Respiratory system anatomy Flashcards
What is the function of the respiratory system?
Ventilation and gas exchange - absorbing oxygen and removing carbon dioxide,
Immunological role - trapping inhaled pathogens. e.g. the tonsils monitor and detect pathogens and bacteria in the inspired air.
What is the upper respiratory tract?
Nasal cavity
Pharynx
Larynx
What is the lower respiratory tract?
Trachea
Bronchi
Lungs
Where are the lungs?
The lungs and trachea are located in the thoracic cavity, surrounded by a bony thoracic wall.
Has functions of protection of the heart and lungs.
Muscles pull on the bones and cause changes in the shape and dimensions of the thoracic cavity, important for breathing.
What are the functions of the bony thoracic cage?
Respiration
Protection
Conduit for passage of other structures in and out of the cavity.
What are the components of the thoracic cage?
The sternum is anterior, down the midline.
Attached are 12 pairs of ribs, that are typical and atypical.
There are also 12 thoracic vertebrae, 1 for each pair of ribs to attach to posteriorly.
What are the regions of the vertebrae?
The vertebrae are the individual bones that make up the vertebral column.
Cervical region
Thoracic region
Lumbar region
What is the superior thoracic aperture of the thoracic cage?
This is the superior (top) opening.
This contains the T1 vertebra, and the 1st rib, and 1st costal cartilage.
It also contains the upper part of the sternum - the manubrium of sternum.
What is the inferior thoracic aperture?
This is where the diaphragm attaches, inferiorly.
This contains the T12 vertebra, the inferior border of rib 12 and the tip of rib 11.
It also has the costal (lower) margin of ribs 7-10.
It contains the lowest part of the sternum - the xiphoid process.
What is the thoracic cavity?
This is the cavity where the organs sit.
The cavity is smaller than the thoracic cage because of the diaphragm.
The diaphragm is a fibromuscular partition which divides the thoracic cavity from the abdominal cavity.
The diaphragm domes upwards superiorly into the thoracic cavity, so it is smaller than the cage.
What is the diaphragm supplied by?
Supplied by the left and right phrenic nerve from C3,C4,C5, which enters through the superior thoracic aperture, to the diaphragm muscle fibres for contraction.
If this is damaged it will impact on breathing.
The diaphragm is also pierced by structures passing through the thoracic cavity to or from the abdominal cavity - arteries, veins and nerves.
What is the diaphragm?
The main muscle of respiration.
It is shaped like a dome, so when it contracts, it pulls the central tendon downwards, and increases the space within the chest wall.
This increase volume creates a negative pressure, so air rushes in to fill this space.
When the diaphragm relaxes, the tendon returns to its position, so volume decreases.
What are the structures passing through the diaphragm?
The inferior vena cava, which will then ascend upwards through the diaphragm to the heart.
The oesophagus.
The thoracic aorta, which then crosses through the diaphragm and becomes the abdominal aorta.
The heart sits on top of the diaphragm, and the pericardium blends with the diaphragm to hold the heart in place.
What are typical ribs?
The head attaches to the vertebrae.
Rib curves round anteriorly towards the costal cartilage which attaches to the sternum.
Costal groove on underside of rib - important as where vessels and nerves pass in.
Ribs 2-11.
What are atypical ribs?
Rib 1 - short and broad, many muscles attach so has grooves.
Rib 12 is short and thin, it has no costal cartilage, and doesn’t curve.
How do the types of ribs differ?
True ribs, have their own individual costal cartilage to attach to the sternum.
False ribs attach to the common cartilage from rib 7, then attach to the sternum.
Floating ribs do not attach to the sternum - no costal cartilage.
What is the movement of the ribs?
The movement of the ribs change the pressure and volume in the thoracic cavity.
When inspiring, the muscles elevate the ribs medially to laterally, and increases the space.
The ribs are also moved posteriorly to anteriorly.
What are the intercostal muscles?
External intercostals - elevates the rib when breathing in.
Internal intercostals - depresses the rib above while breathing out.
Innermost intercostals - depresses the rib while breathing out.
What are the vessels in the intercostal muscles?
Between the upper and lower rib there are vessels - intercostal vein, artery and nerve.
These are found in between the internal intercostal muscle and the innermost intercostal muscle.
How do the intercostal muscles contract during inspiration?
The external intercostal muscle contracts, and pulls the lower rib upwards and laterally.
This increases the space in the thoracic cavity.
How do the intercostal muscles contract during expiration?
The muscle fibres of internal and innermost intercostal muscle are orientated in the opposite direction to the external intercostal muscle.
So when the internal and innermost intercostals contract, they pull the rib above downwards and inwards, bring to original position.
This decreases the space in thoracic cavity.
What are the vessels in the ribs?
The vessels come from the front and back of the rib and join together to form a long continuous vessel that travels in the intercostal spaces.
The costal groove is where the intercostal nerve, vein and arteries travel in and provide additional collateral branches, down to superior border of the rib above it.
As they travel in intercostal spaces, supply blood and innervation to the intercostal muscles.
What are the inspiratory muscles?
Sternocleidomastoid elevate the sternum.
Scalenes elevate the ribs.
External intercostals elevate the ribcage.
The diaphragm.
What are the expiratory muscles?
The internal intercostals depress the ribcage.
The abdominal muscles compresses the abdominal cavity and pushes the diaphragm upward:
The external obliques
The rectus abdominus
Transverse abdominis
Internal obliques.
