The Thorax Flashcards
State the functions of the thoracic cage
- Protection: Bony cage around the vital organs
2. Respiratory movements: changes in thoracic volume underlie movement of fresh air into lungs and stake air out
The thoracic cage is formed posteriorly by what part of the vertebral column?
The 12 thoracic vertebrae part of the vertebral column
The thoracic cage is formed anteriorly by what?
The stern and costal cartilages
How many processes make up the sternum and what are they called?
3 processes make up the sternum:
- The manubrium
- The body
- The Xiphoid process
What is the sternal angle?
The line separating the manubrium and body in the sternum
Why is the sternal angle an important clinical feature?
The sternal angle is an important bony landmark at the T4 or 5 vertebral level.
It indicates the manubriosternal junction and the level of the second costal cartilages
It is a reference point in counting ribs.
If you were to cut horizontally from the sternal angle you would find the:
T4 or 5 vertebral
2nd rib articulates here
The aortic arch
Azygous vein
Left recurrent laryngeal nerve
Bifurcation of the pulmonary trunk
Bifurcation of the trachea
What 2 categories can the ribs be split into?
Typical ribs
Atypical ribs
What is the 5th rib articulated to?
The vertebral column posteriorly
Sternum column anteriorly
What are the 2 functions of the costa cartilage?
- extend the ribs into forward motion
- the cartilage also contributes to elasticity within the walls of the thorax allowing the chest to expand during respiration
Which is the lowest rib that forms part of the costal margin?
The 7th rib
Which ribs fall under the typical category?
Ribs 3-9
What makes a rib “typical” ?
Typical ribs are ribs with typical (similar) features
The typical rib consists of a head, neck and body
Describe the head of a typical ribs
The head is wedge shaped and has two articular facets separated by a wedge of bone. One facet articulates with the numerically corresponding vertebrae, and the other articulates with the vertebrae above.
Describe the neck of a typical ribs
The neck of a typical rib contains no bony prominences, but simply connects the head with the body. Where the neck meets the body there is a roughed tubercle, with a facet for articulation with the transverse process of the corresponding vertebrae.
Describe the body of a typical ribs
The body, or shaft of the rib is flat and curved. The internal surface of the shaft has a groove for the neurovascular supply of the thorax, protecting the vessels and nerves from damage
Which ribs fall under the atypical category?
Ribs 1, 2, 10, 11 and 12
What makes rib 1 atypical
Rib 1 is shorter and wider than the other ribs.
It only has one facet on its head for articulation with its corresponding vertebrae (there isn’t a thoracic vertebrae above it).
The superior surface is marked by two grooves, which make way for the subclavian vessels.
What makes rib 2 atypical
Rib 2 is thinner and longer than rib 1,
Has two articular facets on the head as normal.
It has a roughened area on its upper surface, where the serratus anterior muscle attaches.
What makes rib 10 atypical
Rib 10 only has one facet – for articulation with its numerically corresponding vertebrae
What makes rib 11 and 12 atypical
Ribs 11 and 12 have no neck, and only contain one facet, which is for articulation with their corresponding vertebrae
How do structures pass through the diaphragm?
They pass through a number of apertures associated with the diaphragm.
Why do structures need to pass through the diaphragm
In order to pass between the thoracic and abdominal cavities
Which structures pass through the aortic opening?
Aorta
Thoracic duct Azygos vein
Which structures pass through the oesophageal opening?
Oesophagus
Vagus nerves,
Oesophageal branches of the gastric vessels
Lymphatics
Which structures pass through the vena caval opening?
Inferior vena cava
Right phrenic nerve
Which structures pass through the diaphragm?
Sympathetic trunk Left phrenic nerve Superior epigastric artery Aorta Thoracic duct Azygos vein Oesophagus Vagus nerves Oesophageal branches of the gastric vessels Lymphatics Inferior vena cava Right phrenic nerve
Which nerve innervates the diaphragm and from which spinal roots does this nerve originate?
Innervated from a phrenic nerve
Each phrenic nerve is formed in the neck within the cervical plexus and contains spinal roots C3-C5
What can the thoracic cavity be divided into?
The thoracic cavity can be divided into the left and right pleural cavities on both sides of the mediastinum
What are the 2 layers that make up the pleura?
- Visceral Layer
2. Parietal Layer
What does the Visceral Layer cover?
It lines the lungs
What does the Parietal Layer cover?
It lines the rib cage, diaphragm, and mediastinal structures.
What lies between the lungs?
The mediastinum
What is the mediastinum divided into?
The the superior mediastinum
The inferior mediastinum
What separates the superior mediastinum from the inferior mediastinum?
A horizontal plane passing through the sternal angle and the lower border of the 4th thoracic vertebra
What is the inferior mediastinum divided into?
- The anterior mediastinum
- The middle mediastinum
- The posterior mediastinum.
What is the mediastinum covered by?
By the mediastinal parietal pleura.
Where is the only place the mediastinum isn’t lined by mediastinal parietal pleura?
At the lung roots, where structures pass between the mediastinum and the lungs
What are the contents of the superior mediastinum?
The great vessels (the aorta, pulmonary trunk and the superior vena cava) Thymus Trachea Oesophagus Vagus nerves Phrenic nerves Left recurrent laryngeal branch of the vagus nerve Thoracic duct
What is the function of the thymus in children?
The thymus is an important part of your child’s lymphatic system.
Tthe thymus is instrumental in the production and maturation of T-lymphocytes (T cells)
The thymus produces and secretes thymosin, a hormone necessary for T cell development and production.
How does the structure of the thymus change with advancing age?
It is at its largest in children.
Once you reach puberty, the thymus starts to slowly shrink and become replaced by fat and by adipose tissue
Where is the anterior mediastinum found?
The anterior mediastinum is the area between the posterior aspect of the sternal body and the anterior aspect of the pericardium
What does the anterior mediastinum contain?
It contains the ligaments binding the fibrous pericardium to the posterior aspect of the sternum with one or two lymph nodes and small vessels.
What borders the anterior mediastinum laterally?
The mediastinal pleura
What borders the anterior mediastinum inferiorly?
The diaphragm
What does the middle mediastinum compromise of?
the pericardium the heart Also includes: the pulmonary trunk the two bronchi the ascending aorta the terminal part of the superior vena cava
What borders the posterior mediastinum anteriorly?
The posterior aspect of the fibrous pericardium
What borders the posterior mediastinum posteriorly?
The anterior surface of the thoracic vertebral bodies T4- T12.
What borders the posterior mediastinum laterally?
It is bounded by mediastinal parietal pleura
What are the principal contents of the posterior mediastinum?
Thoracic aorta and its branches Oesophagus Thoracic duct Azygos and Hemiazygos veins Lymph nodes Thoracic splanchnic nerves Sympathetic trunks
What is the function of the oesophagus?
The esophagus is a tube that connects the throat and the stomach.
It allows food and drink to travel along it to make it to the stomach
What is the function of the descending aorta?
It supplies blood to the esophagus, lungs, and the chest area, including the ribs and mammary glands
What are the 6 branches of the decending aorta?
- bronchial arteries (found in the thorax)
- mediastinal arteries (found in the thorax)
- oesophageal arteries
- pericardial arteries
- superior phrenic artery
- intercostal arteries. (found in the thorax)
Which 3 branches of the descending aorta are found in the thorax?
- The bronchial arteries
- The mediastinal arteries
- The intercostal arteries
From where does the azygous vein enter the thorax from?
Through the aortic opening
What does the azygous vein pass through?
It passes superiorly (anterior to the thoracic vertebral bodies) to reach the level of the 4th thoracic vertebra where it arches anteriorly (superior to the root of the right lung) to drain into the superior vena cava.
Where does the azygous vein drain into?
The superior vena cava
What is the function of the azygous vein?
The azygos vein transports deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava vein.
It drains venous blood from the thoracic wall and upper lumbar region.
It creates an essential collateral channel attaching the superior vena cava and inferior vena cava
What is found between the aorta and the azygous vein?
The thoracic duct
What is the function of the thoracic duct?
A large portion of the body’s lymph is collected by this duct and then drained into the bloodstream near the brachiocephalic vein between the internal jugular and the left subclavian veins.
What is the thoracic duct?
The thoracic duct is the largest lymphatic vessel within the human body, and plays a key role in the lymphatic system
Is the mediastinum a ridge structure?
NO
What is mediastinal shift?
Movement of the mediastinum within the thoracic cavity
The mediastinum may shift from its central position to either the right or left of the thoracic cavity
What does the pericardium surround?
The pericardium surrounds the heart
What is the pericardium made up of?
Consists of a fibrous (outer) layer Two serous (inner) layers.
Describe the fibrous pericardium
The fibrous pericardium is a tough sac enclosing the heart and the serous pericardium,
It attaches the heart to adjacent structures
Describe the serous pericardium
The serous pericardium has two layers, between which is the pericardial cavity, with a small amount of pericardial fluid
What does the pericardial cavity aid?
It facilitates the movement associated with the beating of the heart.
Under normal conditions it provides lubrication during heart beating
Where does the pericardial fluid come from?
It is the serous fluid secreted by the serous layer of the pericardium into the pericardialcavity.
The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly.
What does the visceral serous pericardium form?
Forms part of the heart wall
What is the visceral serous pericardium known as?
The epicardium
Where does serous pericardium extend around?
Serous pericardium extends around the aorta and the pulmonary trunk (similar to sleeves) as they pass through the fibrous pericardium.
What does serous pericardium surround?
Serous pericardium surrounds the superior and inferior venae cavae, and the four pulmonary veins near their terminations.
Which arteries supply blood to the heart?
The left and right coronary arteries supply arterial blood to the heart.
Why are the right and left coronary arteries important?
They supply the heart muscle (myocardium) with oxygen and glucose so that the heart can pump effectively.
What can happen if one or both of the carotid arteries is blocked?
If one or both of the coronary arteries becomes blocked, and blood flow is severely reduced or stops, the myocardium supplied by that vessel (or branch) is starved of oxygen and the cardiac cells may start to die.
This is what happens during a heart attack (myocardial infarction).
What is the consequence of a blockage in the anterior interventricular (left anterior descending) artery?
Blockage of this artery due to can lead to impairment or death (infarction) of the conducting system.
The result is a “block” of impulse conduction between the atria and the ventricles known as “right/left bundle branch block.”
What is 2/3 of the venous drainage done by?
Via the cardiac veins which accompany the coronary arteries and drain into the right atrium via the coronary sinus
Where do the anterior cardiac veins open into?
Directly into the right atrium
What is the ridge that separates the rough and smooth portion (in the right atrium) called?
The crista terminalis
What is the right atrium composed off
Rough and smooth portion separated by the crista terminalis
Describe the rough section of the right atrium
It is smaller
It corresponds to the auricular appendage, with elevations known as pectinate muscles
What are elevations in the rough portion of the right atrium called?
Pectinate muscles
Describe the smooth section of the right atrium
The smooth walled portion receives the openings of the superior and inferior venae cavae and the coronary sinus.
What is the smooth walled portion of the right atrium called?
sinus venarum
What is the Fossa Ovalis?
It is a sooth depression in the right atrium
It is a remnant of the foetal structure the Foramen Ovale
What is the purpose of the foramen ovale in the foetus?
It allows for the movement of highly oxygenated blood from right atrium to left atrium
Name the 3 shunts important in foetal circulation?
The ductus arteriosus
Ductus venosus
What does the Ductus venosus do?
Carries mostly highly oxygenated blood
What does The ductus arteriosus do?
Protects lungs against circulatory overload
Allows the right ventricle to strengthen
Has a high pulmonary vascular resistance,
Has a low pulmonary blood flow
Carries mostly medium oxygen saturated blood
What is the moderator band?
A prominent ridge passing from the interventricular septum to the anterior wall of the right ventricle
What is the right atrioventricular valve also called?
The tricuspid valves
What are the atrioventricular valves attached to?
The atrioventricular valve are attached to the ventricular wall by tendinous cords (chordae tendineae)
What are the tendons cords also called
chordae tendineae
What are the tendons cords attached to?
The enlarged trabeculae carneae
What are the papillary muscles?
Extensions of the trabeculae carneae which project out into the ventricular lumen
What places tension on the cords in the heart?
The papillary muscles
What is the outlet for the right ventricle?
The pulmonary trunk which is guarded by three semilunar cusps which constitute the pulmonary valve
What is the function of the moderator band?
To act as a primary conduction path into the free wall originating from the right bundle branch
What is the function of the tendinous cords and papillary muscles?
They prevent prolapsing of the valves into the atria during ventricular contraction
Describe the left atrium
It is thin walled and has a smooth and a roughened portion
Describe the rough portion of the left atrium
The roughened portion corresponds to the auricular appendage
What makes up the smooth part of the left atrium?
The smooth walled portion is formed by the incorporation of the 4 pulmonary veins during development.
What is the valve more comminly knows as?
The mitral valve
What do both the left and right lung have in common?
Each lung has: A blunt apex Concave diaphragmatic and mediastinal surfaces A convex costal surface An oblique fissure
What does the oblique fissure do in the lungs?
Separates the upper and lower lobes.
What structure is exclusive to the right lung?
a transverse (horizontal) fissure which, with the oblique fissure separates the middle lobe
What is the right lung split into?
3 lobes:
- The superior lobe
- The middle lobe
- The inferior lobe
What is the left lung split into?
2 lobes:
- The superior lobe
- The inferior lobe
What is the hilum of the lung?
The region on the medial surface of the lung where blood vessels enter and exit the lung, and where the main bronchus enters the lung
Where do the visceral and parietal pleura meet in the lungs?
The pulmonary ligament
Where is the pulmonary ligament found?
At the inferior aspect of the hilum
What is the root of the lung?
The root of lung is a short broad pedicle connecting the medial surface of the lung with the mediastinum.
It consists of structures entering and leaving the lung at hilum.
The root of lung is surrounded by a tubular sheath derived from the mediastinal pleura.
Why do impressions and grooves of anatomical structures that lie right beside the lungs appear on the lungs?
because the lungs are very soft
Describe he trachea and where is passes through?
The trachea descends as a single tube through the superior mediastinum before dividing into the left and right primary bronchi at the level of T4.
What is the bifurcation point where the trachea splits into the left and right branches called?
The carina.
What happens to the primary bronchi and what does it pass through?
Each of the primary bronchi passes into the hilum of the left and right lung respectively before dividing further within the lung tissue into secondary bronchi and bronchioles.
What do the left and right coronary arteries supply?
The arterial blood to the heart.
Where does the mediasternum lie?
Between the lungs
Through which opening does the vagus nerve pass through? (Give the corresponding T level they pass through)
Oesophageal opening
At T10
What is the carina?
The bifurcation point where the trachea splits into the left and right branches
Through which opening does the oesophageal branches of the gastric vessels and lympahatics nerve pass through?
Oesophageal opening
At T10
What lines the lungs?
The visceral pleura
Through which opening does the inferior vena cava nerve pass through? (Give the corresponding T level they pass through)
Vena caval opening
At T8
What is the movement of the mediastinum from its central position in the thoracic cavity called?
mediastinal shift
Through which opening does the right phrenic nerve pass through? (Give the corresponding T level they pass through)
Vena caval opening
At T8
Which ribs only has 1 faucet and what is it for?
Rib 10, 11 and 12
Their faucet is used for articulation with their corresponding vertebrae
Which of the 12 ribs is the shortest?
The first rib
Which 2 ribs have no head or neck?
Ribs 11 and 12
Through which opening does the aorta pass though? (Give the corresponding T level they pass through)
Through which opening does the aorta pass though? (Give the corresponding T level they pass through)
Where do cardiac veins empty into?
They drain into the right atrium via the coronary sinus.
The phrenic nerve innervates which structure in the thorax?
The diaphragm
Through which opening does the thoracic duct nerve pass through? (Give the corresponding T level they pass through)
Aortic opening
At T12
What is a remnant of the foetal structure the Foramen Ovale in the right atrium?
A smooth depression called the Fossa Ovalis
Through which opening does the azygous vein nerve pass through? (Give the corresponding T level they pass through)
Aortic opening
At T12
What lines the rib cage, diaphragm, and mediastinal structures.?
The parietal pleura
What is the smooth depression in the right atrium called?
The Fossa ovalis
Through which opening does the oesophagus nerve pass through? (Give the corresponding T level they pass through)
Oesophageal opening
At T10
