian and internal jugular veins unite.
Right brachiocephalic Is posterior to medial clavicle and descends
Left brachiocephalic is posterior to medial clavicle, crosses over to the right and joins the right brachiocephalic.
What is the left superior intercostal vein formed of and where does it drain to?
Formed by 2/3/4 posterior intercostal veins
Passes over left side of aortic arch
Passes between the phrenic and vagus = medial to phrenic and lateral to vagus
Where does azygous vein join SVC?
Immediately before it enters right atrium
What are the key landmarks of the IVC?
Forms at L5 by merging of common iliac veins
L1-5 = lumbar veins join
L2 = right gonadal vein joins (left joins into the L renal vein)
L1 = supra-renal veins and renal veins join
T8 = Hepatic vein, inferior phrenic and pierces diaphragm
Is IVC to the right or left of midline?
Right
What forms the azygous vein?
Union of right ascending lumbar and right subcostal veins at L1/L2
How do thoracic duct and azygous vein enter thorax?
Both enter via the aortic hiatus
Azygous is on the right, thoracic duct on left
Does azygous vein pass anterior or posterior to right lung root?
Anterior, to join SVC
How is the semi-azygous vein formed and how does it enter thorax?
How far does it ascend?
How far does accessory nerve descend?
Via left ascending lumbar and left subcostal vein joining
Pierces diaphragm at left crus
T9
T8
Whats thoracic duct a continuation of?
Where does it enter thorax?
How is it related to oesophagus?
Cisterna chyli in abdomen
T12
Posterior to oesophagus on right, crosses to left at T5 (angle of Louis)
Where do left and right side of head and neck drain?
Left > subclavian and jugular . joins thoracic duct prior to inserting in left brachiocephalic vein
Right side > Subclavian and jugular trunks > right lymphatic duct. > mediastinal trunk > right brachiocephalic vein
Thoracic vertebrae poets of attachment for ribs?
three sites:
- Oval facet at ed of each transverse process articulates with tubercle of rib.
- x2 demifacets on inferior and superior vertebral body. Superior articulates with head of its own rib, inferior with that of rib below.
