Anatomy of the thorax Flashcards
Blood flow to areas of the heart
LAD: left atrium, ventricle and IVS
Left circumflex: Left atrium and left ventricle
Left marginal: Left ventricle
RCA: Right atrium and ventricle
Right circumflex: Right ventricle and apex
What are the deep muscular relations of the breast
Pec major and serratus anterior
The lower medial edge just overlaps the upper part of the rectus sheath
How many lobules does the breast tissue have
15-20 lobules within the breast, each extends into the lactiferous duct and they all converge to the nipple
The lactiferous sinus acts as a reservoir and it lies beneath the areola
What are the coopers ligaments
Fibrous septa which extend from the subcutaneous tissue to the fascia of the chest wall (the pectoralis fascia)
These are responsible for the peau d’orange. invasion of the axillary lymphatics by tumour causes obstruction and subsequent oedema of the overlying skin. Parts of the skin that are tethered to the coopers ligaments appear as dimples. Hence, giving the appearance of an orange peel
What is the blood supply to the breast
Internal thoracic which is a branch of the subclavian
lateral thoracic which is a branch of the 2nd part of the axillary artery
Thoracoacromial artery which is a branch of the 2nd part of the axillary artery
Intercostal artery
What is the sensory innervation of the breast
4th to 6th intercostal nerves provides sensory and autonomic innervation
Where should a subclavian line catheter tip be
In the SVC and above the pericardial reflection
Describe the anatomy of the neurovascular bundle
Superior to inferior it is VAN in the intercostal groove
What is the superior limit of the pleura
The pleura projects 2.5cm above the middle third of the clavicle
What is the role of the thymus
important for the maturation of T cells and also releases hormones involved in T cell proliferation.
It atrophies after puberty
What ribs are considered atypical
1,2,10,11,12
The first is short and wide and has a single facet and the scalene tubercle
The second is thinner and longer and has a tuberosity on its upper surface for attachment with the serratus anterior
The 10th has only a single facet
11 and 12 also have single facets with no neck
What is the lymph drainage of the breast
What are the surface markings of the heart
Inf: 5th intercostal space midclavicular line on the left to the 6th costal cartilage on the right
Sup: 3rd costal cartilage on the right to the second intercostal space 2cm on the left of the sternum
What chambers of the heart form its boundaries
How many layers does the pericardium have
3 layers
Outer fibrous
Inner serous parietal and visceral layers
Where do the LCA and RCA arise from
From the aortic sinuses, there are 3
the LCA comes from the left and the left posterior AS
the RCA comes from the right coronary sinus
What is the venous drainage of the heart
Great, middle and small cardiac veins as well as the oblique and posterior veins. This forms 2/3rd of the venous drainage
The remaining 1/3rd is from venae cordis minimae and drain into each individual chamber.
The coronary sinus opens on the inferior border of the right atrium between the IVC and the tricuspid valve
What is the anatomically safe insertion site of the chest drain
Anterior: Posterior border of the pec major
Posterior: Midaxiallary line
Superior: Apex
Inferior: Line drawn above the 6th rib
Then put a needle in the 5th intercostal space above the 6th rib just anterior to the mid-axillary line.
What is the arterial blood supply of the chest wall
Posterior intercostals: 1 and 2 are supplied by the superior intercostal which is a branch of the costocervical trunk of the subclavian artery. Lower 9 are supplied by branches of the descending thoracic aorta
Anterior: Arises from the internal thoracic (1-6), superior and lateral and thoracic. Muscolophrenic artery supply 7-9.
Subcostal supplies spaces beneath the 12th rib
venous drainage of the thorax
Follows the arteries normally. Anterior is drained into the internal thoracic vein and the BCV and then the SVC. Posterior is azygous venous system.
Define thoracic outlet syndrome
Compression of the subclavian vessels or branches of the brachial plexus as they pass from the thorax into the arm
What are the clinical features of thoracic outlet syndrome
Nervous such as pain, parasthesia, muscle weakness
Arteries: Ischemia UL and emboli
Venous: Swelling UL
What are soem causes of thoracic outlet syndrome
cervical rib, fibrous band, malignancy, trauma
What are the contents of the superior mediastinum
Muscles: Sterno thyroid and sternohyoid
Vessels: Aortic arch, BCV, LCC and LSC, BC and SVC
Nerves: Phrenic, vagus and left recurrent laryngeal
Viscera: Oesophagus and trachea
Others: Thoracic duct, thymus and lymph nodes
What are the contents of the posterior mediastinum
Vessels: Thoracic part od descending aorta and azygous veins
Nerves: Vagus and splanchnic
Viscera: Oesophagus
Others: Lymph nodes and thoracic duct
What are the contents of the middle mediastinum
Vessels: Ascending aorta, lower half of SVC, azygous vein and pulmonary artery and veins
Nerves: Phrenic
Viscera: heart and pericardium
Others: Bronchial lymph nodes
SUbclavian steal syndrome
Patients have the steno-occlusive nature proximal to the origin of the vertebral artery, Hence the retrograde flow.
Can lead to ischemia of thee upper limbs and symptoms of dizziness, vertigo, syncope and other symptoms of potential vertebrobasilar insufficiency.
What type of joint is the manubrium sternii
Secondary cartilagenous joint
What important anatomical structures lie at the manubriosternal joint
SVC entering right atrium
Bif of trachea and pulmonary trunk
Arch of aorta
What are the surface markings of the pleura
It starts at the midclavicular line, then runs along the sternal edge up to the 6th rib, then 8th rib midclav line, then 10th mid ax line and then 12th post ax line
Surface marking of the horizontal fissure
4th intercostal space
Surface marking of oblique fissure
Hands-on head, line drawn from T3 to the lateral sternal border 6th rib along the medial scapular border
What are the signs of cardiac tamponade
Becks triad
Pulsus paradoxus: a fall of more than 10mmHG on insp
Kussmauls sign: Raised JVP on inspiration
progressive tachy and arrhythmia, widened mediastinum on CXR
Name the anatomical landmark of performing a pericardiocentesis
The skin incision should be made just left of the xiphoid process, 1-2cm inferiorly, with needle at 45 degree angle and going towards the left scapula
What are the most common coronary branches that occlude
LAD, RCS and circumflex
How is the SA and AV node supplied
RCA in 60% of people and the LCA in 40%
AV is RCA
Right bundle branch is LCA
Left bundle branch is LCA nad RCA
Describe the anatomy and the function of the pericardium
Thin and double-walled
It has visceral and parietal layers
The visceral is the epicardium and the parietal is attached to the fibrous pericardium
The space is for lubricating fluid
At the base, the fibrous pericardium attaches to the central tendon of the diaphragm
Overall, it helps to anchor the heart in the mediastinum and lubricate as well as prevents excess dilatation
Azygous venous system
What is the thoracic duct
It is the largest lymph channel of the body, it drains most of the body, apart from the right head and neck and arm and the right thorax.
It originates in the cisternal chylie in the abdomen opposite L2
Hemi and accessory hemizygous venous system
WHat structures drain lymph from the right side of the thorax
The right head, neck and thorax is drained by the right lymphatic duct, it joins either the right subclavian or IJV
Management of a chylothorax
Drainage, aspiration
Medical treatment with octreotide to reduce the formation of chyle
TPN to reduce chyle formation. In 50% of patients the leak will self resolve
What is the sympathetic trunk
Ganglionated chain of the ANS arising from the thoracolumbar vertebrae.
What nerves lie on either side of the oesophagus
Rec lar
What is the arterial and venous supply of the oesophagus
Art
Cervical part: Inf thy
Thoracic: Descending TA
abdominal: LGA and inferior phrenic
Venous: Inf thy and azygous, hemi and accessory and left gastric
What is the innervation of the oesophagus
Cervical part: rec lar and sympathetic
Thoracic: oesphagial plexus and symp and greater splanch
Abdo: Lesser splanch, vagal
What is the structure and anatomy of the diaphragm
The diaphragm is a double-domed musculotendinous sheet, located at the inferior-most aspect of the rib cage. It serves two main functions:
Separates the thoracic cavity from the abdominal cavity (the word diaphragm is derived from the Greek ‘diáphragma’, meaning partition).
Undergoes contraction and relaxation, altering the volume of the thoracic cavity and the lungs, producing inspiration and expiration.
It has three peripheral attachments:
Lumbar vertebrae and arcuate ligaments.
Costal cartilages of ribs 7-10 (attach directly to ribs 11-12).
Xiphoid process of the sternum.
The parts of the diaphragm that arise from the vertebrae are tendinous in structure, and are known as the right and left crura:
Right crus – Arises from L1-L3 and their intervertebral discs. Some fibres from the right crus surround the oesophageal opening, acting as a physiological sphincter to prevent reflux of gastric contents into the oesophagus.
Left crus – Arises from L1-L2 and their intervertebral discs.
The muscle fibres of the diaphragm combine to form a central tendon. This tendon ascends to fuse with the inferior surface of the fibrous pericardium. Either side of the pericardium, the diaphragm ascends to form left and right domes. At rest, the right dome lies slightly higher than the left – this is thought to be due to the presence of the liver.
What is the arterial and venous supply of the diaphragm
The majority of the arterial supply to the diaphragm is delivered via the inferior phrenic arteries, which arise directly from the abdominal aorta. The remaining supply is from the superior phrenic, pericardiacophrenic, and musculophrenic arteries. The draining veins follow the aforementioned arteries.
What is the Sibson fascia
Suprapleural extension of the endothoracic fascia, attaches to the inner border of the 1st rib and the transverse process of C7. Prevents further extension of the lungs and pleura into the neck
Subclav artery, vein and brachial plexus lie on it
Stellate ganglion
Formed by fusion of C7 and T1 ganglion
It lies anterior to the transverse process of C7, superior to the neck of the 1st rib, just below the sub clavian artery.
How many bronchopulmonary segments does each lung have
8 left and 10 right
Describe the anatomy of bronchopulmonary segments
Pyramidal shape with apices facing the lung root and the base facing the pleural surface
Supplied by its own tertiary artery and veins.
It is separated from the surrounding lung by connective tissues
veins and lymphatics run along the edge of the segment
Where does the trachea commence
At the level of C6
Where does the lymph from the nipples, areola and glandular tissue of the breast drain into
Subareolar lymphatic plexus and from there it drains into the axillary and parasternal lymph nodes
What is the innervation of the pec major and minor
Pec major is innervated by the medial and lateral pec nerves and pec minor is medial only
What is poland syndrome
Congenital absence or underdevelopment of ipsilateral pec major and webbing of the ipsilateral hand
Describe the surface anatomy of the heart
On the right side, the 3rd and the 6th intercostal space right edge of the sternum
On the left, superiorly 4th intercostal space 2cm left of the sternum and the 5th intercostal space midl clavicular line
What layers does a chest drain pass through
skin
subcutaneous fat
deep fascia
serratus anterior muscle
external intercostal muscle
internal intercostal muscle
innermost intercostal muscle
endothoracic fascia
parietal pleura.
Describe the course of the parietal pleura
The parietal pleura provide the lining of the thoracic cavity. The pleural
cavity extends 3 cm above the first rib anteriorly (but level with the raised posterior aspect of the first rib). The edge of the pleura extends down from the sternoclavicular joint to meet the pleura of the other side at the second rib. At the fourth rib level the left side moves lateral to the sternum, whereas the right side continues down the midline. At the sixth rib both sides turn laterally. At the eighth rib they reach the mid-clavicular line and the mid-axillary line over the tenth rib. The lower border varies according to the position of the diaphragm but lies above the lower border of the rib cage. The pleural line crosses the twelfth rib just lateral to the erector spinae and then passes horizontally to the
T12 vertebra.
Is there any areas where the pleura is not protected by the rib cage
The pleural cavity extends above the upper border of the first rib anteriorly.
Posteriorly the pleural cavity extends below the lower border of the twelfth rib for a short distance on either side of the midline.
Where do different parts of the sternum lie with respect to the vertebrae
- sternal notch - disc between 12 and 13
- manubrium - T3 to T4
- sternal angle (of Louis) - disc between T4 and TS
- body of sternum - T5 to T8
- xiphisternum - T9
What is the arterial supply of the diaphragm
- superior and inferior phrenic arteries from the aorta
- musculophrenic branches of the internal mammary artery
- small contribution from the intercostal arteries to the peripheral parts of the diaphragm
What are the surface markings of the diaphragmatic openings
T8 - xiphisternal junction
T10 - seventh costal cartilage
T12 - just above transpyloric plane.
What are the surface landmarking of the breast
The base of the breast is circular and extends from the lateral border of the sternum to the mid-axillary line, from the second rib down to the sixth rib.
What is the lymph supply of the breast
As a general rule, the lateral part of the breast drains to the axillary lymph nodes, while the medial breast drains to the internal thoracic nodes. There are multiple valveless channels connecting these systems, however, which allow lymph to flow in both directions depending on external pressure and gravity. Most lymph seems to drain into the ipsilateral axillary basin via the anterior axillary nodes and central axillary nodes, through to the apical axillary nodes. Some lymph drains to infraclavicular and supraclavicular nodes, subscapular, interpectoral, rectus sheath, contralateral breast and even mediastinal nodes. Intramammary lymph nodes are frequently found, especially in the upper outer quadrant of the breast.
What is the general anatomy of the breast parenchyma
The female breast is composed of an arrangement of gland and duct tissue, with a variable amount of intervening fat. The terminal duct lobular units produce milk. These drain into approximately 10-20 lactiferous ducts that converge on the nipple in a radial distribution. Each duct has a separate opening in the nipple. The glandular breast is supported by fibrous septae known as the suspensory ligaments of Astley Cooper, which are condensations of fascia that run between the dermis of the breast skin and the posterior capsule of the breast. These ligaments maintain the shape of the young breast but become attenuated with age, leading to ptosis.
Which nerve supplies the nipple
4ht intercostal space
What is the cutaneous supply to the breast skin
The breast skin is supplied by:
* supraclavicular branches of the cervical plexus (C3 and C4)
* lateral cutaneous branches of the anterior thoracic intercostal nerves
*anterior perforating cutaneous branches of the intercostal nerves
* intercostobrachial nerve.
What is the blood supply to the breast
The breast receives blood from four sources:
* medially from branches of the internal mammary artery
* laterally from branches of the lateral thoracic artery
* deeply through perforators from the pectoralis major muscle (thoracoacromial trunk)
* inferiorly/laterally from branches of the intercostal arteries.
What kind of a gland is the breast
Modified apocrine skin gland
Name the following areas of the ribbed
A - head
B - neck
C - tubercle
D - shaft
E - angle
Name the following
A- head
B - neck - The C8 nerve root runs above the neck of the first rib and the T1 nerve root runs below the neck. Both structures then pass above the shaft of the first rib
C- tubercle
D - scalene tubercle.
E - Subclavian vein
F - subclavian artery
G - The T1 nerve root runs in direct contact with the shaft of the rib, with the fibres of the C8 nerve root running above it. These nerve roots merge to form the inferior trunk of the brachial plexus.
H - Middle scalene attaches here
Name the following
A - ascending aorta
B - right pulmonary artery
C - descending aorta
D - body of T5 vertebra
E - superior vena cava
F - right main bronchus
G - left main bronchus
H - oesophagus
I - azygous vein
J- left scapula
K - left lower lobe pulmonary artery
L - left pulmonary vein
M - right pulmonary vein
N - sternum
O - left internal mammary artery.
What structures do you pass through to cannulated the subclavian vein
During subclavian vein cannulation the needle passes through:
* skin
* subcutaneous fat
* deep fascia
* clavicular head of pectoralis major
* clavipectoral fascia
* subclavius
* subclavian vein wall.
At risk of damage are:
* subclavian artery
* phrenic nerve
* apex of lung
* thoracic duct (on left side).
What is the pulmonary ligament
Pleural fold that connects the mediastinal surface of the lung to the pericardium to allow expansion of the pulmonary veins for increased bloodflow
Anatomy of the hilum of the lung
Bronchs will always be Back
Artery can be front or top
vein is mostly at the bottom
How many bronchopulmonary segments are there in each lung
10
Why is there bradycardia after insertion of a chest drain
Irritation of the vagus nerve
What are the contents of the mediastinum
Posterior mediastinum: Esophagus * Thoracic aorta * Azygos vein * Thoracic duct * Vagus nerve * Sympathetic nerve trunks * Splanchnic nerves
Superior: Superior vena cava * Brachiocephalic veins * Arch of aorta * Thoracic duct * Trachea * Esophagus * Thymus * Vagus nerve * Left recurrent laryngeal nerve * Phrenic nerve
Anterior: Thymic remnants * Lymph nodes * Fat
Middle: Pericardium * Heart * Aortic root * Arch of azygos vein * Main bronchi
What is the superior epigastric artery a continuation of
The internal thoracic artery
