Session 1.1h- TeachMeAnatomy - Diaphragm Flashcards
https://teachmeanatomy.info/thorax/muscles/diaphragm/
What is the diaphragm?
A double-domed sheet of skeletal muscle
What type of muscle is the diaphragm?
Skeletal muscle
Where is the diaphragm located?
At the inferior-most aspect of the rib cage.
What are the functions of the diaphragm?
It serves two main functions:
- separates the thoracic cavity from the abdominal cavity (Greek = ‘partition’)
- undergoes contraction and relaxation, altering the volume of the thoracic cavity and the lungs, producing inspiration and expiration.
The diaphragm separates which structures?
The thoracic cavity from the abdominal cavity
What does diaphragm mean?
The word diaphragm is derived from the Greek ‘diáphragma’, meaning partition
The diaphragm undergoes contraction and relaxation to do what?
Alter the volume of the thoracic cavity and the lungs
The diaphragm alters the volume of the thoracic cavity and lungs how?
By undergoing contraction and relaxation
The diaphragm undergoes contraction and relaxation, altering the volume of the thoracic cavity and the lungs, producing what?
Inspiration and expiration
What does the diaphragm fill?
The INFERIOR THORACIC APERTURE
What does the diaphragm act as borders for?
It acts as the floor of the thoracic cavity and the roof the abdominal cavity.
How can the attachments of diaphragm be divided?
Into PERIPHERAL and CENTRAL ATTACHMENTS.
Describe the diaphragm’s peripheral attachments.
It has three:
- 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 ________ in structure
tendinous
The parts of the diaphragm that arise from the vertebrae are known as ___?
The RIGHT AND LEFT CRURA
Where does the right crus arise from?
L1-L3 and their intervertebral discs.
What do some fibres from the right crus surround?
The oesophageal opening
What is the function of the right crus surrounding the oesophageal opening?
It acts as a physiological sphincter to prevent reflux of gastric contents into the oesophagus.
The right crus acts as what sort of muscle when it surrounds the oesophageal opening?
A physiological sphincter
What does the right crus reflux of?
Gastric contents
The right crus prevents reflux of gastric contents where?
Into the oesophagus.
Where does the left crus arise from?
L1-L2 and their intervertebral discs.
The muscle fibres of the diaphragm combine to form what?
A CENTRAL TENDON
The central tendon of the diaphragm ascends to do what?
This tendon ascends to fuse with the inferior surface of the fibrous pericardium.
What happens to the diaphragm at the level of the pericardium?
Either side of the pericardium, the diaphragm ascends to form left and right DOMES.
Which dome of the diaphragm lies higher?
At rest, the right dome lies slightly higher than the left.
Why does one dome of the diaphragm lie higher than the other?
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 significance of the diaphragm dividing the thoracic and abdominal cavities?
Any structures that pass between the two cavities will pierce the diaphragm.
What are the openings in the diaphragm?
There are three openings that act as conduit for various structures:
- Caval Hiatus (T8)
- Oesophageal Hiatus (T10)
- Aortic Hiatus (T12)
At what vertebral level is the caval hiatus?
T8
What opening of the diaphragm is at T8?
Caval hiatus
The caval hiatus is a conduit for which structures?
- Inferior vena cava
- Terminal branches of right phrenic nerve
The inferior vena cava and terminal branches of right phrenic nerve pass through the diaphragm where?
Caval hiatus
At what vertebral level is the oesophageal hiatus?
T10
What opening of the diaphragm is at T10?
Oesophageal hiatus
The oesophageal hiatus is a conduit for which structures?
- Oesophagus
- Right and left vagus nerves
- Oesophageal branches of left gastric artery/vein
The oesophagus, right and left vagus nerves, and oesophageal branches of left gastric artery/veinpass through the diaphragm where?
Oesophageal hiatus
At what vertebral level is the aortic hiatus?
T12
What opening of the diaphragm is at T12?
Aortic hiatus
The aortic hiatus is a conduit for which structures?
- Aorta
- Thoracic duct
- Azygous vein
The aorta, thoracic duct and azygous vein pass through the diaphragm where?
Aortic hiatus
Name a tip for remembering the vertebral levels of the diaphragm.
- Vena cava has eight letters (T8)
- Oesophagus has ten letters (T10)
- Aortic hiatus has twelve letters (T12)
What is the primary muscle of respiration?
The diaphragm is the PRIMARY MUSCLE of respiration.
What does the diaphragm do during inspiration?
It contracts and FLATTENS, increasing the vertical diameter of the thoracic cavity.
The diaphragm contracts and flattens during ___?
Inspiration
The diaphragm contracts and flattens during inspiration to ___?
Increase the vertical diameter of the thoracic cavity.
What is the relation of the diaphragm to the lung in inspiration?
It produces lung expansion, and air is drawn in.
What happens to the diaphragm during expiration?
It passively relaxes and returns to its original dome shape.
The diaphragm relaxes and returns to its original dome shape during expiration. Why?
This reduces the volume of the thoracic cavity.
What is the innervation of the diaphragm?
The halves of the diaphragm receives motor innervation from a PHRENIC NERVE.
The phrenic nerve supplies the _____ innervation of the diaphragm.
Motor
What is half of the diaphragm known as?
A HEMIDIAPHRAGM
What is each half of the diaphragm innervated by?
The left half of the diaphragm is innervated by the left phrenic nerve, and vice versa.
Where is the phrenic nerve formed?
In the neck within the CERVICAL PLEXUS
The phrenic nerve contains fibres from where?
Spinal roots C3-C5.
What delivers the majority of the arterial supply to the diaphragm?
The INFERIOR PHRENIC ARTERIES
Where do the inferior phrenic arteries arise from?
Directly from the abdominal aorta.
Other than the inferior phrenic arteries, what is the remainly supply to the diaphragm?
The superior phrenic, pericardiacophrenic, and musculophrenic arteries.
What are the draining veins of the diaphragm?
The draining veins follow the aforementioned arteries (inferior phrenic, superior phrenic, pericardiacophrenic, musculophrenic).
(Clinical Relevance: Paralysis of the Diaphragm)
What is diaphragmatic paralysis caused by?
An interruption in its nervous supply.
(Clinical Relevance: Paralysis of the Diaphragm)
What structures can be damaged to cause diaphragmatic paralysis?
Interruption in the nervous supply, which can occur in the
- PHRENIC NERVE
- cervical spinal cord
- or the brainstem
(Clinical Relevance: Paralysis of the Diaphragm)
What is the most common cause of diaphragmatic paralysis?
It is most often due to a lesion of the phrenic nerve.
(Clinical Relevance: Paralysis of the Diaphragm)
How can a lesion to the phrenic nerve occur?
- MECHANICAL TRAUMA
- COMPRESSION
- MYOPATHIES
- NEUROPATHIES
(Clinical Relevance: Paralysis of the Diaphragm)
What kind of mechanical trauma can occur to damage the phrenic nerve?
Ligation or damage to the nerve during surgery.
(Clinical Relevance: Paralysis of the Diaphragm)
What sort of compression can occur to damage the phrenic nerve?
Due to a tumour within the chest cavity.
(Clinical Relevance: Paralysis of the Diaphragm)
What myopathies can occur to damage the phrenic nerve?
Such as myasthenia gravis
(Clinical Relevance: Paralysis of the Diaphragm)
What neuropathies can occur to damage the phrenic nerve?
Such diabetic neuropathy
(Clinical Relevance: Paralysis of the Diaphragm)
What does paralysis of the diaphragm do?
Produces a PARADOXICAL MOVEMENT
(Clinical Relevance: Paralysis of the Diaphragm)
What is the paradoxical movement on paralysis of the diaphragm?
The affected side of the diaphragm moves upwards during inspiration, and downwards during expiration.
(Clinical Relevance: Paralysis of the Diaphragm)
How does the diaphragm move during paralysis?
- Upwards during inspiration
- Downwards during expiration
(Clinical Relevance: Paralysis of the Diaphragm)
What occurs in a unilateral diaphragmatic paralysis?
It is usually asymptomatic.
(Clinical Relevance: Paralysis of the Diaphragm)
What sort of diaphragmatic paralysis is asymptomatic?
Unilateral diaphragmatic paralysis
(Clinical Relevance: Paralysis of the Diaphragm)
How is unilateral diaphragmatic paralysis usually diagnosed?
It is most often an incidental finding on x-ray.
(Clinical Relevance: Paralysis of the Diaphragm)
What symptoms will the patience experience if both sides of the diaphragm are paralysed?
The patient may experience
- poor exercise tolerance
- orthopnoea (SOB when lying flat)
- fatigue
(Clinical Relevance: Paralysis of the Diaphragm)
What will lung function tests show?
A RESTRICTIVE DEFICIT
(Clinical Relevance: Paralysis of the Diaphragm)
What is the treatment for diaphragmatic paralysis?
Management is two-fold:
1) underlying cause must be identified and treated
2) symptomatic relief
(Clinical Relevance: Paralysis of the Diaphragm)
What is the first thing you do to treat diaphragmatic paralysis?
Firstly, the underlying cause must be identified and treated.
(Clinical Relevance: Paralysis of the Diaphragm)
What is the second thing you do to treat diaphragmatic paralysis?
The second part of treatment deals with symptomatic relief.
(Clinical Relevance: Paralysis of the Diaphragm)
What sort of symptomatic relief is provided for diaphragmatic paralysis?
This is usually via non-invasive ventilation, such as a CPAP (continuous positive airway pressure) machine.
(Clinical Relevance: Paralysis of the Diaphragm)
Give an example of non-invasive ventilation.
CPAP (continuous positive airway pressure) machine.
(Clinical Relevance: Paralysis of the Diaphragm)
What is a CPAP machine?
CPAP = continuous positive airway pressure
A type of non-invasive ventilation.
Fig. 1
Label and caption the image
- Right Dome
- Left Dome
- Right crus
- Left crus
The diaphragm is split into two lobes, left and right. Note the vertebral attachments of the diaphragm are the left and right crura.
(Note: Right dome at 4th rib, left dome at 5th ICS
Right crus from L1-L3 & intervertebral discs, left crus from L1-L2 & intervertebral discs)
Fig. 2
Label and caption the image
- Sternal attachment
- Central tendon
- Caval hiatus
- Oesophageal hiatus
- Aortic hiatus
- Vertebral attachment
View of the inferior surface of the diaphragm. Note the three openings.
(Caval T8; Oesophageal T10; Aortic T12)
Fig. 3
Label and caption the image
- Pericardium
- Left phrenic nerve
- Right dome of the diaphragm
The anatomical course of the phrenic nerves, which innervate the diaphragm
Fig. 4
Caption the image
Chest x-ray, showing paralysis of the right hemidiaphragm.
Which structure does the central tendon of the diaphragm fuse with?
A. Pericardium
B. Greater omentum
C. Intercostal muscles
D. Ribs 7-12
A. Pericardium
The central tendon fuses with the fibrous pericardium
At what vertebral level is the oesophageal hiatus situated?
A. T8
B. T10
C. T12
D. L2
B. T10
Correct - the oesophageal hiatus is situated at T10.
What is the innervation of the diaphragm?
A. Intercostal nerves
B. Vagus nerves
C. Phrenic nerves
D. Thoracodorsal nerve
C. Phrenic nerves
The right and left phrenic nerves each innervate one half of the diaphragm.