Week 1 Flashcards
Thoracic cage is comprised of?
- 12 thoracic vertebrae
- 12 pairs of ribs
- Sternum
Function of thoracic cage
House and protect the internal organs
Thoracic cavity is limited superiorly by?
First ribs (surrounding the thoracic inlet)
Thoracic cavity is limited inferiorly by?
Muscular diaphragm (closing off the thoracic outlet)
Domes of the diaphragm lie at approximately the?
5th intercostal space during expiration
Between the ribs, the intercostal space is bridged by?
External, internal and innermost intercostal muscles
Between internal and innermost intercostal muscle layers resides a neurovascular bundle consisting of?
- Intercostal vein
- Intercostal artery
- Intercostal nerve
Intercostal vein drains into?
Azygous and hemi-azygous venous systems
Intercostal artery is supplied by the?
Aorta
Intercostal nerve branches off the _____ and passes through the _______.
Thoracic spinal cord segments; sympathetic trunk
Principle muscle of respiration
Diaphragm
Diaphragm is innervated by?
2 phrenic nerves (left and right)
2 phrenic nerves originates from?
Cervical spinal cord segments C3-5
Pneumonic for C3-5
C3-4-5 keeps the diaphragm alive
What happens to diaphragm during quiet inspiration?
Diaphragm descends to increase the thoracic volume and produce a corresponding decrease in intrathoracic pressure
Decrease in intrathoracic pressure promotes?
Promotes passage of air into the lungs
During passive expiration, what happens to diaphragm?
Diaphragm recoils to decrease the thoracic volume producing a corresponding increase in intrathoracic pressure causing air expulsion.
Contraction of the intercostal muscles causes?
Increases intrathoracic volume by elevating and separating the ribs
During periods of increased oxygen requirement (e.g. exercise, airway obstruction), which muscles become active?
Accessory muscles of inspiration activate and elevate the ribs to further increase intrathoracic volume.
Accessory muscles of inspiration include
- Pectoralis minor
- Scalenes
- Sternocleidomastoid
- Intercostal muscles
During forced expiration (e.g. blowing up a balloon, playing a trumpet), which muscles activate?
Contraction of abdominal muscles increases intrathoracic pressure facilitating air exit from the lungs
Air passes to the lungs from the upper respiratory system via the?
Trachea
Trachea begins at ?
At the inferior border of the larynx (CV6)
Trachea is kept patent (held open) by?
16-20 C-shaped rings of hyaline cartilage that are open posteriorly and completed by the trachealis muscle (smooth).