Anatomy of the Thorax 7 Flashcards
What are the three internal compartments of the thoracic cavity?
- Central Mediastinum (and heart)
- Left Pleural cavity (and lung surrounded by 2 layers of simple squamous and the fluid filled pleural cavity)
- Right Pleural cavity (and lung surrounded by 2 layers of simple squamous and the fluid filled pleural cavity)
What is the role of the diaphragm?
Diaphragm movement changes thoracic volume- controls breathing process- inspiration/expiration.
contracts on inhalation/inspiration to enlarge the thoracic cavity - creates a vacuum pulling air down the open airways.
How many lobes are there of the lung?
- 2
- 3
- 4
- 5
- 6
5 lobes
Label
Which articulation can you palpate?
Describe its location.
The jugular notch -a large, visible dip in between the neck in humans → between the clavicles, and above the manubrium of the sternum.
What is the transthoracic plane?
An imaginary horizontal plane used to divide the mediastinum into the superior mediastinum and the inferior mediastinum. Inferior part of the aorta, where trachea bifurcates into two bronchi.
Horizontally travels through the sternal angle and the area between the T4 and T5 thoracic vertebrae.
How many nerves are in the thoracic spine?
What are the main nerves associated with the thorax?
12 thoracic spine nerves. Somatic nervous control-
- Phrenic nerve travels anterior to root of lung-originates from anterior rami of C3, C4 and C5 provides motor and sensory innervation.
- Vagus nerve travels posterior- passes through neck and thorax to the abdomen. It is a cranial nerve carrying parasympathetic supply to organs.
A) What direction do the muscles of the thoracic cage run?
B) What intercostal muscles have fibres that run antero-inferiorly?
- 90 degree like superficial abdominal muscles
- External intercostals
What do the intercostal spaces contain?
- x3 intercostal muscle groups- external, internal and innermost
- Intercostal nerves, arteries, veins (at intercostal groove)
- Pleura
What opening of the diaphragm does the vagus nerve pass through?
Oesophegeal hiatus
What is the pleura made up of? x2 layers
What are each layer of the pleural cavity separated by?
- Inner layer (visceral) that wraps around the lungs and is stuck to them.
- The outer layer (parietal) lines the ribs, diaphragm and mediastinum.
Serous layer -simple squamous epithelium, with serous fluid in between- with a negative pressure.
What is the role of the pleura?
A thin layer of tissue (visceral inner and parietal outer) that covers the lungs and lines the interior walls of the chest cavity. It protects and cushions the lungs.
The tissue secretes a small amount of serous fluid that acts as a lubricant allowing the lungs to move in the chest cavity while breathing.
What are the main differences between the two layers of pleura including innervation, location, role?
Parietal- outer layer- innervated by costal nerves (somatic sensory fibres)-good localisation of pain. Lines the boundaries of the cavity- costal thoracic wall, diaphragm and mediastinum.
Visceral- inner layer- innervated by visceral fibres- poor localisation of pain. Lines the surface of the lung itself
How many lobes does the left and right lung contain?
Right- 3
Left -2
Label
If a patient were to inhale something- where would it end up? Why?
In their right lung - lesser angle of convergence (more vertically relative to the hilum) and the diameter, larger
What are the types of movements the thorax allows for?
Pump Handle: superior and anterior movement of sternum- anterior posterior expansion.
Bucket handle: elevation and lateral - expansion
Define inspiration, what are the primary and secondary muscles involved?
The increase in volume in the the thoracic area by breathing in air.
- Diaphragm- primary
- Scalene muscles- of neck
- sternocleidmastoid
- external intercostals
What are the accessory muscles involved in expiration? For passive recoil of lungs
- Abdominal wall muscles
- Internal intercostals
- Passive recoil of lungs
How many synovial joints does a typical rib (2-9) have with vertebrae?
3.
Whereas ribs 1, 10-12 articulate with just 1.
What happens if the pleura is damaged?
Lungs collapse
Label
What is the hilum of the lungs?
The point of entry on the lungs for bronchi, blood vessels and nerves, (pulmonary arteries-off right ventricle and veins-to left atrium)
**In Embryonic hearts what are the two ways that you can avoid pulmonary circulation
- Foramen ovali allows for blood to move from right atria to left atria- becomes Fossa Ovalis after birth
- Ductus artisosis (connects the aorta and left pulmonary artery) - Becomes the ligamentum arteriosum
What endocrine gland is at the level of the sternal angle?
Thymus - innervated by phenic nerve and internal thoracic arteries
Arteries and nerves that pass anterior and posterior medial plane of the thorax (lungs)*
Phrenic nerve and internal thoracic arteries run anterior
vagus nerve and aorta run posterior
What is happening here?
Myocardial hypertrophy
What is the term for what is shown in this image? And the key structures?
Sternal angle- Angle of Louis- Located at T4, T5 /Rib 2. Found at the articulation between manubrium and body of sternum.
Key structures:
- arch of aorta
- bifurcation of the trachea into bronchia
- emergence of pulmonary trunk
- superior vena cava
- What are the 3 structures that pass through the diaphragm?
- Aorta passes through aortic hiatus (T12)
- Oesophagus passes through oesophageal Hiatus with vagus nerve (T10)
- Inferior vena cava passes through the central tendon (T8)
What are the three origins of the diaphragm?
- Body of T12
- 12 Rib shaft
- Along costal margin until Xiphoid process
**The diaphragm is innervated by the ___, which runs anterior to the heart. Its pericardial branch innervates ____.
The diaphragm is innervated by the phrenic nerve (roots C3, 4,5), which runs anterior to the heart. It pericardial branch innervates the pericardium of the heart.
Where is the vagus nerve in relation to the heart, where does it travel and where does it exit?
Vagus nerve passes posterior to lung root and travel anterior to the aorta, exiting the thorax at T10 oesophageal hiatus (inferior).
Describe the blood supply of the diaphragm
Internal thoracic arteries provide blood to the diaphragm. They are branches of the subclavian artery and run anterior in the mediastinum.
Inferior vena cava returns deoxygenated blood from the diaphragm
Passes diaphragm at T8 via central tendon.
What is located in the inferior intercostal groove?
Intercostal vein, artery and nerve
Describe the effect of Hemothorax of the pleural cavity
Blood cells accumulate in the pleural space. This causes an increase in pressure as it pushes against the lungs resulting in a collapsed lung.
Describe how a collapsed lung occurs
- The lungs naturally want to be deflated but the pleural cavity keeps them inflated.
- The parietal (outside layer) pleura stretch and expands the lungs during inhalation.
- And the pleural space (occupied by serous fluid) has negative pressure, below ATM pressure, that functions as suction to keep the lungs from collapsing.
- If the parietal pleura is punctured, exposing the parietal space and serous fluid between the layers, then the negative pressure is lost.
- This results in a collapsed lung that deflates to the size of a fist.
What is the arrow highlighting?
Carina: the most inferior part of the bronchia - site of bifurcation
The carina usually sits at the level of the sternal angle and the T4/T5 vertebral level in the thoracic plane.
What are the arrows indicating to?
Oblique fissure- separates superior and inferior lobes
What is 11 indicating?
Right coronary artery- thick walled tubular structure
What is the major vein that brings deoxygenated blood from the lower body back to the heart?
Inferior Vena Cava
At what level does the IVC, Aorta and Oesophagus pierce the diaphragm?
T8 (IVC), T12 (Aortic hiatus), T10 (oesophagus hiatus) with vagus nerve
What are the two movements of the lungs?
Inspiration and expiration: They bring oxygen into our bodies (called inspiration, or inhalation) and send carbon dioxide out (called expiration, or exhalation).
- Where do ¾ of lymph drain?
- What is the largest lymph node and its function?
- Right Thoracic duct → subclavian vein → right atria
- Cisterna chyli: collects all lymphatic tissue from lower limbs, drain into left thoracic duct → left subclavian
- What gland is located at the angle of Louis?
- Where does it receive blood from and what is it innervated by?
Thymus
From internal thoracic artery
Phrenic nerve
Why is pulmonary circulation not necessary for embryonic baby?
Because O2 comes from the placenta so bypass is more efficient way to move blood (foramen ovali and ductus arteriosus)
What passes anterior vs posterior to the lung root?
Anterior to lung root= right and left phrenic nerves (C3,4,5)
Posterior to the lung root= right and left vagus (X)
Identify the coronary sinus.
What is the role of the coronary sinus?
Returns all blood from the heart back to the right atria.
What does the right coronary artery seperate?
Right atrium and right ventricle
What are the two branches of the vagus nerve and where do they pass?
pharyngeal branches and superior laryngeal nerves
passes down the neck between the carotid artery and the internal jugular vein
Patient has difficulty swallowing, speaking and loss of gag reflex. You identify they have a damaged vagus nerve.
What is the role of the vagus nerve in relation to the heart?
The vagus nerve carries parasympathetic fibres to the heart. It decreases heart rate through release of acetylcholine
What term is used to describe the remnants of what would have been the 3rd lobe for the left lung?
Lingula
What is one method an embryo heart bypasses pulmonary circulation and what does it turn into?
Ductus arteriosus- a blood vessel that connects aorta and pulmonary artery allowing blood to bypass the lungs. Turns into ligamentus arteriosum.
The aortic arch gives off three branches, what are they?
- Brachiocephalic artery
- Subclavian artery
- Common carotid artery
What are the chambers of the heart?
What is the heart wall comprised of?
- Epicardium (visceral pericardium)= alveolar tissues, simple squamous
- Myocaridum= cardiac muscle tissue, made of cardiac myocytes
- Endocardium = line the heart chambers, simple squamous, attacks to myocardium via alveolar tissue
What are the three structures that deposit blood into the right atria?
- Superior Vena Cava- upper body
- Inferior vena cava- lower body
- Coronary sinus- blood from heart
What is the function and composition of the pericardium?
Protects and attaches heart to the diaphragm.
It is a serous fluid filled sac that covers the heart. Has three parts:
- Parietal (including Fibrous pericardium - attachment to diaphragm): outer layer simple squamous -alveolar tissue and mesothelium
- Pericardial cavity- fluid filled space, pericardial fluid and aids in movement of heart
- Visceral pericardium- inner layer simple squamous, lines the heart tissue directly.
Heart Boarders:
Right =
Base=
Left=
Apex=
Right= right atrium
Base= left and right atria
Left= left ventricle
Apex= left ventricle
What is the difference between the right and left atria?
- Right: collects deoxygenated blood from the body. SVC, IVC, Coronary sinus all deposit blood in the right atria. The tricuspid valve separates the right atria and ventricle and prevents back flow.
- Left: collects oxygenated blood from the 2 pulmonary veins. Separated from left ventricle by bicuspid valve/mitral valve ensures unidirectional flow (atria to ventricle).
What is the most common heart valve to fail? And how does it normally function?
Bicuspid/mitral valve:
Ensures unidirectional blood flow of atria to ventricle. Done by changes in pressure as blood flows between the chambers.
What is the intrinsic conduction system of the heart and describe signal movement.
SA Node→ AV node→ bundle of HIS→Bundle of branches→ purkinje fibres
By pacemaker cells
What are the differences between the right and left ventricles?
- Right= thinner wall because only pumps blood to lungs. Pumps deoxygenated blood into pulmonary arteries. Separated from the aorta via tricuspid valve.
- Left= much thicker wall, pumps blood to entire body. Into the aorta via the aortic valve. Separated from left atria by mitral valve.
What is the role of the papillary muscles and chordae tendinea?
Chordae tendineae = fibrous cords that connect papillary muscles to tricuspid and mitral (bicuspid) valves.
Papillary muscle= pull on the Chordae tendineae and help to open the cusps when the ventricles are relaxing and filling with blood.
When the ventricles contract the pressure makes the valves close . Regulate the closure of the AV valve during systole, limiting back flow
Which artery supplies the SA node?
Right coronary artery-
also supplies: right ventricle, right atrium and AV node.
What is the difference between the atria and ventricles?
Atria=
- Two upper chambers of heart
- Small- consist of thin wall
- Collect blood and supply ventricles in a controlled manner (receptors of deoxygenated blood)
Ventricles=
- Two lower chambers of the heart
- Large- thick wall
- Push blood throughout the body (receive blood from left atria and force it into aorta)
What is the action of the semilunar valve?
OPEN:
- Ventricles contract
- Intraventricular pressure increases
- Pressure from blood forces the valve to open
CLOSED:
- Ventricles relax
- Intraventricular pressure decreases
- Blood flows back, filling valve cusps
- Valves are closed by pressure from blood in valve cusps
Describe the heart valve arrangement and label each valve
- Aortic= anterior to AV valves, posterior to pulmonary
- Pulmonary= most anterior valve
- Tricuspid= AV valve in right atria
- Bicuspid= AV valve in left atria
Describe the cuspid valve action as a step process (open and close)
What causes bicuspid valves to open?
Pressure in atria causes valve to open- blood in ventricles
The pressure in ventricles prior to contraction
Identify the differences in arterial and venous blood supply of the thoracic cavity
Arterial blood: (oxygenated)
- Aorta
- Subclavian
- Common carotid
- Internal thoracic
- Intercostals
Venous: deoxygenated
- Right brachiocephalic
- Superior vena cava
- Inferior vena cava
- Right and left superior intercostal
What creates the:
- Internal thoracic vein?
- Azygous vein?
- Posterior intercostal artery?
- Internal thoracic artery?
- Right brachiocephalic vein
- Superior vena cava
- aorta
- subclavian
When and how do heart valves open and close?
- Firstly, When two atrium chambers contract: tricuspid and mitral valves open which allow blood to move to the ventricles.
- When two ventricle chambers contract: tricuspid and mitral valves close, and pulmonary and aortic valves open. To propel blood out of the heart.
