the volume of the rib cage causes a similar change in the volume of the lungs. As
the volume of the lungs increase, a vacuum is created, causing air to rush in and
ll the lungs. This is called inhalation. As the volume of the lungs decreases, air
within the lungs is pushed out. This is called exhalation.
Expelled air from the lungs passes through the trachea, past the vocal
folds, into the back of the throat and out the mouth or nose. The trachea is a tube
made of exible cartilaginous rings. The boom of the trachea splits into two
branches, one for the left lung and one for the right lung. If inverted, the trachea
forms the trunk of a tree with two main branches: the left and right lungs. The
larynx sits at the top of the trachea. Its primary, biological function is to act as a
valve to keep food and liquids from falling into the lungs. It is the body’s last line
of defense against aspiration.
Muscles and Bones
The lungs are housed inside the ribcage, which protects the lungs and
other vital organs of the upper thorax. The ribcage is formed of twelve pairs of
ribs, all of which originate at the vertebrae of the thoracic (middle and upper)
spine. The top seven pairs of ribs wrap around and connect directly into the
sternum, a at bone in the front of the chest commonly called the breastbone.
These seven ribs have very lile exibility and move very lile in the breathing
process. Ribs 8, 9, and 10 also aach to the sternum but in a more indirect